Hurricanes, High-rises, and Hubris

There's been a lot of focus on the potential effects of hurricane winds on high-rises recently. Herbert Saffir was a guest blogger last week on Roger Pielke Sr's Climate Science blog, talking about damage to high-rise buildings in NOLA from Hurricane Katrina. When Max Mayfield left the NHC last month, he gave an interview in the LA Times describing what they referred to as an "apocalyptic vision" and in which he also was critical of lenient building codes in coastal cities, specifically referring to high-rises. Also continually in the news this past year is the transformation of portions of the MS Gulf Coast into another "Miami Beach" of high-rise high-price condos, if real estate developers get their way.

In NOLA, Cat 1 winds / gusts caused inner walls to fail in a hotel room after the windows were broken from flying debris. Seeing this, I researched high-rise damage from Cat 4 Wilma, which made a direct hit on the many high-rise hotels of Cancun's exposed peninsula. The Mexican government downplayed the damage because of the tourist trade, but it took about a year for the resorts to rebuild. Much of the interior damage was caused by window breakage from flying debris, or failure of the framing to keep water from coming in.

Into this current climate, last week I reviewed a video on You Tube of footage taken in a high-rise during 1989's Hurricane Hugo. The video claims to have captured Cat 4 windspeeds.

My first thought on viewing the video was that the top windspeeds appeared to be around 100-110 mph (about equivalent to 90-95 kt) -- a strong Cat 2, based on the size of flying debris that was seen, and the condition of the palms after the high winds had passed (the majority were not denuded). I also observed the winds were mainly being filmed as they funneled between two high-rises (Bernoulli effect).

Then I read the commentary that went along with the video.

My second thought was that someone who lives in a coastal high-rise in an area vulnerable to hurricanes was going to watch this video, read the information provided about the video, and conclude that not only would it not be necessary to evacuate any major hurricane (Cat 3-4-5) bearing down on them, since the high-rise in the video remained intact during "Cat 4" winds, but that it might be a fine and dandy thing to sit and watch it right out their window.

In an objective look at the details, I've reprinted the commentary that went with the video, and highlighted statements that could be compared with known observations, along with those observations, below:

This is my Hurricane Hugo chase video. The footage was taken during Hugo's landfall on the northeast tip of Puerto Rico at Luquillo. In my 25 years of hurricane chasing, this remains, overall, the best footage I have ever been fortunate enough to capture. Though I have been in stronger hurricanes, given that Hugo was a Category Four and the strongest portion of the eyewall passed directly over my location (during daylight hours), I had the rare opportunity to document the full force of an intense hurricane at a direct coastal location. Though significant damage begins about 8 minutes into the video, the peak winds occur between 10 through 21 minutes in, and are sustained near 135mph with gusts to 160-170mph. An anemometer on the island of Culebra (just offshore Eastern Puerto Rico) reported a peak gust of 170mph when the same portion of the eyewall passed over that location a couple of hours prior to reaching Luquillo.​


"Hugo was a Category Four"

The best track and the NHC report on Hugo state the maximum intensitiy to be 110 kt (127 mph) -- a Cat 3 -- not a Cat 4 -- at the time Hugo hit the island of Vieques, and again shortly afterwards when it hit mainland Puerto Rico.


"the strongest portion of the eyewall passed directly over my location [at Luquillo]"

Hugo was travelling northwest, and made landfall just on the very northeast corner of Puerto Rico as it passed.

The lat and lon of the best track shows the center of Hugo moved past to the northeast of Luquillo, so Luquillo was hit with the northwestern eyewall.

This can also be seen in the video, where the northeast-facing beachfront is subject to onshore winds coming from the northeast, which also places it to the west of the center of the storm (cyclonic winds move counter-clockwise in the northern hemisphere, so that in the northwest portion of the eyewall, winds are coming from the northeast).

The strongest winds of the hurricane were likely located in the typically-more-powerful portion of the hurricane to the right of the forward movement, not in the portion of the eyewall that passed over Luquillo. At the time Hugo was moving northwest, so the strongest winds would likely have been to the north and east of the center -- offshore and well to the east of Puerto Rico.


"the peak winds...are sustained near 135mph with gusts to 160-170mph"

As already mentioned Hugo was not a Cat 4 at landfall in Puerto Rico, but a Cat 3. Peak windspeeds were determined to be 127 mph (110 kt), but likely remained offshore. The highest sustained winds measured on land in Puerto Rico were Cat 2.


"a peak gust of 170 mph when...the same portion of the eyewall passed over that location a couple of hours prior to reaching Luquillo"

This gust of 148 kt (170 mph) on the island of Culebra was actually a significant distance away: about 25 miles due east of Luquillo, and to the east of the eye. The portion of the storm that passed over Culebra would have continued on the northwest track, and so by the time it was as far west as Luquillo, would have been far away, around 25 miles to the north of Luquillo. And the NHC report does not state the time the gust occurred. The fact that the highest recorded gust occured to the east of the eye supports the premise that the strongest winds were associated, as usual, with the northeast quad of the storm, and remained offshore of Puerto Rico.

However the northwestern eyewall that passed over Luquillo, did pass over another area of Puerto Rico prior to crossing Luquillo, with documented windspeeds. This was a US Naval Air Station to the southeast of Luquillo. The official readings were labeled "Roosevelt Roads." The maximum sustained windspeed there was 104 mph (90 kt), with a gust to 120 mph (104 kt) -- solid Cat 2 winds. This was the highest sustained windspeed noted over land in Puerto Rico.

Also of note is that the minimum pressure at Roosevelt Roads was 946.1 mbar, and occured at 1250Z. The minimum pressure at Luquillo was 956 mbar, noticeably higher, and that occured ten minutes later at 1300Z.

For those who find these things as facinating as I do, and are interested in taking a closer look, I provide the link to the NHC Hugo report, the recon obs, and the relevant best track points below, which can be plugged into Google Maps -- which also provides a quick and easy way to look at the various locations that were mentioned.

18/0600Z 17.7N 64.8W 940 mbar 110 kt <-- this was a typo, as noted in subsequent post; should read 120 kt
18/1200Z 18.2N 65.5W 945 mbar 110 kt
18/1800Z 19.1N 66.4W 958 mbar 105 kt
19/0000Z 19.7N 66.8W 959 mbar 100 kt

Luquillo is located at 18.375N 65.715W. Landfall on the Puerto Rican mainland was identified in the NHC report as being at Fajardo, at 18/1300Z, with a pressure of 946 mbar.
 
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the most relevant data, the advisory just before landfall was quoted incorrectly. She states the winds were 110 knts., when the advisory preceding landfall was actually: 32 17.70 -64.80 09/18/06Z 120 knts. 940 HURRICANE-4. ( advisory 32; lat 17.7, long 64.8, 09/18/06 z, max winds 120 knots, cat 4). . She must have gotten the winds off a misprinted table that said 110 knts.).

I never referred to an advisory. The post analysis contains the relevant data, including the best track and intensities at landfall. I provided that link in my original post, and even went to the trouble of typing the specifics of the best track points for that portion of the track (I also recommend reviewing the best track max sustained wind graph which is plotted against the observed data).

From the very first page of the NHC report on Hugo:

When the eye passed over the island of Vieques, Puerto Rico, it is estimated that the maximum one-minute wind speed had decreased to 110 knots...Maximum wind speeds were also estimated at 110 knots one hour later when the eye passed over the eastern tip of Puerto Rico. However, the highest recorded wind speed over land was 90 knots with a gust to 104 knots at Roosevelt Roads.​

although Roosevelt Roads is "on" the coast...the wind speeds recorded there are not representave.

NHC takes great care with accuracy. Wind speeds that are not considered representative are not included in the post analysis.


To give a current-day analogy, for similar windspeeds, Katrina's Public Advisories just prior to landfall were still indicating a Cat 4 hurricane, even though real-time analysis showed weakening. NHC will never downgrade on an advisory just prior to a landfall in this type of situation, to my knowledge. However, in the post-analysis, Kat was downgraded to a Cat 3 for both the LA and the MS landfalls (even though there were only Cat 2 winds recorded in MS). Prior to the relase of the Tropical Cyclone Report there was some speculation among mets that I talked with that the MS landfall would be downgraded to a Cat 2. The TC report also contains the best track information.

The TC reports can be updated after the initial release. For instance, the Katrina report was updated a year later, in 2006: "Updated 10 August 2006 for tropical wave history, storm surge, tornadoes, surface observations, fatalities, and damage cost estimates." And the NHC best track data for 2006 was recently updated both in January and, for four storms, again, in February. Also, reanalyses can be done years later, such as with Andrew.

But once the post-season storm analysis is complete, and the TC report containing the best track data is released, that supercedes the advisory information. And analyses can go in both directions; 2005's Cindy was upgraded to a hurricane based on the post-season analysis.
 
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Below is the exact wording from the last public advisory on Katrina BEFORE it made landfall along the Mississippi coast...

It wasn't; the MS landfall was officially at 9:45am (i.e, the downgrade could have had something to do with the fact that the hurricane had just made landfall). But regardless of why the downgrade was made, this cannot be considered an advisory that was issued prior to landfall.


The downgrading was based on the recon. reports minutes before that advisory was issued...

The NHC report paints a different picture:

The strongest surface (10 m) wind measured by dropwindsonde on the morning of 29 August was 99 kt from two separate sondes. The maximum surface wind estimate from a dropwindsonde, derived from the mean wind over the lowest 150 m of the sounding using an average adjustment derived from profiles in several storms, was 98 kt.

…all available data from aircraft indicate that Katrina’s winds weakened only slightly between the first and last Gulf coast landfalls. Just prior to final landfall, surface (10 m) winds measured by dropwindsonde were as strong as 99 kt, adjustment to the surface of the mean wind speed in the lowest 150 m of dropwindsonde profiles yielded surface winds of 90-95 kt, and SFMR winds were as strong as 91 kt. [emphasis mine]


...the central pressure was still 927 mb, which is usually representative of a STRONG cat #4 storm.

Actually...and this just came up recently in another conversation -- the wind-pressure relationship is not constant and does change with respect to whether a storm is strengthening or weakening. The best track is too coarse a measure to tell very many interesting things about intensity; however it does show very clearly the different range of values in the wind-pressure data distribution for strengthening vs. weakening storms. So in this case that same 10am advisory had a max of 125 mph, Cat 3 winds, for the pressure of 927 mbar. The closest best track point to this one, three hours earlier, had an mslp of 923 mbar and the same windspeed (110 kt).

Here is an example from the AL basin for the most recent years of data, for the range including the mslp of 927. Note that 130-135 kt is almost a dividing line for this particular range of mslp (90% of weakening TC are 130 kt or less, and 90% of strengthening TC are 135 kt or higher).

Range of vmax for mslp of 920-929, strengthening:

vmax frequency
---- ---------
120 1
125 1
130 1
135 6
140 6
145 6

Range of vmax for mslp of 920-929, weakening:

vmax frequency
---- ---------
105 1
110 3
115 4
120 3
125 7
130 9
135 1
140 1
145 1
 
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Hubris indeed!

Hi Margie - Thanks for your candor and perspective on my Hugo video and comments. I certainly welcome all personal opinions, and you definitely seem to have some aptitude in the field of tropical meteorology.

That said, I'd like to clarify a few things, from my first-hand perspective, and pose a few questions to your "claims" as well.

My first thought on viewing the video was that the top windspeeds appeared to be around 100-110 mph (about equivalent to 90-95 kt) -- a strong Cat 2, based on the size of flying debris that was seen, and the condition of the palms after the high winds had passed (the majority were not denuded). I also observed the winds were mainly being filmed as they funneled between two high-rises (Bernoulli effect).

My first thought, on reading your comment above, was that if you truly believe the peak winds in my Hugo video to be that of a strong Category Two, then you clearly have a bit still to learn about the characterictics and dynamics of tropical cyclone winds and their impacts.

