15 August 2007

Dean and Erin both strengthening...

TS Dean has shown a solid trend of intensification, though not rapid yet.  An important transition has taken place where scattered deep convection has given way to more concentrated centralized deep convection.  The core appears to be trying to form the beginnings of an eyewall at the time of this writing (18Z).

Dean's intensity was estimated at 50kts and 997mb at 15Z.  The heading is W at 17kts.  Vertical wind shear is fairly low (10kts) from the north and should decrease as time goes on.  SST is around 27.5C and will increase to 30C over the next 5 days.

The latest long-range forecast takes Dean through the central Lesser Antilles in two days, south of Hispaniola in 4 days, and near Jamaica in 5 days, all as a strong or major hurricane.  Recent model runs suggest that the trough off the US east coast will not be as potent as suspected yesterday, which means that the hurricane is less likely to be nudged northward out of the Caribbean Sea.

At 15Z today, TD5 was upgraded to TS Erin in the central Gulf of Mexico. Intensity as measured by aircraft is 35kts and 1005mb.  It's over 30.5C water which is more than ample for a storm to fuel itself, and vertical shear is neglibly small.  However, the thing working against it for further intensification is time.  In one day, it will be onshore near Brownsville TX.  A Tropical Storm Warning is already in effect for the southern half of the TX coast.

Please visit my tropical Atlantic headquarters.

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