2004-09-03 FCST: Ivan (Atlantic)

[Jeff Snyder]

Originally posted by Glen Romine+--><div class='quotetop'>QUOTE(Glen Romine)</div>

<!--QuoteBegin-Tim Vasquez

These graphs from Caymans are quite interesting... looks like anemometer broke at 90 mph:
http://www.weatherincayman.com/currcndx.htm

Tim

so I'm not sure about any of these measurements when combined with the obviously faulty rain rates.

Glen[/b]

Aww, you mean it's not likely to have 97 in/hour rain-rate (which was the recorded 'high')? I'm assuming the sensor got taken out by something (or just blew off) since it is solar-powered... I was hoping this would be able to withstand the wrath of Ivan, as it'd be very interesting see how fast the pressure drops as the eye got close.

It's quite rare to see so much "gray" on the NOAA SSD infrared satellite imagery (gray = very cold cloud tops). Convection is currently weakening a bit in the northern semicircle, but that's like a diurnal fluctuation and perhaps a byproduct of an eyewall replacement cycle. The eye looks a little ragged and motion a little wobbly, so we'll see if the eye collapses for a time as has been the case with previous replacement cycles... The forward speed certainly has slowed, however.

 

[MClarkson]

the site reported a rainfall rate of "15.16 in/hr" over a 5 hour period without changing.

seems it has failed in some manner.

 

[Glen Romine]

I suppose the instrument may have become submerged. According the climatology summary link off the page, the site elevation is only 4 feet.

http://www.weatherincayman.com/NOAAYR.TXT

Glen

 

[Tim Vasquez]

Also, before anyone jumps to any conclusions about why the Cayman server is up, VisualRoute shows it is based in Santa Monica CA, so the weather station likely FTP'ed its data until it lost power or communications.

Tim

 

[David Schuttler]

Originally posted by Glen Romine
I suppose the instrument may have become submerged. According the climatology summary link off the page, the site elevation is only 4 feet.

http://www.weatherincayman.com/NOAAYR.TXT

Glen

Could be
From Caymen Net News

As predicted, widespread flooding from the expected tidal surge was affecting a large part of the island. One report of a house standing eight feet above normal sea level had water ankle-deep inside. In lower-lying areas there have been reports of people having to climb onto kitchen counters to escape the seas that came flooding into their houses[/url]

http://www.caymannetnews.com/2004/09/738/damage.shtml

 

[Austin Ivey]

Interesting forecast discussion from New Orleans this morning. Kinda long but worth the read:

"IT WILL BE INTERESTING TO SEE IF IVAN STARTS TO MAKE THAT LONG EXPECTED TURN TO THE NORTHWEST TODAY THAT THE MODELS HAVE BEEN CONSISTENTLY SHOWING BUT SO FAR NOT VERIFYING. WATER VAPOR IMAGERY AND RECURVATURE TECHNIQUES FROM SATELLITE SUGGEST IVAN SHOULD START NTERACTING WITH A WEAKNESS IN THE RIDGE TODAY...CAUSED BY A WELL DEFINED SHORTWAVE TROUGH MOVING EAST-SOUTHEAST INTO THE LOWER MS VALLEY. THE PROBLEM
IS THIS INTERACTION MIGHT ONLY BE TEMPORARY... THUS ALLOWING THE MID/UPPER RIDGE TO REBUILD SLIGHTLY AND TURN IVAN
BACK WEST-NORTHWEST. ANOTHER CONCERN IS HISTORICAL TRACKS OF CATEGORY 4 AND 5 HURRICANES IN SEPTEMBER IN THE NORTHWEST CARRIBEAN SEA ARE MOSTLY WEST-NORTHWEST ACROSS YUCATAN...THEN MAINLAND MEXICO...LIKE GILBERT. LARGER STORMS TEND TO CREATE THEIR OWN ENVIRONMENT AND HAVE LESS INFLUENCE FROM SURROUNDING FEATURES. HOWEVER...AS WE HAVE SEEN THE LAST SEVERAL YEARS...THERE HAVE BEEN NUMEROUS STORMS THAT HAVE GONE AGAINST CLIMATOLOGY...SO THERE WILL BE A LOT OF UNCERTAINTY ON THE TRACK AND FUTURE STRENGTH OF IVAN.
MODEL TRENDS CONTINUE TO TAKE IVAN A BIT FARTHER WEST WITH EACH MODEL RUN...BUT MOST ARE WELL CLUSTERED NOW AND SUGGESTING A U.S. LANDFALL NEAR PANAMA CITY FL WEDNESDAY AFTERNOON. THE BREAK IN THE UPPER RIDGE JUST TO OUR EAST AND THE SOUTHWEST UPPER LEVEL WINDS TO THE EAST OF THE TROUGH AXIS SHOULD CAUSE IVAN TO TURN NORTH AND POSSIBLY NORTH-NORTHEAST AS HE NEARS THE NORTH GULF COAST. IT IS STRONGLY ADVISED THAT EVERYONE WATCH FUTURE DEVELOPMENTS OF THIS
HURRICANE. "



Will be interesting to see if Ivan has created his own environment to the extent that upper air features don't have as large an influence as forecasted by the models....thereby potentially moving US landfall west.