To your specific comments, I'm not sure what "flying debris" you're using as your reference point(s) to determine the "peak" winds, but the majority of debris, that is actually "visible" in my video, occurs prior to the arrival of the eyewall. During the peak of the storm it is difficult to see much of anything that is going on beyond a couple hundred yards, and the only "visible" debris are windows being ripped out of the neighboring building followed occasionally by people's furniture falling out. At the time of the eye passage, we noted numerous instances of significant structural damage, both in the condo that we were in, as well as in the town of Luquillo. As examples:

hugo_011.jpeg

Numerous leeward facing windows, even in the center of the building on lower levels, were ripped (inclusive of their frames) out of the concrete, after interior walls failed. I certainly don't think this implies to anyone that it would "not be necessary to evacuate any major hurricane (Cat 3-4-5)" or that "it might be fine and dandy to sit and watch...right out their window."

hugo_012.jpeg

The second floor of this home was completely intact prior to our chase team going into the stairwell in the video. So sometime between that point and the arrival of the eye this home was destroyed. The peak winds during the eyewall probably occurred while we were in the stairwell, as evidenced by the incredibly high-pitched wailing attending the one gust that you can hear at 0:17:15, easily the strongest gust I recall during the entire event.

hugo_014.jpeg

As a separate point of reference, although dramatic looking, this flimsy wood-frame constructed home did completely fall apart in winds of 90-95kts. That said, this happened long before the arrival of the eyewall.

As Richard pointed out in his response, our five team members comprised some of, if not, the most experienced hurricane chasers at that time. Prior to Hugo, I already had numerous field interceptions including Hurricanes Elena, Gloria, Kate, Bonnie and Gilbert ...not to mention my colleagues who, by that time, had nearly 30 years of experience, each! Certainly enough familiarity with tropical cyclones of all intensities that we would know the difference between 90-95kts and 120-140kts.

I also agree with Richard that when faced with an event like what we witnessed during Hugo, it is easy for anyone, regardless of their prior experience, to over estimate wind speeds visually. In fact, as it was happening, the three of us who were in Luquillo were all of the opinion that the peak gusts were up in the 160kt range...there's even a point in my video where Jim Leonard and I are talking and saying that the winds are easily gusting to "180" [mph]. After the adrenaline overload subsided, we both re-evaluated our estimates and, after almost 18 years of reviewing the footage, not to mention going through many, MANY other tropical cyclones...I can confidently say that the peak winds we experienced in Luquillo were sustained near 115kts with frequent gusts between 130-140kts and it is entirely plausible that an instantaneous peak gust reached 150kts. This estimation is not inclusive of the amplification in wind speed that did occur between the two condo towers, which you are completely correct in assessing.

I am curious, how many times have you personally been through the core of a major hurricane, and what are your qualifications for the visual estimation of windspeed?

I would also challenge that you truly gave this an "objective" look as you seem content that the sparse surface reports from Roosevelt Roads NAS and San Juan as well as the "best-track" positions of the storm described in the NHC Preliminary Report are sufficient to describe Hugo's strongest winds and exact position, relative to Luquillo...without even the possibility that there could be more to it than what is officially documented.

Again I'm curious, how well do you know Miles Lawrence, the man who wrote that preliminary report? How many years did you spend physically at the National Hurricane Center talking to him, or Bob Case, or Gil Clark, or Bob Sheets, or Neil Frank...or any of the other forecasters or directors through the years? How many times have you actually been on a chase with one of the forecasters from the National Hurricane Center?

The best track and the NHC report on Hugo state the maximum intensitiy to be 110 kt (127 mph) -- a Cat 3 -- not a Cat 4 -- at the time Hugo hit the island of Vieques, and again shortly afterwards when it hit mainland Puerto Rico.

Well then, I guess it is clear, if it is written on paper it must be fact! I would just note that, for ten years, what was written in the NHC's official report for Hurricane Andrew was that the storm was a Category Four with sustained winds of 125kts, at landfall...although many of us held fast that sustained winds were much higher...not surprisingly, that estimate was revised to 145kts. I will also point out that while the NHC reports use knots as their standard for best-track wind speed... the exact conversion of 110kts to 127mph, while correct, is not how it is reflected operationally...where the number is rounded up to 130mph. Thus, even in Miles' report, Hugo's intensity at the time it passed over Vieques and Northeast Puerto Rico is technically only 1mph shy of Category Four strength. So suffice it to say that even by your reasoning, Hugo was at the cutoff between Category Three and Category Four at the time I experienced it.

Hugo was travelling northwest, and made landfall just on the very northeast corner of Puerto Rico as it passed. The lat and lon of the best track shows the center of Hugo moved past to the northeast of Luquillo...

The geometric center of Hugo did indeed cross the extreme northeastern tip of Puerto Rico, just north of Roosevelt Roads from Fajardo through Luquillo. A ragged portion of the northeastern eyewall is briefly visible offshore, on my video, as we exit the eye and enter the southeast portion of the storm. The "best-track" positions in the NHC report are an averaged/smoothed track and do not represent the actual physical location of the circulation center at any given time.

You are partially correct that northwestern eyewall impacted Luquillo, though it was really more the area between the northern and northwestern eyewall that moved over our location.

The strongest winds of the hurricane were likely located in the typically-more-powerful portion of the hurricane to the right of the forward movement, not in the portion of the eyewall that passed over Luquillo. At the time Hugo was moving northwest, so the strongest winds would likely have been...offshore and well to the east of Puerto Rico.

As Richard also previously pointed out, a tropical cyclone's surface windfield distribution can be highly variant to the "typical" right-front quadrant conventionality, as observed in numerous instances. At any given time, the wind maximum can even be transient, with the development of intense convection in any quadrant. Though detailed radar analysis of Hugo crossing Puerto Rico has been elusive, some satellite imagery (like on the cover of this Natural Disaster Survey Report) near the time the storm moved over Luquillo showed the most intense convection from the northern through southwestern eyewall, as evidenced by the brighter, more bulbous, convective tops. Since the north and northeastern extremity of this "hot spot" in the eyewall is what would have passed over Culebra, with the northwestern portion passing over Vieques and later over my location...this is what I'm referring to when I mention that the "strongest portion of the eyewall passed over my location".

As already mentioned Hugo was not a Cat 4 at landfall in Puerto Rico, but a Cat 3. Peak windspeeds were determined to be 127 mph (110 kt), but likely remained offshore.

Again, your reasoning, while solid from a conventional analysis of the limited data provided through the NHC report, is not consistent with what our chase team experienced. Additionally, your assumption that the strongest surface winds remained offshore is neither substantiated by the NHC report, let alone "likely" based on the presence of the most intense convective activity over the northwestern portion of the eyewall...since that convection would likely be bringing the higher winds aloft, down to the surface.

<<Continued>>
 
Hubris indeed! (Continued)

<<Continued>>

This gust of 148 kt (170 mph) on the island of Culebra was actually a significant distance away: about 25 miles due east of Luquillo, and to the east of the eye. The portion of the storm that passed over Culebra would have continued on the northwest track, and so by the time it was as far west as Luquillo, would have been far away, around 25 miles to the north of Luquillo. And the NHC report does not state the time the gust occurred. The fact that the highest recorded gust occured to the east of the eye supports the premise that the strongest winds were associated, as usual, with the northeast quad of the storm, and remained offshore of Puerto Rico.

A couple of things that you are failing to mention/acknowledge... first, the 148kt gust from the yacht "Night Cap" was reported just prior to the anemometer failing, so it is plausible that even higher winds occurred at that location and were not recorded. Miles Lawrence inexplicably left this detail out of the report. Second, your assumption that just because this is the highest "reported" wind, that this represents the location of the highest winds in the storm is flawed... while it is certainly possible... it is just as possible that higher winds existed elsewhere in the eyewall and/or that the wind maxima was uniformly distributed from the northern through western eyewall, or possibly split into two areas of wind maxima, or even transiently rotating within the eyewall. Indeed a 700mb wind-field analysis from 17/20Z through 18/06Z indicated that the peak winds were distributed from the eastern through northern eyewall, coinciding with the location of the most intense eyewall convection at that time. Subsequent to that, the most intense convection apparently migrated to the northern through western eyewall and this supports the premise that the surface wind maxima likely followed and rotated from the eastern through northern portions of eyewall to the northern through western portions of the eyewall, impacting both Culebra and Northeastern Puerto Rico, in turn.

However the northwestern eyewall that passed over Luquillo, did pass over another area of Puerto Rico prior to crossing Luquillo, with documented windspeeds. This was a US Naval Air Station to the southeast of Luquillo. The official readings were labeled "Roosevelt Roads." The maximum sustained windspeed there was 104 mph (90 kt), with a gust to 120 mph (104 kt) -- solid Cat 2 winds. This was the highest sustained windspeed noted over land in Puerto Rico.

It is actually likely that it was the western eyewall that impacted Ceiba and Roosevelt Roads NAS. That said, the direction of the strongest winds in this area (also absent from NHC's report) was likely from the north-northwest or northwest, meaning that 1. these winds were from an over-land direction, as opposed to onshore... and 2. they would have been partially blocked by the moutainous terrain of the El Yunque peak. Again, you are correct that this is the highest "recorded" wind speed from a land station in Puerto Rico, however, if your assumption is that Roosevelt Roads observation happened to record the strongest winds anywhere in Puerto Rico, and that this alone substanstiates your claim that winds were no stronger than Category Two intensity anywhere on the island, I would suggest that you re-examine your methods of analysis.

Also of note is that the minimum pressure at Roosevelt Roads was 946.1 mbar, and occured at 1250Z. The minimum pressure at Luquillo was 956 mbar, noticeably higher, and that occured ten minutes later at 1300Z.

You are absolutely correct...the minimum pressure reported in Luquillo was indeed 956mb... BECAUSE IT WAS OUR CHASE TEAM'S OBSERVATION! You can actually see Jim Leonard's barometer, which is what the observation was made on, in my video. As such, I think I am qualified to say that the reading of 956mb was made significantly after the mid-way point in the lull. We had been walking around filming damage, in the eye, for nearly 30 minutes before returning to the garage where our car was, just before the second-half started. This is when the observation was made. Just because the lowest pressure we observed at that point was 956mb, doesn't mean that the pressure wasn't lower earlier during the eye. As you point out below, even the NHC report indicates that the pressure at landfall in Fajardo (just to the east of Luquillo) was 946mb, which is probably closer to what the minimum pressure at our location actually was. This just goes to highlight that not all documented data can be taken at face value.

For those who find these things as facinating as I do, and are interested in taking a closer look, I provide the link to the NHC Hugo report, the recon obs, and the relevant best track points below, which can be plugged into Google Maps -- which also provides a quick and easy way to look at the various locations that were mentioned.

18/0600Z 17.7N 64.8W 940 mbar 110 kt
18/1200Z 18.2N 65.5W 945 mbar 110 kt
18/1800Z 19.1N 66.4W 958 mbar 105 kt
19/0000Z 19.7N 66.8W 959 mbar 100 kt

Luquillo is located at 18.375N 65.715W. Landfall on the Puerto Rican mainland was identified in the NHC report as being at Fajardo, at 18/1300Z, with a pressure of 946 mbar.

I want to reiterate that although I do not necessarily agree, I completely respect your opinions. Based on your previous posts, I know that you have a great understanding of tropical cyclone dynamics. I just ask that before you make public claims of hubris, that you give the appropriate respect and weight to the opinions and observations of people who had first-hand experience and have spent years dedicated to understanding every nuance of that encounter with Hugo. And, also to allow for the possibility that empirical observations alone do not always paint the complete picture.

As a direct observer, I know Richard Horodner has already provided his perspective, and I would love to see Jim Leonard's views on this topic. I would also encourage anyone, who is interested, to watch my video and share their perspectives and views.
 
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Michael, I thank you for a really excellent reply to my posts, and will definitely want to continue this facinating discussion. As regards hurricane dynamics or any other TC topic, I know nothing by comparison -- but I'm working very hard to increase the range of my ignorance (equations...are your friends). If I could ever remember to play the lottery I might be looking for a grad school for old people. :)

But it will have to wait until this evening...I'm going to try to get a quick post out on the rapid intensification of Favio, and then address some interesting problems at work.
 
