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Wednesday, September 01, 2004 |
| At 11 PM EDT, a hurricane watch is up from Florida City to Flagler Beach, meaning that hurricane conditions are possible in the watch area within the next 36 hours. Frances is 60 miles east-northeast of the southeast Bahamas and 585 miles east-southeast of Palm Beach. Forward motion is still 14mph to the west-northwest, winds are still at 140 mph, and minimum central pressure has blipped up to 939 millibars. The forecast track is unchanged. However, the forecaster on duty has kept close track of the data for the ridge that is currently keeping Frances moving more to the west than north and has noted which models have handled it correctly (as well which have not) and anticipates that the 00Z model runs which will be part of the basis for the next forecast will give Frances more of a westward track. He also hints that there may be a bit of intensification in store for the hurricane. Weather comment []11:02:53 PM  trackback []
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| While I wait for the 00Z model runs to come in, I stroll around the blogosphere.
Weather comment []10:22:24 PM trackback []
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| Wind speed and pressure unchanged. Forward motion is down to 14 mph, moving to the west-northwest. It is now 40 miles north-northeast of Grand Caicos Island and 625 miles east southeast of the Florida coast. While the forward motion is expected to decrease, people should plan like it is not going to slow down. That would mean having all preparations complete by about noon on Friday (remember that hurricane force winds extend outward 85 miles from the center, so there will be strong winds a few hours before landfall occurs). Something I forgot to note in my previous post (probably of interest only to weather junkies). Upper air observations are usually taken only twice a day (at 0000Z and 1200Z / 8 AM and PM EDT) To try to help the models get a better grip on the critical high pressure ridge (and to assist forecasters in their own analyses) upper air observations are being taken every six hours at stations in Florida. University of Wyoming has a good page of atmospheric soundings as does the University Corporation for Atmospheric Research. For what's it worth this evening's soundings for Tallahassee and Jacksonville show an approximate 20 meter drop in 500 mb height from the 18Z sounding (potentially indicating that the ridge is weakening, which would enable a turn to the northwest and north for Frances). Weather comment []9:45:23 PM trackback []
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| Florida started to take notice of Florida today. I'll put my storm update and discussion first, with some news links at the end. At 5PM EDT, category four hurricane Frances was 35 miles north of Grand Turk Island and 650 miles east south-east of the Florida coast. It is moving to the west northwest at 15 mph. Winds are at 140 mph and the minimum central pressure is 938 millibars (27.70"). The National Hurricane Center forecast puts the storm in the immediate vicinity of Melbourne on Saturday afternoon with the storm proceeding northwest into Georgia on Sunday. When reading my discussion of the forecast track, please, please, please, keep in mind that a hurricane is not a dot. It is a very large system. For Frances, hurricane force winds extend out 85 miles from the center (For Charley, they only extended out 30 miles at the time of landfall) and tropical storm force winds extend 185 miles from the center. Also, it is better to be prepared for a storm that happens to turn away, then be unprepared for one that turns your way. In that spirit, I continue to advise everyone from the Florida Keys to the Carolinas to keep a close eye on the storm. There is currently a split in the lines of thinking among the forecast models. One set of tracks result from the high pressure ridge weakening. This causes the storm to virtually stall just off the coast of Florida, before proceeding northward to South Carolina on Monday. The problem is that the models making that prediction have consistently underestimated the strength and duration of the ridge, therefore that forecast is suspect (although, the forecaster on duty for this update was tempted to adjust his track northward on the basis of these models). The other line of thinking is that the ridge remains strong and guides the storm to the west and has it makeing landfall in central Florida and proceeding to the northwest. The National Hurricane Center forecast is currently on this line of thinking. Florida State's Super-ensemble model output was a bit further south than the NHC forecast. The most recent run had the storm making landfall in Palm Beach, turning to the northwest, cutting across the peninsula into the Gulf of Mexico, before making a second landfall in the vicinity of Appalachicola. (Although there may have been a more recent run as the NHC discussion says that their forecast is on top of the Super-ensemble's track). My synpotic meteorology professor continues to support the southern track. He thinks some forecasters are paying too much blind attention to the model output and are not doing enough thoughtful anlaysis (such as looking to see which are handling the ridge correctly and which are not). He is bothered by the fact that the storm has not slowed and hadn't shown much sign of making a turn to the northwest. (Although, when I look at the last few frames of the visible satellite loop, I do see a bit more of a northwest heading then there was earlier this afternoon). As far as strength goes, Frances continues to have textbook appearance and there doesn't appear to be anything to weaken it. Any fluctuations in strength would be the result of internal eye-wall dynamics. Of course, the storm is the topic of discussion in any conversation among the meteorology students and apparently some were talking about going into the path of the storm. The head of the Meteorology Department at Florida State issued this message to his students It has come to my attention that some individuals plan to engage themselves in the practice of storm chasing. While it is understandable why some of you might find this activity appealing, it is fraught with danger and can lead to severe injuries and possibly death. If you should be doing this, do NOT identify yourselves as representing the Department of Meteorology or the University, as it is our policy not to endorse, approve or participate in this activity. ---------------------------------------------------------------------------Palm Beach County is one of the first to start evacuations, as is Volusia County . In the wake of Charley, the evacuation orders are being extended to mobile homes as well as homes in low-lying areas. 300,000 urged to evacuate in Palm Beach County (Palm Beach Post)
Cancellations abound. Broward County schools are closed tomorrow
and Friday and Miami-Dade is considering folllowing suit. Palm
Beach county is closing schools early on Thursday and will be closed on
Friday. Volusia county schools are closed tomorrow and Friday,
and most other surrounding counties along I-4 have cancelled school for
Friday. Mandatory evacuation planned for Volusia barrier island, mobile homes (Daytona Beach News-Journal) Hurricane Frances Closings (Palm Beach Post)
Finally, the FSU-Miami game, scheduled for Monday night may get pushed back to Sep 11.Frances may postpone FSU-Miami game (Palm Beach Post)
Weather comment []5:45:35 PM trackback []
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| At 2 AM EDT Frances was 210 miles east of Grand Turk Island and moving to the west-northwest at 17 mph. Winds and central pressure are unchanged (140 mph and 939 mb). The forecast landfall point is actually pretty close to where it was last night, despite all of the variations in the past 24 hours. The difference is that immediately after landfall (on Saturday), the forecast takes the storm almost due north parallel to the Florida coast. The forecast discussion gives three distinct forecasts among the models. One forecast takes the storm to South Carolina by the end of the five day period. Another takes the storm to central Florida in a similar time period. The third puts Frances in South Forida in three days. The models that put the storm in South Carolina have been the worst at handling the ridge that is guiding Frances to the west, so its forecast was pretty much rejected. With the 72 hour forecast putting the storm over the western-most Bahamas on a track south of northwest, it is hard to see how a landfall in Florida will not occur. Nevertheless, people north of Florida up to North Carolina should pay attention to Frances as well until the situation resolves itself a bit more. Weather comment []2:30:50 AM trackback []
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© Copyright
2004
Charles Fenwick
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Last update: 10/2/2004; 11:03:37 PM .
Last update: 10/2/2004; 11:03:37 PM .