 

[David Wolfson]

The storm is still tracking quite persistently west of the adjusted progs. I still don't see much indication of influences that would turn it significantly at its current latitude. I'd say it looks to clip the tip of Yucatan and then continue to bend north toward Mobile, give or take New Orleans and Tallahassee.

 

[Kevin Scharfenberg]

Well, the 12Z guidance has indeed shifted left, again. The GFDL brings Ivan ashore near Pensacola Thursday at 06Z, the UKMET is near Mobile Bay at the same time, and the GFS is near Panama City at the same hour. FWIW, the eta model shows the storm near the mouth of the Mississippi at 00Z Thursday.

 

[Glen Romine]

Ivan appears to be entraining quite a bit of dry air today from the NW side of the strom as it presses into the upper high most recently centered over the western tip of Cuba. Earlier this week an upper low leading Ivan was helping to pump deep moisture in advance of the system, but that help is now gone, and the effects of the drier air wrapping into the storm appear to be taking effect now. Expect the next recon will find a continueing filling of the storm. Eventually, either the high will have to budge, or Ivan will have to traverse around it for Ivan to start a northward track. To me, I think Cuba will be spared and Ivan will continue WNW for another day, then curve up between Cuba and the Yucatan. Then, the expected curvature could start to kick in leading to a landfall back around Pensacola. Not very scientific - but heh, it could happen.....

Glen

 

[Jeff Snyder]

Originally posted by David Wolfson
The storm is still tracking quite persistently west of the adjusted progs. I still don't see much indication of influences that would turn it significantly at its current latitude. I'd say it looks to clip the tip of Yucatan and then continue to bend north toward Mobile, give or take New Orleans and Tallahassee.

FWIW, the 12z CMC (Canadian) model now brings Ivan near GALVESTON, TX! The CMC has been the western outlier, but even my preferred models (NOGAPS and UKMET) have been, usually, west of the NHC official track.

 

[Glenn Rivers]

A thought about the 80 inches/hour…not that I am convinced that it is accurate, but in the Rosenfield Z/R relation that would correlate to a reflectivity of 64 DBZ. That would usually be colored very dark red on WSR-88 graphics. Usually I think that most radar meteorologists like to put a hail cap at 55 DBZ regardless of the Z/R being used, but it is hard to picture a situation were hail would reach the ground in the inner core of any hurricane.

 

[Glenn Rivers]

The NHC people are expecting Ivan to be a Category 3 during most of its time in the Gulf. Other than the wind shear, I think a critical factor is going to be the mid level relative humidity. During the 48-96 hour period in today’s GFS, the 500 Mb humidity is very high outside the storm over the NE part of the Gulf Coast, but in TX and LA there is a pocket of 500 Mb RH as low as 20 % outside the storm. I wonder if this means that a further W track across the gulf will cause problems with entrainment of dry air, while a further E track closer to FL could allow the lack of dry entrainment to help make up for any shear and keep Ivan very strong. Any thoughts on this?

 

[Glen Romine]

Originally posted by Glen Romine
Expect the next recon will find a continuing filling of the storm.
Glen

Sigh, well, Ivan is getting he last laugh apparently, as the storm still has a low central pressure following a day long eyewall contraction (it shows up nicely in an IR animation). Interestingly though, winds have not been found to be that strong today by Recon (~ 130 knots at flight level) - despite the low pressure. The coldest cloud tops are also clearly assymetric, and such assymetry is not typical for such a strong storm. Will be interested to see if the winds stay low in the next recon report.

Glen

 

[MClarkson]

MAX FL WIND 155 KT NW QUAD 2339Z.

 

[Zach Bailey]

3z advisory is out and Ivan is back up to category 5. Recon found FL winds of 155kt and the pressure has dropped back down to 916mb. As suspected, track guidance has shifted further westward with Ivan now barely crossing over cuba.

Since Ivan is a large enough force to create and manipulate the weather patterns around him, I think that he will make it to the gulf as a cat 4 and stay that way until landfall around mobile or maybe a little east of mobile.

I'm not extremely worried about the cooler waters since upper level flow is supposed to be changing in Ivan's favor soon.

What does everyone else think?