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Margie is correct to reference the best track analysis rather than the operational analysis. RSMC Miami and the other RSMCs/TCWCs spend significant time re analysing all the systems after they have occurred. Quite a few had changes from RSMC Tokyo last year for example. They have far more time than they do when also forecasting the track and writing all the advisories etc and also gives more time to gather data.

Yes Katrina was a high cat 3 at first landfall (110kts, 204km/h), they had several reconnaissance aeroplanes in it at that time so had a pretty good dataset compared to other TCs. It looked to be a cat 3 to me at the time based on the HDOBs and so on. Operationally it was held as a cat 4 until 1500 GMT on the 29th August by which time it was making landfall for the second time (Excluding landfalls before the 28th August). The BT in the tropical cyclone report has it down to a cat 3 by 1110GMT on the 29th August.

The Bernoulli effect will happen of course between buildings allowing the wind to be funnelled and so increased. Friction is also much greater over land than it is over the ocean. You don't have to go up very high for the winds to increase by a category or two so being at the top of a tall building in a TC isn't a great idea obviously.
 
A quick post to note that it looks like I sure did mistype the 110 as a 120 for the 06Z; my apologies. I was including prior track points for the lat lon to show the NW movement and that was definitely not intentional (I'm a real stickler for accuracy...but not the greatest typist with the number keypad). The 06Z intensity, six hours earlier, in any case doesn't really have anything to do with the Puerto Rico landfall, as the eyewall winds would have been miles away at that time (pounding St. Croix). Remember the context of the video...the strongest winds were some time after it became light outside. There was a lot of filming during daylight from various locations prior to the onset of the highest winds. When is sunrise that time of year in Puerto Rico? --around 10Z. And even if some of the video was shot from as early as 10Z (6am -- and it appears there was some footage around that timeframe) the strongest winds came some time after. Therefore the winds from the eyewall were right around the time of landfall, or just prior, probably 12Z to 13Z, as you'd expect. Remember that vmax was determined to be 110 even earlier than the Puerto Rico mainland landfall -- at the Vieques Island landfall at 12Z.

Note: I did a quick review of the minobs before my original post. I could find no data to support the highest winds in the western eyewall at any time near the landfall, or to support any winds of Cat 4 or Cat 3 intensity over eastern Puerto Rico or nearby. But I didn't take a look at the dropsondes, so someone with more time, have at it. :)
 
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You've got a point on the BT, I'd not checked the HURDAT file but it looks like you are correct. That time gives a sustained wind of 120kts with a centre pressure of 940hPa.

53685 09/10/1989 M=16 08 SNBR=1139 HUGO XING=1 SSS=4
53690 09/10 *1320200 25 1010*1330218 25 1010*
53695 09/11*1320237 030 1009*1300255 030 1007*1280273 30 1005*1250292 35 1003*
53700 09/12*1250310 040 1002*1250329 045 1000*1250348 045 998*1260367 50 0996*
53705 09/13*1260382 055 994*1270400 055 992*1280418 060 990*1280435 65 0987*
53710 09/14*1290449 070 984*1300463 080 980*1320478 085 975*1360491 90 0970*
53715 09/15*1380505 100 962*1400519 110 957*1420533 125 940*1460546 140 0918*
53720 09/16*1480561 135 923*1510573 130 927*1540584 120 940*1580594 120 0941*
53725 09/17*1610604 120 941*1640615 120 943*1660625 125 949*1690635 125 0945*
53730 09/18*1720641 130 934*1770648 120 940*1820655 110 945*1910664 105 0958*
53735 09/19*1970668 100 959*2070673 090 962*2160680 090 964*2260686 90 0966*
53740 09/20*2350693 090 957*2440701 090 957*2520710 095 958*2630722 95 0953*
53745 09/21*2720734 100 950*2800749 100 950*2900761 110 948*3020775 120 0944*
53750 09/22*3170788 120 935*3350803 085 952*3590817 055 975*3850818 40 0987*
53755 09/23E4220802 035 988E4600745 040 990E4900690 040 992E5100650 40 0993*
53760 09/24E5200620 040 994E5250605 040 993E5300595 040 991E5350585 40 0989*
53765 09/25E5400570 040 983E5600520 040 979E5800460 040 974
53770 HR SC4

One other point on MK's last posts. She used an "analogy" to try and make her point about Hugo: stating that the NHC will not lower the category immediately prior to landfall. The forecaster , positioned the eye 45 miles wSw of Biloxi. This is offshore.
He also lowered the max winds to 125 mph. Hence: he thaught the eye was offshore, but still lowered the category.

Even if the post analysis times landfall at 9:45 (whether that is the center of the eye or the northern edge of the eye is another question), the analogy example is supposed to show that the NHC does not lower the category before landfall. The NHC at the time of the advisory writing, was going under the assumed data that the eye was still offshore. They lowered the category on that advisory. The analogy indicates the opposite of the hypothesis.

The 0000, 0600, 1200, and 1800 positions in the BT are not the same as the positions in the advisories. The advisories are issued at 0300, 0900, 1500, and 2100 and these positions are three hourly forecasts based on the positions at the times above used in the BTs all over the globe. The intensity of the later times is also usually decided from the former times.
 
Michael, I'm finally geting an opportunity to provide more information that I have researched on Hugo.

Regards the IR image you mention, since it is a copy of a front page of a document that was itself a copy of an IR satellite image, it would be hard to analyze the strength of the convection, even if the scale were also visible in the image. Also, that was taken ten hours prior to the time the Hugo's eyewall affected Luquillo, where you were located in Puerto Rico...and many changes occurred during that time, which makes any conclusions about the relative strengths of the various quadrants ten hours later impossible to tie to this particular satellite image. I do however have two IR satellite images that I’ll link to in this post that are color images and do provide more of a comparison of the strength of the storm between the 17th and the 18th.

I reviewed the more recent Commission on Engineering and Technical Systems (CETS) 1994 report, which uses some material from the earlier NOAA report, but which also provides an extensive engineering analysis, as well as additional meteorological information. The report noted the sparse observations but did not find this impeded their damage analysis.

What I'd like to do is to present a broader picture of what was happening with Hugo on the afternoon of the 17th, and the 18th, to provide a context for understanding maximum sustained windspeeds (all given in 1-min. averages) in relation to the timing of your video.

First, let’s review the maximum sustained winds from the best track times:

18/0000Z 17.2N 64.1W 934 mbar 130 kt
18/0600Z 17.7N 64.8W 940 mbar 120 kt
18/1200Z 18.2N 65.5W 945 mbar 110 kt
18/1800Z 19.1N 66.4W 958 mbar 105 kt
19/0000Z 19.7N 66.8W 959 mbar 100 kt
19/0600Z 20.7N 67.3W 962 mbar 90 kt

Do you see the trend? Pressure increasing at every track point, and vmax falling with every track point? Take a look at the mslp-vs-time and vmax-vs-time graphs from the Hugo best track. Hugo weakened for 48 straight hours, from 18/00Z to 20/00Z then strengthened from 20/00Z to 22/00Z, prior to landfall in South Carolina.

Now there are two NOAA images in the photo archive that are key in capturing the differences between Hugo when more powerful, just prior to landfall in St Croix, at 00Z on the 18th, and after weakening, during landfall in Puerto Rico, at 1330Z on the 18th.

wea00450.jpg


wea00451.jpg


Note the dramatic differences between the two images, taken only 13 1/2 hours apart. In the first image, the eye is clearly discernable, but in the second image, it has filled and cannot even be seen. However San Juan radar fixes showed it to be about five miles offshore, due east of the northeastern tip of Puerto Rico at that time (and just at that same time, mid-morning, you were filming the eyewall coming ashore). Also the structure of the CDO is no longer uniform and the cloud tops have warmed since the earlier image.

Now, look at the path of the center of the storm as tracked by the San Juan radar fixes:

p200046c9g30001.jpg


That movement is called trochoidal movement, and it is another big tip-off to what was going on inside Hugo. You probably know where I’m going with this now: the recon first reported a double concentric eyewall at midday on the 16th.

Hugo underwent an eyewall replacement cycle (ERC) starting at about 18Z on the 16th, and finishing at around 00Z on the 20th, after which time, the ERC having completed, intensity increased up until landfall. It is well-known that during the restructuring of an ERC, intensity usually falls, sometimes quite rapidly. Where have we seen this most recently? Just days ago, with Favio, where satellite intensity estimates from JTWC dropped from 125 kt at 00Z to 90 kt at 19Z on the 21st – in less than a day. Both of these TC weakened from a Cat 4 to a Cat 2 during the ERC.

Hugo's ERC was particularly messy, taking a long time to complete, and depending on the position of the partially-open inner eyewall in relation to the outer eyewall, at times only the outer wind maximum was noticeable (in the context of 1989, prior to a more complete understanding of ERCs, the size of the eye appeared to “grow” and “shrink”).

The trochoidal movement mapped on satellite or radar imagery occurs when what is left of the disintegrating inner eyewall rotates around inside the outer wind maximum that is becoming the new eyewall, while the storm is moving forward. This easy-to-spot trochoidal movement can be seen in reviewing images of Wilma on the NRL web site, using the animate feature, during a time period prior to landfall at Cozumel, when the ERC was completing. It can also be seen on a radar loop of Katrina when making landfall on the northern Gulf Coast.

I’ll provide more details about the winds in Hugo, and when they occurred during this period of weakening, in a subsequent post.
 
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IR Images, Survey Reports and ERC's

Hi Margie - To be fair, we have had a significant amount of e-mail exchange between the time of your last post in this thread and today. And it is only fair that other readers get to review the data that I shared with you outside of this thread. I'll post some of that a little farther down.

Regards the IR image you mention, since it is a copy of a front page of a document that was itself a copy of an IR satellite image, it would be hard to analyze the strength of the convection, even if the scale were also visible in the image. Also, that was taken ten hours prior to the time the Hugo's eyewall affected Luquillo...and many changes occurred during that time, which makes any conclusions...impossible to tie to this particular satellite image.
I do admit that changes in the structural organization of Hugo could have taken place between the time of the IR image on the cover of the report, and when Hugo moved over northeastern Puerto Rico. That said, this image is not 10 hours prior to the time Hugo's eyewall impacted Luquillo. Our chase team entered Hugo's eye at approximately 0900 AST, and the northwestern eyewall had impacted us for approximately an hour and a half prior to that...so assuming that the eyewall began at 0730 AST and the IR image from the Survey Report is at 0208 AST, this is about 6 hours prior to the worst weather impacting Luquillo. While this may mean it is difficult (though not impossible) to tie formal conclusions about any potential structural changes to this one image, your comment that "...many changes occurred during that time" [presumably the time between the survey image and the second IR image you have posted] is just as difficult to formalize, since you are apparently basing your assumption on two premises... 1. that there is a significant difference in the presentation of Hugo between your first image and your second...to that, of course there is a significant difference... in the first image Hugo is over water southeast of St. Croix and in near it's peak intensity in the Caribbean...in the second image, the center has just moved offshore northeastern Puerto Rico and the storm is weakening. 2. that it is difficult to analyze the IR image from the survey report cover, because it is a copy of a copy...that may be, but this image is certainly more detailed than the colorized IR image you posted below. I certainly have no trouble locating the most intense convective tops over the northern through western eyewall in the survey report image. Either way, I submit the following comparison, between the second IR image you posted and the one from the survey report...

hugo_ir_comparison.jpg


...as best I can tell there is very little, if any, structural difference between the two...other than the fact that the 1030 AST image is after the core of the storm has already interacted with the mountainous terrain of Eastern Puerto Rico and has begun to fill. With this, I stand by my prior conclusion that the strongest eyewall convection from at least 0200 AST through landfall, was located over the northern through western quadrants and impacted Northeast Puerto Rico from Fajardo to Rio Grande, including my location in Luquillo.

