01 September 2013

Disturbance heading into eastern Caribbean

An easterly wave that left the African coast about a week ago is just about to cross the Lesser Antilles and enter the eastern Caribbean.  It has been inactive for most of the journey, but has gained organization and persistent deep convection over the past 24 hours.

Enhanced satellite image over the Lesser Antilles on Sunday afternoon.  (NOAA)
The environmental conditions are presently conducive for further development, and are expected to remain so for at least the coming week.  It is in 5-10 kts of vertical shear, over 29C sea surface temperatures, and the mid-level humidity is high enough to support growth.  You can view a radar loop of it as it passes through the islands here (new frames continuously added, so check back later too).

Forecasts of intensity, track, shear, SST, and mid-level humidity from a small selection of models.
So, we will clearly have to watch this closely, as model solutions range from near-nothing to a Category 3 hurricane in 5 days near Jamaica.  Right now, it's too soon to get concerned, but not too soon to pay attention.  HWRF, the model solution in blue on the plot above, is interesting because it has the storm becoming a minimal hurricane by mid-week, then weakening slightly as it crosses Haiti and eastern Cuba, then picking back up with a possible track toward south Florida next weekend.

5-day forecast from an HWRF run today... valid Friday afternoon.  The colored contours are surface wind and the black line contours are surface pressure.

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