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 , 1:46 PM GMT on August 19, 2006
The persistent low pressure system about 50 miles east of Jacksonville Florida continues to kick up heavy thunderstorms and high winds over the waters off the Florida coast. Wind shear from a protuberance of the jet stream is still a very hefty 40-50 knots, and is expected to remain over 40 knots through Sunday, so development of this system into a tropical depression is not expected. However, radar animations out of Jacksonville, FL show a healthy circulation and some strong thunderstorms on the east and south sides. Wind speeds at a buoy 45 miles east-northeast of St. Augustine have been about 25 mph gusting to 30 mph this morning. A QuikSCAT satellite pass at 7:06am EDT this morning showed some wind gusts as high as 45 mph in some of the thunderstorms. The low could affect Georgia and northern Florida today and Sunday much as a tropical depression would, bringing heavy thunderstorms and gusty winds.
Figure 1. Current radar out of Jacksonville, FL.
Figure 2. Preliminary models tracks for the East Coast disturbance.
Elsewhere in the tropics
The strong tropical wave south of the Cape Verde Islands that the GFS model had been developing into a hurricane is now pretty ordinary looking. The GFS no longer develops this wave. A good general rule for model predictions of tropical storm formation:
1) If two or more of the reliable models (GFS, NOGAPS, GFDL, UKMET) are forecasting develoment, watch out.
2) If none of the reliable models are forecasting development, watch out. The models miss most tropical storm development.
3) If just one of the reliable models is forecasting development, you can probably discount it.
That being said, we have a case where two reliable models--the GFS and NOGAPS--are forecasting that the large tropical wave that will move off Africa Sunday will develop into a tropical storm by the middle of next week. However, the wave will have to contend with a large cloud of Saharan dust which has just emerged from the coast of Africa.
Wind shear remains high over the Caribbean today, but the GFS is forecasting that this will drop significantly by Wednesday, and remain very low for the ten days following. I expect at least one tropical storm will form in the Atlantic during the next seven days. One candidate might be a weak tropical wave currently in the mid-Atlantic near 11N 40W.
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