While I think that the CETS report may indeed have some definitive conclusions, the overarching goal and findings of the original Dept. of Commerce/NOAA Natural Disaster Survey Report is probably more relevant to this particular debate. Here is some additional information from that report:

The 13-person survey team was comprised of representatives from NOAA, NWS, NOAA-ERL and NESDIS. The goal of the report was documentating "an objective appraisal of Hugo's impacts" as well as presenting findings and recommendations. The report was published in May, 1990 (note that this is fully six months after the NHC published their preliminary report and best-track data for Hugo in November, 1989...so the NHC data was well known to this commission). The survey team's findings and conclusions are of significant interest to this debate, since they deal specifically with the Hugo case-study and, in my opinion takes a much more "evaluative" approach. In some cases the findings and conclusions from this report stand in stark contrast to other "official" documents on Hugo. Here are some excerpts:

Pg 1 - Chapter I - Hurricane Hugo: The Event and its Impact - "At one point east of Guadeloupe, a NOAA research aircraft measured winds of 160 MPH and a central pressure of 27.1 inches (918mb) which rated Hugo as a Category 5 -- the highest -- storm on the Saffir-Simpson Scale. When Hugo struck the Virgin Islands, Puerto Rico and the Carolinas, it was classified as a Category 4."

"...A couple hours after midnight Monday, September 18, the hurricane's eye crossed the southwestern coastline of St. Croix near Frederiksted severely damaging this Dutch-style town. Maintaining 140 MPH maximum winds, the hurricane destroyed or damaged more than 90 percent of the buildings on St. Croix...Based on the Fujita Tornado Intensity Scale (see Appendix C), damage surveys indicated that there was widespread upper (F1) and (F2) straight-line wind damage. Thus, wind speeds as high as 161 MPH were estimated. Some localized damage appeared to be (F3) but might have been caused by topographic channel effects or microbursts."

"After sunrise Monday, September 18, the hurricane increased its forward speed as it crossed over the Puerto Rican islands of Vieques and Culebra and skirted the northeast tip of Puerto Rico near Fajardo. As the eye passed over Vieques, maximum winds were estimated at 132 MPH. At Culebra just north of Vieques, an unofficial gust of 170 MPH was reported by the yacht, Night Cap."

Pg 4 - Chapter I - Hurricane Hugo: The Event and its Impact -"On Puerto Rico proper, peak gusts at Roosevelt Roads Naval Air Station, 10 miles south of Fajardo, were recorded at 120 MPH. Sustained winds hit 98 MPH. The hardest hit areas were Fajardo and Luquillo Beach on the northeast coast where damage paralleled that of St. Croix."


Do you see the trend? Pressure increasing at every track point, and vmax falling with every track point? Hugo weakened for 48 straight hours, from 18/00Z to 20/00Z
I'm not sure what the point is here? There has never been a debate about wether Hugo was on a weakening trend...clearly the storm weakend between the time that it crossed St. Croix and when it moved over Vieques and later NE Puerto Rico. What is in question is the intensity of the storm at, and just prior to, landfall in Puerto Rico and what the maximum sustained surface winds and gusts in Luquillo (and subsequently on my video) are. My conclusion (and the conclusion of the DOC/NOAA survey team) was that even though the storm was weakening, it was still a category four when it moved over both Vieques and Puerto Rico...with maximum sustained (1-min) surface winds likely weakening from 120kts (140mph) over St.Croix to 115kts (135mph) over Vieques/Puerto Rico. This is consistent with the survey team's finding: "As the eye passed over Vieques, maximum winds were estimated at 132 MPH". Note that in all instances in the report, they are using the exact conversion of knots to mph, rather than rounding up to the nearest 5mph, which is what is done operationally. Of more importance is what the damage survey yielded, that within the area from Fajardo to Luquillo Beach, "damage paralleled that of St. Croix", where extensive upper F1-F2 damage was observed, with some localized areas of F3 damage, which may be attributed to microbursts. Regardless, this indicates that as far as the DOC/NOAA disaster survey team was concerned, peak winds (gusts) up to 140kts (160mph) occurred in the area between Fajardo and Luquillo...and this is completely consistent with what I have been saying all along... in Luquillo, our chase team experienced maximum sustained (1-min) surface winds of 115kts (135mph), with gusts to 130-140kts (150-160mph).

That movement is called trochoidal movement, and it is another big tip-off to what was going on inside Hugo. You probably know where I’m going with this now: the recon first reported a double concentric eyewall at midday on the 16th.
Again, I'm uncertain of the relevance to this specific debate. Cyclodial looping of the circulation/wind center's path is not specific to instances of an ERC, a pronounced trochoidal deformation of both the circulation center and/or pressure center can occur for a variety of reasons, even when the geometric center of the storm does not appear to be affected and continues moving on a relatively steady state.

Hugo underwent an eyewall replacement cycle (ERC) starting at about 18Z on the 16th, and finishing at around 00Z on the 20th
Unless you have access to some detailed radar analysis for Hugo (that I'm unaware of), I have no idea how you are inferring that a prolonged 3-day ERC event took place. I have no doubt that an ERC or multiple ERCs occurred with Hugo during that time...possibly even at, or near, the time of Hugo's landfall over Vieques and NE Puerto Rico...indeed the survey report IR image clearly shows a broad central area. That said, even if this occurred, and it was an outer wind maxima that moved over NE Puerto Rico, it doesn't automatically mean that Hugo was below category four intensity at that time....or that the winds in Luquillo were anything less than what I have previously described.
 
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"When Hugo struck the Virgin Islands, Puerto Rico and the Carolinas, it was classified as a Category 4."

Michael, that's just simply incorrect as regards the Puerto Rico landfall. It contradicts the best track information, which was available at the time that report was written. Besides it is just one of the inaccuracies in that document (for instance, on their map of the islands, they labeled Vieques as Culebra and vice versa). The 1994 document is much more complete, and for the first time thoroughly evaluated all the wind information and tracked wind reports down to the source.

I'll try to get a chance to provide the more detailed wind information today.
 
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Hi Margie - To your points below....
"When Hugo struck the Virgin Islands, Puerto Rico and the Carolinas, it was classified as a Category 4."

Michael, that's just simply incorrect. It contradicts the best track information, which was available at the time that report was written.
When I previously quoted the DOC-NOAA report, I qualified that their conclusions stood in stark contrast to other "official" documents, including the NHC preliminary report/best track observations. My entire point was not to say that either the DOC-NOAA report or the NHC preliminary report are the "final word" on Hugo, but to illustrate that there is significant variance across many "official" documents on Hugo and that this, and our current debate, continues to show that deliberations on Hugo's intensity over Puerto Rico will continue among professional and amateur meteorologist for quite awhile. To say that it is "simply incorrect" is just a point of view...as there is room for speculation within all of these documents. Personally, I am hoping that the HRD re-analysis effort, that has been underway for the last few years, will ultimately revise Hugo's best-track intensity (up to 115kts) at the time it was over Vieques and Fajardo. Regardless, as for that same question in our current discussion, I will agree to disagree, since it seems unlikely that either of us will be convinced otherwise. :)

Besides it is just one of the inaccuracies in that document (for instance, on their map of the islands, they labeled Vieques as Culebra and vice versa).
Figure 2-1 on page 10 (Decision arc methodolody) is a generic map that has been used in numerous publications from the mid-70's on and is in no way specific to Hugo. That said, you are correct that the labels for "Vieques" and "Culbera" are transposed on this one graphic...however, this is a flaw from the original image, not an inaccuracy from the authors or in the meteorological data, findings or conclusions in the document. So it makes no sense to try and imply that this invalidates the work done in this report.

Furthermore, if you do want to look at more serious inaccuracies or disparities that do impact final conclusions...let's look at the 1994 document that you are referencing:

[On page #54 - Referencing the advancement of Hugo's rainshield over Puerto Rico, the author, Joseph Golden (et al), notes: "The rainshield moved eastward at about 20 mph from midnight September 17 to 0200 AST September 18 over northern Puerto Rico, but after the first hour the forward movement was retarded in the southern parts."]
Obviously this is should be "...moved westward"... as Hugo's rainshield was propogating westward with time as the storm approached Puerto Rico. Additionally, a similiar reference in the previous paragraph does have the direction correct...so this is clearly an oversight.

[On page #38 - Referencing Surface Wind-Speed Observations, the author notes: "An unofficial estimate of winds gusting to 150 knots (173 mph) in the harbor at Culebra was made by a mariner who rode out the storm on his sailboat and videotaped his anemometer."]
As noted in both the NHC preliminary report and the DOC-NOAA survey, the correct value, from the yacht Night Cap, was actually 148kts (170mph). So it is unclear if this is simply a typographic error, whether the authors felt it was acceptable to be ambiguous about this value, or whether there was some additional qualitative data to support changing the value (though no specific references are cited to support that). It is extremely interesting to note that they indicate the observer "videotaped his anemometer"...if anyone reading this has ANY idea if/where a copy of this videotape exists, please let me know.

[On Page 35 - Referencing Mesoscale Changes in Storm and Structure, the author notes: "Hugo's ill-defined eye moved north-northwest after hitting the northeast coast of Puerto Rico (Figure 1-13), and by noon on September 19 was over open water north of San Juan with maximum sustained winds of 109 knots (125 mph) and minimum sea-level central pressure (MSLP) of 957 mb."]
I'm not even sure where to begin with this one...apparently the author got the entire DATE wrong, as it appears he is referring to noon on September 18th, as by the 19th Hugo was well past Puerto Rico. So overlooking that the date is incorrect, and assuming he meant noon on the 18th, the NHC best track intensity for this time is 105kts (120mph)...so if I am to be as stringent as you are with adhering to the "official" NHC best-track intensities for Hugo as the basis for invalidating other reasearch documentation and findings (i.e. the 1990 DOC-NOAA survey), then I'll have to assume all of your citations from the 1994 CETS document are "simply incorrect", without merit, and the entire document should be disgarded on the basis of numerous inaccuracies. Obviously I really don't feel this way about the CETS document, which is an incredibly important and detailed piece of work...but I just want to make sure that the playing field for our debate is truly level.

[On Page 36 - Referencing Unique Observations, the author notes: "A storm chaser was able to position himself in a multistory condominium in Luquillo and produced a remarkable videotape of the approach and passage of Hugo's eye directly over head. The videotape documents damaging wind and rain effects on nearby structures during major rainband and eyewall passages in Hugo, as well as the chaotic state of the adjacent sea surface. He used a digital barometer to measure a lowest pressure (956 mb). San Juan, which remained outside the eye, recorded a minimum pressure of 970.3 mb. The radar sequence in Figure 1-14 supports the pressure data indications that Hugo was filling as it crossed the northeast coast of Puerto Rico. However, it must be emphasized that the western eyewall passed just to the east of metropolitan San Juan, probably affecting Loiza and Pinones (Figure 1-11, Figure 1-12 and Figure 1-13); moreover, this geometry is entirely consistent with the large gradations of damage and surge effects (especially overwash) documented by the team from Catano eastward."]
Want to take a guess as to what "storm chaser" and videotape the author is referencing?!? So, as I already pointed out in a previous post, our chase team's observation of 956mb was made at the very end of the eye passage, when the pressure was already rising rapidly and likely does not represent the lowest pressure that occurred in Luquillo, which was probably closer to 946mb, 15-20 minutes prior to our 1300 UTC observation. The author's conclusion that Hugo had filled by 10mb, based partially on the "face-value" of our observation, really is..."simply incorrect".

The 1994 document is much more complete, and for the first time thoroughly evaluated all the wind information and tracked wind reports down to the source.

I totally agree that the 1994 CETS document is an amazingly detailed look at Hugo...what I would point out though is that this document should not be viewed simply as a replacement of any previous documentation (whether that be the NHC preliminary report in 1989 or the DOC-NOAA survey in 1990), but rather an additional piece of evidence to be used collectively with all other documents to make the most evaluative conclusions.

