New disturbance 99L near Bermuda headed out to sea

An area of disturbed weather near 30N, 70W, about 300 miles southwest of Bermuda, has been designated "Invest 99L" by the National Hurricane Center this morning. Radar animation from Bermuda shows a large area of heavy rain over the ocean to the east of the island. This area of disturbed weather is moving to the north-northeast, and is expected to turn eastward this weekend. Some of 99L's heavy thunderstorms may affect Bermuda tonight and Saturday. The QuikSCAT satellite pass at 6:15am EDT this morning found a large, well-defined surface circulation, and peak winds in the 20-25 mph range. The disturbance is under 30 knots of wind shear from strong upper-level westerly winds. This shear is preventing heavy thunderstorms from building on the west side of 99L. Wind shear is expected to be in the 20-40 knot range for the next two days. The disturbance is over warm waters of 28 degrees C, but water temperatures cool rapidly to 26C just north of Bermuda. Between the wind shear and cooler waters, I doubt 99L has time to organize into a tropical or subtropical depression.


Figure 1. Preliminary model tracks for disturbance "99L".

Elsewhere in the tropics
An area of disturbed weather continues over the southern Gulf of Mexico, but is not expected to develop due to 20 knots of wind shear. High wind shear dominates most of the rest of the tropical Atlantic. This shear is forecast to relax early next week over the Caribbean and southern Gulf of Mexico, so we'll have to keep an eye on these regions next week.

Jeff Masters