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Disturbance 96L near tropical depression strength

By: Dr. Jeff Masters, 4:12 PM GMT on September 24, 2006

A tropical wave (dubbed "96L" by NHC) is in the mid-Atlantic, 1200 miles east of the northernmost Lesser Antilles Islands. The storm has developed a well-defined circular rotation visible on visible satellite animations, and is close to tropical depression status. QuikSCAT winds from this morning's 4:45am EDT pass were 25-35 mph in a few isolated patches. About 20 knots of winds shear from the west is keeping the heavy thunderstorm activity of 96L confined to the east side of its circulation. If this shear relaxes for 12 or so hours, the storm has a chance at organizing into a tropical depression.

The computer models indicate that wind shear may drop enough to allow 96L to organize into a weak tropical storm, but none of the models are forecasting a hurricane. The storm is currently drifting slowly to the northwest. As the remains of Hurricane Helene race off to the northeast over the next few days, the Bermuda High will re-establish itself and a high pressure ridge will build in, forcing 96L to the west-northwest. The system could threaten Bermuda around Friday. However, I think it is likely that a trough of low pressure will recurve 96L northwards and out to sea before it reaches Bermuda.


Figure 1. Preliminary model tracks for Invest 96L.

Elsewhere in the tropics
Hurricane Helene has completed its transition to an extratropical storm, and its remnants may bring high winds and heavy rain to Ireland on Wednesday. A few of the computer models are forecasting that a new tropical storm will develop between Africa and the Lesser Antilles later this week. Any development in this region would likely recurve northwards out to sea.

I'll have an update Monday morning.
Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.