That said, while the 1990 DOC-NOAA survey takes a more hardline stance that Hugo was a Category Four over Puerto Rico, even in this 1994 document, there is significant ambigiuty...as examples:

[On Page 2 - "Hugo was a category 4 hurricane when it crossed the Caribbean islands. On Guadeloupe, about half of the capital city of Pointe-a-Pitre was destroyed. Severe damage also occurred on the nearby island of Montserrat. The U.S. Virgin Islands of St. Croix and St. Thomas were hard hit, with St. Croix experiencing an unusually prolonged battering of hurricane-force winds. Hugo crossed over St. Croix the evening of September 17 through the early morning of the 18th. Hugo then passed through Vieques Sound, between the islands of Culebra and Vieques, early on September 18 and moved over Puerto Rico around 0830 AST. After subjecting northeastern Puerto Rico to hurricane-force winds and rains and causing extensive damage, particularly in the San Juan area, Hugo was again over open water, heading for the mainland."]

[On Page 3 - "Before Hurricane Andrew in 1992, Hugo was the costliest hurricane endured by the United States. Monetary losses were over $10 billion, with about $3 billion of this damage in the Caribbean. St. Croix and St. Thomas suffered tremendous damage, as did the northeastern corner of Puerto Rico. San Juan, Fajardo, and Luquillo were hard hit, with Luquillo receiving the most severe damage."]

Many of the indications in this report continue to imply that Hugo was stronger over Vieques and Puerto Rico than the current NHC best-track data dictate. I'm looking forward to your more detailed analysis of wind information.
 
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The 1994 document is an update to the previous one that was issued just by NOAA -- or, probably more correctly, an expansion of the original document. The section on meteorology is written by the same person, but is clearly more detailed.

There is really nothing in that document that indicates a Cat 4 over Puerto Rico.

Yes I noticed that date is a typo -- that should have been the 18th. The information they quote is correct, that refers to recon from between 20Z and 21Z on the 18th. I have additional recon data to that one though that I'll be posting... sometime... soon...
 
The 1994 document is an update to the previous one that was issued just by NOAA -- or, probably more correctly, an expansion of the original document. The section on meteorology is written by the same person, but is clearly more detailed.
It is not simply an "update" or expansion to the previous document. It does use a lot of the same data, but while the majority of the body of data in the CETS report is primarily authored by Joe Golden (et al), this is not the case for the 1990 DOC-NOAA report where some data from Golden is incorporated, but Joe was not even part of the actual team, let alone the author? The primary authors specific to the information about Puerto Rico and the Virgin Islands in the 1990 DOC-NOAA survey were:

R. Augustus Edwards, III - Special Assistant to Dpty.Administrator, NOAA.
Edward M. Gross - Chief, Constituent Affairs Office, NWS.
Jose G. Meitin, Jr. - Meteorologist, Environmental Research Labs, NOAA.
Donald R. Wernly - Chief, Warning & Forecast Branch, NWS

This team was lead by: James W. Brennan - Deputy General Counsel, NOAA

...to try and say that it was the same person who wrote both documents, implies that author changed their mind about the findings and conclusions in the earlier 1990 DOC-NOAA document...which is not true.

There is really nothing in that document that indicates a Cat 4 over Puerto Rico.
[On Page 2 - "Hugo was a category 4 hurricane when it crossed the Caribbean islands. On Guadeloupe, about half of the capital city of Pointe-a-Pitre was destroyed. Severe damage also occurred on the nearby island of Montserrat. The U.S. Virgin Islands of St. Croix and St. Thomas were hard hit, with St. Croix experiencing an unusually prolonged battering of hurricane-force winds. Hugo crossed over St. Croix the evening of September 17 through the early morning of the 18th. Hugo then passed through Vieques Sound, between the islands of Culebra and Vieques, early on September 18 and moved over Puerto Rico around 0830 AST. After subjecting northeastern Puerto Rico to hurricane-force winds and rains and causing extensive damage, particularly in the San Juan area, Hugo was again over open water, heading for the mainland."]

Last time I checked, Puerto Rico is still a Caribbean island.

Yes I noticed that date is a typo -- that should have been the 18th. The information they quote is correct, that refers to recon from between 20Z and 21Z on the 18th.
Again, forgetting the inaccuracy with the date, please explain how the "information" is correct? You're citing that it refers to "recon from between 20Z and 21Z on the 18th" [presumably you mean flight level observations?]

Let's revisit:
[On Page 35 - Referencing Mesoscale Changes in Storm and Structure, the author notes: "Hugo's ill-defined eye moved north-northwest after hitting the northeast coast of Puerto Rico (Figure 1-13), and by noon on September 19 was over open water north of San Juan with maximum sustained winds of 109 knots (125 mph) and minimum sea-level central pressure (MSLP) of 957 mb."]

I'm having a hard time seeing where the reference to "recon from between 20Z and 21Z on the 18th" is made or implied? In fact...the author specifically says "noon" though it is unclear if this is AST or EST. Assuming EST, just to give your theory the benefit of the doubt for the latest possible time, 1200 EST would translate to 1300 AST...or 17Z on the 18th...but you're saying that Golden is refering to recon observations between 20Z and 21Z on the 18th, please explain how he is referencing recon data 3-4 hours in the future?

In my opinion, when a tropical cyclone report references "maximum sustained winds", unless otherwise qualified, it usually refers to the maximum sustained 1-min surface wind speed (i.e. maximum intensity) at that time. There is nothing in the citation above to indicate differently...and as I pointed out before, this is 4kts (5mph) higher than the NHC best-track intensity at the time.

Aside from this issue, what about the other disparities I noted previously? With a prior post you noted that the transposing of a label on a graphic in the 1990 survey document illustrated the inaccuracies of that document. And, with the 1994 report, you've commented on the date/intensity issue above...but what about the discrepancies with the direction of the rainsheild's movement; the unofficial gust at Culebra; or the conclusions drawn based on my chase team's pressure in Luquillo? Again I am not trying in ANYWAY to discredit the 1994 CETS report...just to point out that there are inaccuracies, disparities or omissions in all documents (including NHCs preliminary report and best-track data) and that there is continued credibility in the 1990 DOC-NOAA report as part of the overall body of research, findings and conclusions regarding Hugo.

I have additional recon data to that one though that I'll be posting... sometime... soon...
I'm looking forward to it.
 
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This started out as an observation, but turned into a very interesting exercise on its own.

This is a summary of information from the web, best track data, recon data, and a 1994 engineering report on Hugo. The 1994 report, which I’ll quote extensively in this time sequence of wind events, was directed specifically at assessing surface windspeeds from Hugo and relating the winds to a damage assessment. Here they cited their sources of data:

“Radar images recorded on film by the WSFO in San Juan were particularly valuable in establishing wind directions and the presence of intense rainbands during the passage of Hugo. WSFO radar began tracking Hugo southeast of St. Croix early on September 18 and provided essentially continuous tracking until Hugo passed out of range late in the day. Also of value in assessing the relative strength of Hugo and, hence, the intensity of surface winds, were estimates of central pressure and eye diameter presented in post-storm summaries prepared by the NHC (Lawrence, 1989). Other sources of information were the flight-level records obtained by NOAA and USAF reconnaissance aircraft, satellite data, wind damage observations, and reports by residents of the affected areas.

“In the following paragraphs is an assessment of surface-wind speeds for each of the major areas affected by Hugo. Also included is a description of the reported speeds and the final disposition of these reports. To be consistent with standard wind-speed measurement and reporting procedures, the speeds described in the following sections refer either to peak gusts or sustained speeds at a height of 10 m in flat, open terrain, typical of airport exposures. It is important to note that wind speeds measured under nonstandard conditions may differ widely from standard measurements.

“In order to gain some perspective of the severity of the estimated and measured surface winds, comparisons are made with design wind speeds specified by local and regional building codes in the Caribbean. Finally, the extraordinarily high surface-wind speeds reported for St. Croix and St. Thomas are cast in terms of mean recurrence intervals (MRIs) derived from a recent study of wind statistics for the Caribbean region.â€￾


This summary statement identifies the maximum sustained windspeeds determined by the report:

"Observed damage in the areas affected by Hurricane Hugo is in general agreement with the surface-wind speeds listed [below]. This damage ranged from superficial to total devastation. In general, the most damaging winds were located in the northeast quadrant of the storm. This quadrant was also where the most intense rainbands, as indicated by their radar reflectivity, were located."

Probable Maximum Wind Speeds

Location................Max Sust Wind (kt)..Gust (kt)
---------------------- ------------------ ------------
Virgin Islands:

St. Croix...............110.................135.............(Cat 3)
St. Thomas...............85.................105.............(Cat 2)

Puerto Rico:

Culebra.................105.................130.............(Cat 3)
Vieques..................95.................115.............(strong Cat 2)
Roosevelt Roads..........85.*..(90).........104.*..(110)....(Cat 2)
San Juan Int’l Airport...67.*..(72)..........80.*...(86).....(Cat 1)

* Denotes actual measurement, unadjusted for height; adjusted measurement following in parentheses
[added by me for clarity]

The report found the damage consistent with these windspeeds.

Note that this does not contradict the best track. The best track identifies the maximum sustained winds that are located somewhere in the storm and not necessarily sampled. This report, which carefully reviewed the damage in relation to the wind direction and thus the application quadrant of the storm, observed that the most damaging winds, i.e, the strongest winds, were in the northeast quadrant. The wind readings on mainland Puerto Rico, which were from the weaker western side of the storm, support that as well.

In conclusion, there is no evidence of sustained Cat 3 winds on the Puerto Rican mainland, either from direct ground measurements or recon data or by a very thorough post-analysis. In order to claim otherwise you would have to be rejecting, wholesale, all the ground measurements, recon obs, radar obs from San Juan, and a detailed engineering assessment of wind damage. That is not logical.

There is a suggestion that sustained winds slightly higher than 90 kt could have occured at Luquillo. Slightly could be bent to go so far as 96 kt, although that would be pushing it. Nevertheless, let's suppose that to be a reasonable, although unlikely possibility. That just puts you at the absolute threshold of Cat 3 sustained winds. There is no way that sustained Cat 4 winds can be construed from such a situation.

Your video was a good video, without the hyperbole. Why do the winds you videotaped at Luquillo "have to be" Cat 4 sustained winds when it is simply not a possibility?

- - - - - - -

[part 2 and part 3 in subsequent posts -- I hit the size limit]
 
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I’m going to provide the various detailed information on location and wind speeds in chronological order. Notice how, as time goes on, pressure readings consistently rise and wind speeds fall. Hopefully this will clarify the intensity of winds around the time of the video at Luquillo. If not, there is no other detailed information I have access to at this time to provide. And I think I would be too worn out to write any more on this topic! :)

Time sequence on the 17th and 18th (UTC, which is AST/EDT+4):

On the afternoon of the 17th recon starts to observe concentric eyewalls.

A composite recon wind plot from late on the 17th, 2251Z (which would include values from a few hours earlier), shows 135 kt winds in the eyewall on the east and north legs; the northern leg is positioned in the right front quad of the NW-moving Hugo. Hugo is strengthening. This is seven hours before the center landfalls on St. Croix, although eyewall winds will start to effect them by around 0415Z.

p200046c9g35001.jpg


0000Z Best track records document Hugo has intensified to 130 kt just prior to approaching St. Croix.

0000Z best track:
center position 17.2N 64.1W, about 50 nmi ESE of St. Croix
pressure 934 mbar
intensity 130 kt

A recon vortex fix at 0312Z at 17.43 -64.50, or about 20 nmi SE of St. Croix, measures a pressure of 935 mbar, a circular closed eyewall 18 nmi in diameter, but noted the max flight-level wind was measured much earlier, 113 kt at 2320 in the south quad.

A recon vortex fix at 0526Z at 17.58 -64.73, or about five miles south of St. Croix, measures a pressure of 939 mbar, an elliptical eyewall stretching 25 nmi by 15 nmi east to west, opening to the SE, and a max flight level wind of 125 kt in the east quad at 0518Z (at the borderline between Cat 3 / Cat 4 intensity).

