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No Wilma tonight

By: Dr. Jeff Masters, 1:49 AM GMT on October 17, 2005

Tropical Depression 24 remains unimpressive tonight; satellite imagery continues to slow a large and poorly organized system that is not yet a tropical storm. The wind shear above the storm is still very low--less than five knots--but the upper-level anticyclone that was on top has become less well defined, and dry air continues to intrude into the northwest side of the storm. The last hurricane hunter mission left the storm at 4:30 pm EDT today, so the exact strength of the storm is not known at this point. There is not another mission scheduled until 2 pm EDT Monday. The NOAA jet is scheduled to make its first flight Tuesday afternoon.

The forecast guidance still predicts that this will be Tropical Storm Wilma on Monday, and Hurricane Wilma by Wednesday. This storm reminds me of Rita, which spent about three days trying to organize in the Bahamas before finally solidifying its inner core and rapidly intensifying. This storm may behave similarly, and intensificatiion into a major hurricane by late in the week is a possibility that several of the computer models are calling for.


Figure 1. Historical tracks of tropical depressions that have formed in the western Caribbean in October.

Steering currents are expected to remain weak the next three days, and some erratic motion is possible. However, a mostly west or west-northwest should result in a landfall on the Yucatan or Belize late in the week. A weak trough that was expected to deflect the storm to the north before this happened is now forecast to be too weak to significantly affect it. However, second a low pressure system currrently bringing rain to southern California is expected to move east this week and push a trough far enough south to pull the storm to the north and into the Gulf of Mexico late in the week. An eventual landfall on the west coast of Florida 7 - 8 days from now is expected. This is a typical track for October systems forming in the western Caribbean, as we can see from the historical track map shown in Figure 1. It still looks unlikely that this storm will get "stuck" in the Caribbean and drift southwest towards Honduras like Category 5 Hurricane Mitch did in October 1998. It also appears unlikely that Gulf Coast residents of Louisiana and Texas will receive a direct hit from this storm, although it is difficult to accurately forecast what might happen beyond five days when we are so poor at just three day forecasts.

Elsewhere in the tropics, nothing else is happening. I'll be back with a update in the morning about 9:30 am EDT.

Jeff Masters

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