Margie Kieper
EF1
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:
"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.
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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