Best track records starting with 06Z note that Hugo has begun to weaken.

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St. Croix:

0600Z best track:
center position 17.7N 64.8W, just onshore St. Croix
pressure 940 mbar mbar
intensity 120 kt

from about 0700Z to 0900Z, eye executes a trochoidal loop keeping St. Croix in the strong northeastern eyewall for several hours.

“Wind damage on St. Croix was strikingly similar to that observed at Darwin, Australia, following Cyclone Tracy (Marshall, 1976). For the Darwin subdivisions experiencing the heaviest damage, the peak gusts averaged 135 knots (155 mph), and it is considered likely that the peak gusts on St. Croix were of similar magnitude. Analyses of numerous stripchart records from Hugo in South Carolina and from previous Atlantic and Gulf Coast hurricanes indicate that the ratio of peak gust to corresponding sustained speed is in the range 1.20 to 1.25. Therefore, if 135 knots is representative of the maximum gusts, the corresponding maximum sustained wind speed on St. Croix would be approximately 110 knots (127 mph). Because of the accelerating effect of the terrain on surface winds near Christiansted, wind speeds based on observed local damage would tend to be overestimated.

“An independent estimate of surface-wind speeds can be obtained from data collected by reconnaissance aircraft at the 700 mb level. These data indicate maximum speeds of about 130 knots (150 mph) during Hugo's passage over St. Croix (Lawrence, 1989). Data presented by Powell and Black (1989) suggest that the ratio of the 10-min mean speeds at 10 m over rough water to the 700 mb flight-level speeds is approximately 0.7, which in this case yields a 10-min mean speed of 90 knots (104 mph). Again, from the analyses of stripchart records mentioned above, the ratio of the maximum sustained speed to the corresponding 10-min mean speed in flat, open terrain is approximately 1.2. Thus, the corresponding sustained speed for standard exposure conditions is about 110 knots (127 mph).”


The report concluded the maximum sustained winds at St. Croix were 110 kt (strong Cat 3 intensity).

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Vieques, Puerto Rico:

1130Z center passes the very eastern tip of Vieques.

“The highest measured wind speeds on Vieques were gusts of 85 knots (98 mph) recorded at the U.S. Navy's Isabel Segunda facility by the 9-m anemometer mast just prior to its failure at approximately 0900 GMT. Comparisons of damage on Vieques with damage at Roosevelt Roads Naval Station, where a verifiable wind-speed record was obtained, suggest peak gusts of approximately 115 knots (132 mph) and corresponding sustained speeds of 95 knots (109 mph).”

The report concluded the maximum sustained winds at Vieques were 95 kt (strong Cat 2 intensity).

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Culebra:

“It was during the last few hours of Hugo's approach to Puerto Rico that Culebra probably experienced the worst wind effects…An unofficial estimate of winds gusting to 150 knots (173 mph) in the harbor at Culebra was made by a mariner who rode out the storm on his sailboat and videotaped his anemometer.”

“Strong winds from the northeast began to affect Culebra at about 0900 GMT when Hugo was located approximately 75 km to the south-southeast. Data from San Juan radar indicate that intense rainbands began to move over Culebra from the northeast at 1020 GMT. The wind direction changed from northeast to east as the eye began to engulf Culebra at about 1130 GMT. At this time the circulation, as indicated by the radar reflectivity of the rainbands, became less well defined, making it difficult to establish accurately the position and diameter of the eye. In fact, one eyewitness at Ensenada Honda on the south side of Culebra claimed that no lull was observed during the passage of Hugo. This same source reported a peak gust of 140 knots (161 mph) at 1130 GMT. The anemometer in this case was mounted on the mast of a boat that had been driven aground in Ensenada Honda approximately 1/2 hour earlier.

“The central pressure continued to rise as Hugo moved past Culebra, reaching 956 mb at 1300 GMT. Based on the observed damage, the storm track relative to the island, and the steady weakening of Hugo after it passed St. Croix, it is estimated that peak gusts of 130 knots (150 mph) and maximum sustained speeds of 105 knots (121 mph) for standard exposure conditions were experienced on Culebra”


The report concluded that the maximum sustained winds were 105 kt (Cat 3 intensity), from the stronger eastern side of the storm, and discounted the claims of gusts higher than 130 kt (150 mph). Note in the subsequent section that this is the same timeframe (1130Z) when the western eyewall is affecting mainland Puerto Rico, with much weaker sustained winds.

[part 3 in next post]
 
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Puerto Rican mainland:

“Satellite data and San Juan radar indicate that the west wall of the eye moved over land near the towns of Ceiba (Roosevelt Roads Naval Air Station), Fajardo, and Luquillo, while the east side of the eye remained over water.”

“…the anemometer site at Roosevelt Roads Naval Station is well exposed, and height of the propeller/vane anemometer is 7 m. The time history of recorded peak gusts, unadjusted for anemometer height [below], shows that peak gusts of 104 knots (120 mph) occurred between 1150 and 1220 GMT…and an almost complete penetration of the eyewall was observed at 1250 GMT.”

“…The 7-m anemometer at Roosevelt Roads is located adjacent to the main runway and has a clear exposure to wind from all directions.”


p200046c9g37002.jpg


“Maximum sustained winds at this site were approximately 85 knots (98 mph). Mechanical equipment and a part of the air operations building roof were lost at 1339 GMT, terminating wind-speed and direction recordings at Roosevelt Roads. Because the site satisfies the requirements for standard exposure, the only required adjustment to the data is for the height of the anemometer. This would have the effect of increasing the observed speeds by about 6 percent.”

The report concluded that the maximum sustained winds at Roosevelt Roads were lower (85 kt) from a complete review of the stripchart data, but also concluded that adjusting for the anemometer height resulted in maximum sustained winds of 90 kt, matching the NHC value (Category 2 intensity).

This same western eyewall (actually, the northwestern eyewall given the eliptical slant of the eyewall at this time), subsequently passes over Luquillo and just to the east of San Juan.

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1200Z best track:

center position 18.2N 65.5W , about halfway between Vieques
and SE tip of mainland Puerto Rico
pressure 945 mbar mbar
intensity 110 kt

At 1208Z, a recon vortex fix in the center of Hugo’s eye, located at 18.3 -65.5, or about 6 nmi to the east of Fajardo, measures a pressure that has risen to 955 mbar, and observes the eye is approximately elliptical, stretching 30 miles along an axis of 60 degrees (that is, an axis stretching from WSW to ENE), and 20 miles wide along the perpendicular axis. Also noted is that the eye is open to the SE. These are all signs of weakening and of the in-progress ERC. The recon also notes that the highest flight level winds encountered on the leg leading up to the center fix, which traveled into the eye from the south, were winds from the west at 67 kt (i.e, zippo).

“A storm chaser was able to position himself in a multistory condominium in Luquillo and produced a remarkable videotape of the approach and passage of Hugo's eye directly over head. The videotape documents damaging wind and rain effects on nearby structures during major rainband and eyewall passages in Hugo, as well as the chaotic state of the adjacent sea surface. He used a digital barometer to measure a lowest pressure (956 mb). San Juan, which remained outside the eye, recorded a minimum pressure of 970.3 mb. The radar sequence supports the pressure data indications that Hugo was filling as it crossed the northeast coast of Puerto Rico. However, it must be emphasized that the western eyewall passed just to the east of metropolitan San Juan, probably affecting Loiza and Pinones; moreover, this geometry is entirely consistent with the large gradations of damage and surge effects (especially overwash) documented by the team from Catano eastward.”

At 1238Z the same recon flight on its way north records the highest flight-level wind speed in the stronger northern eyewall: 108 kt. This translates to surface-level winds of 92 kt (using 85% reduction) – strong Cat 2 winds. This could also be considered the northwestern eyewall given the elliptical shape of the eyewall recorded minutes earlier. This maximum is located about 25 nmi to the NNE of Luquillo at this time.

At 1230Z, San Juan radar shows that Hugo's eye has partially filled.

1300Z fix: 18.30 -65.60 just offshore, 3 nmi SE of Fajardo

1330Z center passes just to the east of the northeast tip of Puerto Rico. San Juan radar shows that Hugo's eye has completely filled.

Highest winds at San Juan:

The record of sustained winds from San Juan airport indicates the close passage of the western eyewall as occurring between 1330Z and 1400Z; these highest sustained speeds of 65-67 kt are at the threshold for Cat 1 sustained winds:

1989 9 18 13 2 340 27.8
1989 9 18 13 20 350 26.8
1989 9 18 13 25 350 27.8
1989 9 18 13 32 350 28.8
1989 9 18 13 37 340 33.4
1989 9 18 13 45 350 34.0
1989 9 18 13 50 340 34.5
1989 9 18 14 15 320 29.3
1989 9 18 14 50 280 23.7


The highest gusts during this same timeframe are on the order of 80 kt, consistent with a ratio of 1.20 to 1.25:

1989 9 18 13 25 350 34.5
1989 9 18 13 32 350 39.6
1989 9 18 13 41 340 39.6
1989 9 18 13 46 350 40.1
1989 9 18 13 52 340 41.2
1989 9 18 14 15 320 41.2
1989 9 18 14 44 280 35.5


“The WSFO at San Juan recorded peak gusts of 80 knots (92 mph) between 1350 and 1415 GMT, and the maximum sustained wind speed was 67 knots (77 mph). Adjustment for the 6.1-m height of the F420 C anemometer would increase the plotted wind speed in by about 7 percent.”

And from a separate section on surface wind speeds:

“The WSFO at Luis Munoz Marin International Airport in San Juan recorded peak gusts of 80 knots (92 mph) between 1350 and 1415 GMT..The maximum sustained wind speed was 67 knots (77 mph). Adjusting this figure to take into account the 6.1-m height of the F420C anemometer would increase the maximum sustained wind speed by about 7 percent to 72 knots (83 mph).

“It is known from eyewitness accounts that the eye passed over the region from Luquillo east to Cape San Juan. Because the winds there would have been directly off the ocean, speeds slightly higher than those at Roosevelt Roads Naval Station may have been reached.”


The report concluded that maximum sustained winds at San Juan’s airport, which was just on the fringes of the western eyewall, were 72 kt (Category 1), and that maximum sustained winds at Luquillo may have been slightly higher than at Roosevelt Roads; that is, slightly higher than 90 kt.

Since the range of Cat 2 winds is 83-95 kt, only by an overly generous allowance beyond "slightly" would Luquillo have received sustained Cat 3 winds, but more likely received Cat 2 sustained winds and Cat 3 gusts, given the standard ratio for over water of 1.20 to 1.25, with gusts probably no higher than 115 kt.

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“Hugo's ill-defined eye moved north-northwest after hitting the northeast coast of Puerto Rico, and by noon on September 19 [sic; it was actually noon on the 18th] was over open water north of San Juan with maximum sustained winds of 109 knots (125 mph) and minimum sea-level central pressure (MSLP) of 957 mb.”

1400Z fix: 18.46 -65.76 offshore, 7 nmi NNW of Luquillo

At 1428Z another vortex fix at 18.55 -65.87, or about 5 nmi north of the Puerto Rico coast about halfway between San Juan and Luquillo, shows similar mslp as the earlier vortex, slightly higher, 957 mbar, and expansion of the elliptical eyewall to 40 and 30 nmi diamters, respectively, along an axis of 30 degrees (SSW to NNE), and indicates the eye is open to the south. It has found no stronger flight-level winds than 65 kt, and the previously measured 100 to 110 kt at 1235Z on the earlier fix.

1500Z fix: 18.62 -65.92 offshore, 11 nmi NNE of San Juan

1800Z best track:
center position 19.1N 66.4W, about 45 nmi north of central Puerto Rico
pressure 958 mbar mbar
intensity 105 kt

“The storm's radar structure, as documented by the 5-cm belly radar from the NOAA WP3D aircraft, is [below]. Note that the southeastern half of the storm is nearly devoid of rainbands.”

