Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 7:20 PM GMT on August 09, 2006
The Hurricane Hunters just finished investigating the tropical wave moving into the Lesser Antilles Islands, and found no closed surface circulation. The top winds were 34 mph at flight level of 1000 feet, and 23 mph at the surface. Wind shear of 10-20 knots due to upper-level winds from the southeast are interfering with this storm's organization, and have blown the main area of thunderstorms away from the center to the northwest of the storm. Strong upper-level westerly winds from an upper-level low pressure system to the north are expected to bring significant amounts of shear over the system for the next two days. The shear may weaken enough to allow a tropical depression to form in the next day or two, but it will be a struggle for this system to get organized. There are the beginnings of some upper level outflow apparent on satellite imagery, but no real low-level spiral banding occurring yet. Pressures are falling and it has been raining at Barbados, Martinique, and St. Lucia, but winds have been under 20 mph, except at Martinique, where the wind gusted to 52 mph at 3:23pm EDT. Martinique/Guadaloupe radar presents a nice picture of the storm's rainbands.
This morning's GFDL model continues to predict that the wave will develop by Thursday into a weak tropical storm, which will move through the Caribbean Sea to a point south of Haiti on Saturday, where high wind shear will dissipate it. None of the other computer models develop the storm at all.
The wave will move through the Lesser Antilles Islands tonight and Thursday morning, bringing winds of 20-30 mph and heavy rain to Barbados, St. Lucia, Martinique, and surrounding islands. Puerto Rico and the Dominican Republic may also receive these effects, on Friday and Saturday, respectively. The Hurricane Hunter mission for tonight was cancelled, and has been rescheduled for 2pm EDT Thursday.
Figure 1. Preliminary model tracks for the Lesser Antilles tropical wave.
Elsewhere in the tropics
A broad non-tropical low pressure system located about 800 miles southwest of the Azores is drifting southward, and is not expected to develop over the next two days. Some of the computer models are forecasting that development is possible by Sunday or Monday, though.
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