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Atlantic Tropical Weather Update 8/31/09

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Invest-94 continues to exhibit increasing organization today, while the banded cloud features are only moderately impressive.  The system still doesn’t have a dominant central low pressure center.  This disturbance is definitely still a tropical wave, not yet a tropical depression.

Invest-94’s general center of circulation is located near 15.6N, 53.4W (~500 miles east of the Windward Islands) ; is moving WNW @ 14mph; and has maximum sustained winds of 30mph.

The disturbance’s movement in the past 12+ hours has taken it more northerly than I thought it would last night.  It should continue its WNW/NW movement throughout the next day or so.  After that, there is considerable divergence of model track solutions.  The NOGAPS keeps moving the storm NW, while the GFS, LBAR and BAMM shift its track to almost due west after Day 2.  The HWRF comes up with a snaking pattern: WNW, W, then WNW again in days 4-5.  The multitudes of track solutions means that anything from no impact on islands is possible, as is a glancing blow to the northern Windward Islands, Puerto Rico and Hispanola.

Continued organization and intensification is also progged by models, but this was the case all day yesterday as well.  The only thing to take from this is that intensification to Tropical Depression status is likely in the next day or so.  SSTs are plenty warm and the system will encounter less wind shear as it continues to travel across the basin.

Much further east, another tropical wave is exiting Africa over the Atlantic.  This wave is fairly far north – about 12.5N or so.  It isn’t that vigorous either.  A wave still over Africa looks a little better on satellite imagery.  It will be many days before either of these disturbances make their mark on the Atlantic basin, if at all.

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