“a P-3 radar image from around 20Z on the 18th shows a much deteriorated eyewall structure with no rainbands remaining over the southeastern two thirds, and the remaining strong convection to the right of the forward movement”
[from about 350 to 015 degrees]

p200046c9g36001.jpg


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I am about to become very busy and this will likely be my last post for awhile...unless an amazing TC comes along that cannot go without notice.
 
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I will continue stand by my estimate of wind gusts of over 140kts in Luquillo P.R. during Hugo, Case Closed!!!! If you would read the report the damage survey indicated F-3 damage in St Croix and N/E Puerto Rico. Unless you were there you cannot dispute it. I have experienced over 50 hurricanes of all sizes and intensities except a category-5. The video on a 2 inch muddy screen does not tell the real story of the force of the wind, you have to be there. There was an exploding house that Mike and I caught on tape along with flying debris of all sizes and constant sound of glass breaking from all directions. Palm trees were reduced to stix. All windows in the condo facing the ocean were blown in to a point that the metal front doors to some apartments were blown out into the hallway. Windows on the lee side were blasted out frames and all. I have been in many hurricanes with 110mph winds and the damage is much lighter than in Puerto Rico. Mike has shown a still of a concrete two story house in front of our location with the second floor blown off.
Wind gust of 164mph was recorded at TPC during hurricane Andrew outside of the eyewall. Even though this was on top of a ten story bluilding the wind at tree top level was probably around 150mph. The tree damage in that area was nothing like the tree damage in N/E Puerto Rico.
This report of a gust to 120mph at Roosevelt Roads was on the southside of a decaying southern eyewall down wind of a Mountain range in eastern P.R.
 
Hi Margie - In an attempt at brevity, I am only responding to the most relevant points from your post...

“...Also of value in assessing the relative strength of Hugo and, hence, the intensity of surface winds, were estimates of central pressure and eye diameter presented in post-storm summaries prepared by the NHC (Lawrence, 1989)."
I have no challenge to this overall citation, other than "estimates of central pressure" in "summaries prepared by the NHC" is skewed with respect to the observed pressure at Luquillo...which was likely lower than documented.

“In the following paragraphs is an assessment of surface-wind speeds for each of the major areas affected by Hugo. Also included is a description of the reported speeds and the final disposition of these reports."
Again, no challenge. I am happy to stand firmly in contradiction to this particular report's final disposition on several points. And I have previously made numerous citations to the 1990 survey, which also stands in contrast to numerous conclusions from this report.

"In general, the most damaging winds were located in the northeast quadrant of the storm. This quadrant was also where the most intense rainbands, as indicated by their radar reflectivity, were located."
I am in agreement that the highest flight-level winds were located in the northeast quadrant. That said, the following portion of the report's statement -- "This quadrant was also where the most intense rainbands, as indicated by their radar reflectivity, were located" -- is absolutely not true for numerous instances during Hugo's lifecycle and particularly between the time it left St.Croix and when it crossed Puerto Rico. Even in the 17/23Z airborne radar image that you posted, there is a narrow strip of intense eyewall convection in the NE quadrant, but the most intense reflectivity in the eyewall is from the north through west quadrants, with the thickest portion of the eyewall squarely in the NW quadrant. The 700mb winds superimposed on that radar image, do indeed indicate a peak flight-level wind of 140kts due east of the center, in an area of practically no intense reflectivity...with another maxima of 135kts due north of the center right in the intense convection. My comments relating to this particular image: 1. The recon flight plan did not allow for sampling the winds over the NW eyewall, where the most intense reflectivity is located. 2. While it is likely that the flight-level winds in the NW eyewall probably were not as strong as those shown in the NE quadrant (140kts), I would firmly suspect that they DID mirror the values in the Northern eyewall (135kts)...and, because this is where the most intense convection is, more of the flight-level winds would have been brought down to the surface...probably yielding higher surface winds, especially in gusts, in this area... probably even higher than what was occuring over the Eastern eyewall, where flight-level winds were slightly stronger, but there was no appreciable convection

Probable Maximum Wind Speeds
Location................Max Sust Wind (kt)..Gust (kt)
---------------------- ------------------ ------------
Virgin Islands:
St. Croix...............110.................135....... ......(Cat 3)
St. Thomas...............85.................105....... ......(Cat 2)

Puerto Rico:
Culebra.................105.................130... ..........(Cat 3)
Vieques..................95.................115... ..........(strong Cat 2)
Roosevelt Roads..........85.*..(90).........104.*..(110).... (Cat 2)
San Juan Int’l Airport...67.*..(72)..........80.*...(86).....(Cat 1)
I strongly disagree with virtually every one of the windspeed estimates shown in the the referenced table...both sustained and gusts. Even with actual observation at Roosevelt Roads, where I agree with the observed value accurately representing the windspeeds in the Ceiba/Roosevelt Roads NAS area, I do not agree with the report's assessment that the observation platform sufficiently represents a "standard exposure" or that the anemometer is "well exposed". It is... in terms of it's immediate surroundings... but, particularly in light of the direction of Hugo's strongest winds in this area (over land from NNW to NW) and with a 3,500ft elevation only 5 miles distant...and in the direction that the strongest winds would be coming from... I am quite confident that surface winds in the area of Ceiba and Roosevelt Roads were reduced, wholesale, by around 15-17%... from what they would have been from an onshore, non-blocked vantage point in the western eyewall.

From my perspective the Roosevelt Roads values listed in this table cannot be used, without additional adjustment, to accurately reflect valid windspeeds in other areas affected by the eyewall over NE Puerto Rico. Additionally, as far as the remaining estimates...they are just that, estimates. And, owing to the primary methodology for determining surface winds in this this report, (i.e. applying a standard reduction to observed flight level winds), in my opinion are overly, if not excessively, conservative...likely by 10-20kts.

The report found the damage consistent with these windspeeds.
The report actually states, "Observed damage in the areas affected by Hurricane Hugo is in general agreement with the surface-wind speeds listed." There is a lot of generalization in that "general agreement" comment. And, again, if the game is to simply cite the perspective of an independant damage survey, the 1990 DOC-NOAA damage assesment yielded upper F1-F2 damage, with localized areas of possible F3 damage (attributable to microbursts or other orographic effects) with peak winds estimated at 161mph across the most severely impacted areas, including: St.Croix, Vieques, Culebra, Fajardo and Luquillo.

In conclusion, there is no evidence of sustained Cat 3 winds on the Puerto Rican mainland, either from direct ground measurements or recon data or by a very thorough post-analysis. In order to claim otherwise you would have to be rejecting, wholesale, all the ground measurements, recon obs, radar obs from San Juan, and a detailed engineering assessment of wind damage. That is not logical.
Really? No evidence to whom? My own personal observations, as well as those of four other very experienced chasers, along with 25 years of field interceptions affords me a very unique perspective on Hugo's impacts to Puerto Rico. I am certainly not rejecting... all the ground measurements (all two of them...both compromised in some way); the recon obs (which did not consistently sample the NW eyewall); radar obs from San Juan (which do show that the highest reflectivity frequently WAS in the NW quadrant); or a detailed engineering assessment of wind damage (which is no more or less credible than the damage assesment from the 1990 survey, which had different findings).

I would challenge that if there is any "wholesale rejection" of data, it is your disregard for the 1990 survey findings and, more importantly, the qualified first-hand experience and testimony of myself and four other chasers, who actually were there. Furthermore, what is "not logical" is to assume that the data in ANY of these reports is completely static and cannot be argued and/or revised. If that were the case, there would be no need for the HRD forensic re-analysis effort that has been going on for years and has made hundreds, if not thousands, of changes to prior best-track positions and intensities.

<<continued>>
 
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<<continued>>

There is a suggestion that sustained winds slightly higher than 90 kt could have occured at Luquillo. Slightly could be bent to go so far as 96 kt, although that would be pushing it. Nevertheless, let's suppose that to be a reasonable, although unlikely possibility. That just puts you at the absolute threshold of Cat 3 sustained winds. There is no way that sustained Cat 4 winds can be construed from such a situation.
Wow... sustained winds of 96kts in Luquillo, I guess I should thank you for your generosity in allowing for that much? Even if we do suppose your "reasonable, although unlikely" 96kt value is valid, it is based on a derivation from the already flawed perspective of the (85)90kt record at Roosevelt Roads. I am curious, assuming again that we put aside the small fact that I actually witnessed it first-hand, and that your expert opinion on Hugo's intensity in Luquillo (from snowbound Minnesota) is true... what is your perspective and wind estimates for the numerous other recent videos showing high winds events.


What would you estimate the sustained/peak winds in this video from Mike Theiss, during the eyewall of Hurricane Charley in Charlotte Harbor?http://www.ultimatechase.com/Video_Library/Hurricanes/Hurricane_Charley_Gas_Station_Stream.htm

What about this clip from Jim Edds, also during Charley in Punta Gorda?http://www.extremestorms.com/charley.wmv

What about my video from Belle Meade in Hurricane Wilma?
http://www.tropmet.com/images/gallery video/mpeg/Hurricane_Wilma_3_320_512kbs.wmv

...or my video from Key West during Hurricane Rita?
http://www.tropmet.com/images/gallery video/mpeg/Hurricane_Rita_7_320_512kbps.wmv

I really am curious and would like to hear your personal estimates of sustained and peak winds in each instance.

Your video was a good video, without the hyperbole. Why do the winds you videotaped at Luquillo "have to be" Cat 4 sustained winds when it is simply not a possibility?
Thank you for the compliment on the video. The short answer to your question is, because it is the truth. What I infer from your comment "[My] video was a good video...why do the winds..'have to be' Cat 4"...is that you appear to believe I am either interested in somehow inflating the appeal of the video, or that my pride as a storm-chaser would be somehow bruised. Neither could be farther from the truth and if you think otherwise, then you have missed the point entirely. I'll also remind you that you are the one who started this debate...and accused me, rather publicly, of hubris! I am just responding to what ultimately are your personal perspectives and citations from other people's work and documents, as they relate to my video. Now...just as you have asked me, I also ask, why is it so important for you to discredit my estimates of what I personally experienced and videotaped in Luquillo?


Your comment that category four winds at Luquillo are "...simply not a possibility", just reiterates that you are not willing to accept anything other than what is "officially" documented, and even then only what fits your argument. I am fully willing to respect the perspectives of ALL of these documents and also accept that you personally do not believe that category four conditions impacted Luquillo. But, to assert that there isn't even a "possibility" is tantamount to saying that I don't know what I'm talking about; that I haven't spent the last 18 years evaluating and re-evaluating my own (as well as others) footage from Hugo to refine my estimates; and that I have basically overestimated wind speeds by 20kts, or more, for every storm I have intercepted over the last two and a half decades.

Even though you claim to have approached the subject of this debate from an "open-minded" and evaluative perspective, you have been more than willing to discount my personal observations and estimates, and those of other experienced chasers, who were actually in Hugo...presumably for lack of empirical data. That said, you were more than ready, in your original post, to provide your own expert analysis and wind estimates... 18 years later, watching a highly-compressed and pixelated video on YouTube.
 
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Hi all -- just a quick update that I received feedback from Dr. Golden, regards asking him about the ambiguity in the 1990 Hugo report, and whether or not it was superseded by the 1994 report. He replied, "I stand by my report for the NAS/NRC team in 1994; you should use our report and the NHC post-season report." And these were the sources for information contained in my last posts (along with recon data and NOAA IR imagery), as I assumed the more-in-depth 1994 report superseded the earlier one.

Michael has explained to me that he believes he experienced 115 kt winds at Luquillo, not 90 kt, and does disagree with the results of the 1994 NAS/NRC report and the NHC post-season report on Hugo mentioned above. In turn, I let Michael know that if he had had a statement with the You Tube video description stating that his conclusions were different from the official assessments, I would not have had an issue with the description of the video.

