Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather
By: Dr. Jeff Masters , 4:17 PM GMT on October 16, 2011
A large low pressure system centered over the eastern Yucatan peninsula, near Mexico's Cozumel Island (Invest 95L), is bringing heavy rains to Western Cuba and the Yucatan Peninsula. Rainfall amounts of 5 - 10 inches have fallen over Central and Western Cuba since October 9, according to radar rainfall estimates from the Key West Radar. Heavy rains have also affected portions of the Florida Keys; a personal weather station on Plantation Key recorded 2.28" of rain so far this weekend. Satellite loops show that 95L does not have a well-formed surface circulation, but the storm does have a respectable amount of heavy thunderstorm activity that is increasing in intensity and areal coverage. Surface observations in the Western Caribbean reveal that 95L has a broad counter-clockwise circulation. A ship in the Yucatan Channel recorded sustained winds of 44 mph this morning, and another ship measured sustained winds of 39 mph about 30 miles southwest of Key West, but no land stations are reporting winds over 30 mph. Water temperatures over the regions are near 29°C, which is plenty warm to support a tropical storm.
Figure 1. Afternoon satellite image of Invest 95L.
Wind shear over 95L is currently a moderate 10 - 20 knots, and is expected to stay in the moderate range over the next three days. This should allow 95L a decent chance to develop into a tropical depression, once it pulls away from the Yucatan Peninsula on Monday. NHC is giving the system a 50% chance of developing into a tropical depression by Tuesday, and has scheduled a hurricane hunter aircraft to investigate the system on Monday afternoon. I'd put the odds of development higher, at 70%. All of the models are showing only weak development of 95L. The storm is currently moving northwest, but should turn north and then northeast by Tuesday, as it gets sucked into an approaching trough of low pressure. This trough should pull 95L into the west coast of Florida on Tuesday, and the southwest portion of Florida could receive up to 6 inches of rain from 95L. Once 95L meets up with the trough, wind shear will rise sharply, and it is unlikely 95L will be able to grow any stronger than a 50 mph tropical storm before landfall occurs along the west coast of Florida. It is more likely that 95L will have top winds of 35 - 45 mph at landfall on Tuesday.
Another area of disturbed weather in the Eastern Atlantic, 1500 miles east of the Lesser Antilles Islands, has developed a modest degree of spin, but has very limited heavy thunderstorm activity. NHC is giving this system a 10% chance of developing into a tropical depression by Tuesday.
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