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 , 3:59 PM GMT on September 29, 2013
A low pressure system (Invest 97L) over the Central Caribbean is generating heavy rains from Haiti to Panama, and is moving northwest at about 7 mph. Satellite loops show 97L has a modest area of disorganized heavy thunderstorms and a broad area of spin. Dry air covers the Northwest Caribbean, and this dry air is slowing development. Ocean temperatures are a very warm 29°C (84°F), and wind shear is a high 20 knots.
Figure 1. Latest satellite image of Invest 97L.
Forecast for 97L
Marginally favorable conditions for development are expected for the next five days, according to the latest SHIPS model forecast, with moderate levels of wind shear (10 - 20 knots), but an atmosphere that will grow drier as 97L approaches the Northwest Caribbean and Southeast Gulf of Mexico. None of the reliable computer forecast models develop 97L into a tropical depression over the next five days. These models (the GFS, ECMWF, and UKMET) predict a northwesterly track for 97L over the next three days, followed by a more northerly track over Western Cuba and just west of the Florida Keys late in the week. On this path, 97L will bring heavy rains of 2 - 4" to Jamaica and Southwest Haiti on Sunday and Monday, to the Cayman Islands and Central and Eastern Cuba on Monday and Tuesday, to Western Cuba on Tuesday and Wednesday, and to South Florida on Wednesday and Thursday. In their 8 am EDT Sunday Tropical Weather Outlook, NHC gave 97L 2-day odds of development of 20%, and 5-day odds of 40%.
Figure 2. MODIS satellite image of TD 11, taken at 10:30 am EDT on September 29, 2013. Image credit: NASA.
Tropical Depression 11 develops in the Central Atlantic
Tropical Depression Eleven formed from a tropical wave in the Central Atlantic on Saturday night, but the storm is far from land and is not likely to threaten any land areas. Wind shear is currently keeping TD 11 disorganized, with just a small area of heavy thunderstorms displaced from the center of circulation. By Monday, the upper-level low bringing the shear should move away, allowing TD 11 to intensify into Tropical Storm Jerry.
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