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This continues to be an interesting topic, as the damage issue ties to a recent talk from the 2006 AMS conference (on Hurricanes and Tropical Meteorology) on collapsing precipitation cores in open-eyewall hurricanes such as Hugo. An extended abstract is provided as well that graphically illustrates the process using radar imagery from Ivan at landfall in Baldwin County, AL. I found this facinating...as if the eyewall's ongoing effort to rebuild constituted a last hurrah. These collapsing cores can produce extreme wind damage. The 1994 report on Hugo documented a string of microburst damage associated with the eyewall passage along the path towards Puerto Rico, including severe damage on the islands of St. Croix and Vieques. The report concluded that the worst damage was, in fact, due to microbursts, and not simply sustained winds.

This may also be of interest -- there is a personal account on WeatherMatrix, I believe, from someone who lived in Puerto Rico and experienced a lot of tree damage on their property due to microbursts associated with Hugo. Sorry I don't have the link.
 
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Michael.
It is quite obvious to me that this person will go to great lengths to discredit your Hugo report. She has even had to contact Joe Golden to try disputing what all of us witnessed. You have taken the time and energy to explain in every detail of what occurred that day. This discussion in my estimation will go on forever because this person will never be convinced that the winds in Luquillo Puerto Rico were more than 90kts.
 
Hello to all...

This is my first post on this forum and I've been reading very closely this debate about the intensity of hurricane Hugo when it hit Puerto Rico. First, I experienced hurricane Hugo in the town of Gurabo which is about 20 miles south of San Juan in an interior valley which is mostly open to the sea towards the east. Hurricane Hugo was my very first hurricane experience and also for people like my parents and it was a very impressive experience. We never got the max. winds of the storm but we were certainly at the core of hurricane intensity winds for many hours with the worst conditions being experienced at around 10am when the eye was just to our NE passing over the Luquillo- Rio Grande area. My personal estimates based on other hurricane experiences and pictures is that the Gurabo area experienced peak sustained winds or around 90-105mph with gusts probably as high as 120mph.

I remember going to the NE tip of the island after Hugo and the sight was that of a nuclear bomb attack, at least that was the impression for a kid of my age at that time. When the years passed and I started to study hurricanes more in detail (specially after the 1995 season which was very active for us in the NE Caribbean) I got more interested in re-evaluating Hugo's intensity. This was mainly because I consistently heard from weather reporters here that Hugo was a category 2 hurricane in Puerto Rico, some even said that it was a category 1 storm. That didn't sound logical to me. Specially when I read the wind reports of Roosevelt Roads and the pictures of the Naval Station after the storm didn't match to me. The wind damage there to buildings in more exposed areas and vegetation was a lot similar to that of St. Croix. Also the videos and pictures of during and after the storm in San Juan did not match with the report of 77mph winds and peak gust of 92mph. Some pictures of Parque del Indio in Condado on the Beach showed every palm tree without fronds and damage in the Hato Rey area inland in San Juan was too strong to what one would expect from a category 1 intensity hurricane. With this in mind, lets get into the debate.

Margie Kieper said:

<<My first thought on viewing the video was that the top windspeeds appeared to be around 100-110 mph (about equivalent to 90-95 kt) -- a strong Cat 2, based on the size of flying debris that was seen, and the condition of the palms after the high winds had passed (the majority were not denuded). I also observed the winds were mainly being filmed as they funneled between two high-rises (Bernoulli effect).>>

The theory of a Bernoulli effect in the video is highly incorrect, I have two, two hours-long videos of hurricane Hugo (the same ones you saw much shorter in the small pixeled You Tube video) and there is only one portion of the video in which they take scenes between the two buildings and that was before they got the peak winds. There are only two condos in that area which were the Sandy Hills (unless I do not know the area enough which I highly doubt because I've been there many, many times) in which they were and the video was taken facing generally west as Richard Horodner pointed out, this was facing towards the Costa Azul area were there were no condos near as I expressed before. So, with all due respect, your Bernoulli effect argument on this video is incorrect.

<<My second thought was that someone who lives in a coastal high-rise in an area vulnerable to hurricanes was going to watch this video, read the information provided about the video, and conclude that not only would it not be necessary to evacuate any major hurricane (Cat 3-4-5) bearing down on them, since the high-rise in the video remained intact during "Cat 4" winds, but that it might be a fine and dandy thing to sit and watch it right out their window.>>

Where you expecting the condo to collapse? I mean, this has been discussed a lot in this debate and it seems extremely clear that even windows on the lee side of both Sandy Hills were ripped of the buildings not to mention the apartments facing towards the ocean, that has to give any person an idea of what would be the hazards of bearing a major hurricane in a condo.



<<As already mentioned Hugo was not a Cat 4 at landfall in Puerto Rico, but a Cat 3. Peak windspeeds were determined to be 127 mph (110 kt), but likely remained offshore. The highest sustained winds measured on land in Puerto Rico were Cat 2.>>

Have you made at least a little geographical analysis of the area of the measurement? The location of Roosevelt Roads is in Ceiba, the extreme eastern tip of Puerto Rico, it has el Yunque Montain Range to its West, it has 200-300 ft mountains to its north and a 250 ft hill to the ESE of the runway. It has the 3600 ft El Yunque Peak just to the west around 8 miles and less than 5 miles to the west of the runway is a 1050 ft peak just by reading the aeronautical charts. If you can make an imaginary map of what I just showed, the place is not as "exposed" as you try to make it look like. In fact you'll be interested to read the following information:

Winds measured in Roosevelt Roads during hurricanes Hugo and Georges:

Hurricane Hugo:

90 kts G104 kts from the W

Hurricane Georges:

78 kts G93 kts from 150 degrees or SE

The interesting thing with this report is that as the NHC Preliminary report on hurricane Georges says:

"One of the most important observations reported was in Fajardo, Puerto Rico where the Civil Defense office measured a sustained wind of 96 knots with gusts to 113 knots at 2130 UTC 21 September. Operationally, this report was the basis of making Georges a category 3 hurricane at landfall in Puerto Rico."

Fajardo which was further north reported higher winds. Then Mrs. Kieper can you tell where the logic of all of this goes? This is very simple, the report out of Fajardo was from a more exposed location than that of Ceiba which one would expect had to report similar if not stronger winds during hurricane Georges as they got the NE eyewall which had a stronger signature on the Cayey Radar. Also it was interesting for me to see that the rate of under-estimation for that station for both storms was similar in comparison to the actual intensities that Ceiba might have seen on both hurricanes.

This is assuming Hugo's sustained winds were of 130mph in Ceiba if it were in an unexposed location we get 130-105 = 25 mph lower than winds in the same town at unexposed sites. With hurricane Georges we get 115-90 = 25 mph lower than winds in the same place with at unexposed sites. Even though the wind directions on Hugo and Georges were different for that place, in both times the instrument was blocked by terrain. Also consider that Ceiba was more in the W (and later S) eyewall of Hugo and Rio Grande, Luquillo and Fajardo got more of the N and NW eyewall of the storm by the angle it approached the area. Also notice that the peak winds in Georges were blocked to the anemometer by the afford mentioned 250ft hill ESE of the runway. There is blockage almost everywhere around that runway, you even can see it from highway 53 which lies at a higher altitude west of the base and there are many high trees and forests and mangroves around which further add to the friction problem. So do I have to say more about the quality of the measurement in Roosevelt Roads? Case closed with this one as Jim Leonard says.

continued>>>
 
>>>cont

<<Also of note is that the minimum pressure at Roosevelt Roads was 946.1 mbar, and occured at 1250Z. The minimum pressure at Luquillo was 956 mbar, noticeably higher, and that occured ten minutes later at 1300Z.>>

The minimal pressure reported in Ceiba of 946mb vs. 956mb in Luquillo can't be compared as it has been stated by the chasers which were the ones who took the measurement that they read that pressure on the barometer much after half the calm during the eye and that at that point the pressure was rapidly rising. So a lower pressure in Luquillo, likely close to the one measured in Ceiba seems very plausible. If not, then we had and "explosively" weakening storm!

<< Do you see the trend? Pressure increasing at every track point, and vmax falling with every track point? Take a look at the mslp-vs-time and vmax-vs-time graphs from the Hugo best track. Hugo weakened for 48 straight hours, from 18/00Z to 20/00Z then strengthened from 20/00Z to 22/00Z, prior to landfall in South Carolina.>>

This example you are trying to use shows that even though you've shown knowledge on TC's (specially coming from a place which doesn't see hurricanes and which is admirable), you still are a long way (as most of us) from understanding many things in regard to the wind/pressure relationship in tropical cyclones. I would like to show you the example of a storm of similar intensity than that of Hugo. It is hurricane Michelle in November 2001. This storm really made me curious about how the winds and pressure in hurricanes relate, then talking with Jim Leonard so many times we've seen that the changes in wind intensity are not as fast as pressure changes. Then a storm with a rapidly falling pressure will have its winds increasing at a rate lower than that of the falling pressure. This has been the case many times and it also happens with rising pressure, in Hugo the pressure was rising in the hours prior to landfall in Puerto Rico, also the satellite signature of the storm did indeed deteriorate compared to 6 hours prior to landfall, but the intensity of the storm was pretty much the same in Puerto Rico than when it passed over St. Croix and this is clearly reflected in the similar damage in the afford mentioned places.

Then why I mention the Michelle example?

Based on the "best track" of hurricane Michelle on NHC's preliminary report:

Michelle's winds increased to a first peak of 115kts with a pressure of 937mb at 03/1200 then the winds leveled off to 110kts and the pressure was actually lower at 934mb at 03/1800. The listed lowest pressure is of 933mb at 03/2100 with 110kts winds. Thereafter the pressure rose constantly until the end of the storm's lifecycle. When the pressure was 11mb higher at 04/0600 the winds were 10 kts higher also at 120kts. I also have to mention that the storm's structure was deteriorating as it approached Cuba until landfall at Cayo Largo (04/1800) but the winds remained at 120kts and the pressure was 16mb higher than at the lowest point !
"Do you see the trend?"
In Hugo similar things happened, the pressure was rising and the satellite presentation was not as good as 6 hours earlier but the winds were still there clearly present with all the evidence of damage and videos. Then the lowering in the winds was evidenced after it moved over Puerto Rico thus supporting the similar wind damage experienced in St. Croix, Vieques, Culebra, Fajardo, Luquillo and Rio Grande and thus showing similar, sustained category 4 hurricane strength winds on these areas.

Based on all of this I estimate Hugo's 1-min winds to be on the 115-120kts range when it hit the NE of Puerto Rico, Culebra and Vieques. The damage by the storm was the worst from Humacao to Rio Grande along the coast and Vieques-Culebra and there are areas of Fajardo, Luquillo and Rio Grande in which the damage looks similar to that done by typhoon Paka in 1997 in Guam. Also going to the San Juan Metro Area there is an unofficial wind gust report of 110mph in Guaynabo around 10 miles WSW of the International Aiport in Carolina. The unexposure of the instruments at the airport were very nicely explained by Richard Horodner and I only want to add that the same problem was experienced during hurricane Georges in 1998.

The airport at SJU reported a max sustained wind of 79mph from the NE with a peak gust of 93mph. The rate of under estimation was also similar to that of what the city saw with hurricane Hugo. The damage in San Juan was similar but a little less intense than on hurricane Hugo so winds of 100mph sustained or maybe more might have been experienced on the city during Georges, again showing the discrepancy between the measurement and the damage experienced.

Mrs. Kieper if you have seen damage done by major hurricanes on tropical areas of the World you would rapidly recognize that the damage done by hurricane Hugo on these areas was that of a major hurricane very likely of category 4 intensity. Even the damage done by category 3 hurricane Georges here in 1998 in the same places (and with actual measurements of cat-3 intensity, Fajardo) were less severe to that of Hugo. Places like Luquillo Beach and close to there, "Los Kioskos" in road #3 which on that part was flooded after Hugo, the damage on the vegetation on the same place compared with pictures and videos after both storms did look less severe after Georges than after Hugo. There is every reason in the world to think Hugo was stronger than Georges here, and that it was a category 4 hurricane.

Jose
 
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