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Wednesday, August 24, 2005 |
AT 5 PM EDT...2100Z...A TROPICAL STORM WARNING AND A HURRICANE At 5 PM EDT, the center of Tropical Storm Katrina was at 25.6 North 77.2 West, 185 miles southeast of the east coast of Florida and moving to the northwest at 9 mph. Maximum sustained winds are 45 mph and minimum central pressure is 1002 millibars (29.59"). Initial intensity was set based on a combination of recon observations and satellite image analysis. There is uncertainty over the exact position of the center and the direction in which it is moving. Position given is a combination of recon, satellite, and radar observations. Other than that the short term forecast is fairly certain. Katrina will run into the southern edge of an upper level ridge of high pressure and be turned to the west. This will take her over south Florida in the next 36-48 hours. After that there is greater uncertainty as the models are split over Katrina's course in the Gulf of Mexico. The track forecast is similar to that of the consensus of the global models. Steady intensification is expected before the first landfall, with Katrina doing so as a category one hurricane (intensity forecast also has Katrina as a category one on second landfall). However, rapid intensification is a possibility, although dry air wrapping into the center is acting as an inhibiting factor. Due to the slow forward speed, the main threat from Katrina will be heavy rain and flooding across the Bahamas and south Florida. Katrina has been giving mixed signals today. Pressure fell by four millibars or so, but there hasn't been much of an increase in the wind speeds observed by the recon plane. Here's the model guidance NHC had to work with for this forecast. NHC's forecast is along the lines of that indicated by the track labelled 'CONU', which as mentioned above, is a consensus of the global computer models. The GFS model continues to feature a sharper turn to the north and east. This may be skewing the consensus too far east. We'll have to watch and see how it reacts to the observations from the upper-air flight (which will be incorporated into the model runs tonight that will assist the 5 AM forecast tomorrow). I continue to be concerned about a significant hurricane (stronger than that currently forecast by NHC) affecting the area between Mobile and St. Marks by early next week. Residents in those areas should be thinking about preparations for that possibility. 2005 Hurricane Season, Weather comment []5:45:32 PM  trackback []
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AT 11 AM EDT...1500Z...A TROPICAL STORM WARNING AND A HURRICANE All data indicate that the depression has become much better organized this morning and is now a tropical storm. The intensity estimate is based off observations from the recon plane and is in line with estimates derived from satellite imagery. Forecast track is unchanged from previous advisories. The storm is expected to turn to the west after 24 hours and emerge in the Gulf of Mexico in 72 hours. The ridge of high pressure that is expected to cause the turn to the west is then expected to weaken, allowing northward motion to resume. With Katrina showing good organization and enjoying favorable atmosopheric conditions, Katrina is forecast to become a minimal hurricane by time of landfall in south Florida. --------------------------------------------------------------------------------------------------- The season continues its streak of earliest named storms. The previous earliest eleventh named storm on record was Karen of 1995, which formed on August 28th. The earliest 12th named storm also formed on that date. While there exists a tropical wave that has the potential to continue the streak, dry air continues to keep it in check, so it looks like the streak will come to an end. For south Florida there is not much new here. Everything is progressing as expected, with a strong tropical storm or a minimal hurricane expected to cross the peninsula on Friday. Shear being generated by the upper level high over the southeast should keep Katrina in that intensity range as she approaches the Florida coast. Of greater concern is the threat that Katrina could pose to the Gulf coast. The degree of the threat increases with the westward component of movement that the storm has. If Katrina turns west relatively soon, she will enjoy a short time over land followed by a fairly long time over the Gulf of Mexico. Favorable conditions would allow it to intensify rather rapidly. Alternatively, if the turn occurs later than forecast, Katrina suffers by being over land longer and gets less time in the Gulf of Mexico. It is a bit soon to rate the probabilities of the scenarios, however, it is worthwhile for residents of the Gulf coast from Mobile, Alabama to St Mark's, Florida to be aware of the possibility of a singficant hurricane affecting their area in six days. This is the computer model guidance the forecasters had to work with. The one significant outlier in earlier forecasts, the GFS (labeled AEMI in this graphic), has come more in line with the other models. As mentioned yesterday, the NOAA Gulfstream IV jet will be flying today to assist the computer models in their forecasts this evening (since the global models do not start calculating their forecasts until 11 PM or so EDT, any necessary changes to the NHC forecast would not be made until the 5 AM advisory package). Unfortunately, I am experiencing problems with my primary computer, hence the late update. Am working on a backup, but at the moment, my timeliness in updates is by no means a guarantee. Check with the National Hurricane Center for the latest and greatest on Katrina. 2005 Hurricane Season, Weather comment []12:52:13 PM trackback []
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© Copyright
2005
Charles Fenwick
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Last update: 9/15/2005; 9:46:41 AM .
Last update: 9/15/2005; 9:46:41 AM .
