06 August 2012

Ernesto strengthening, Florence vanishing

Beginning Sunday evening, Ernesto experienced a resurgence in deep convection, and that trend has continued into Monday morning.  Several factors have likely led to this transition: the environmental TPW is quite a bit higher now that the storm is further west into the Caribbean, the vertical shear is back down to under 10kts, and the forward speed has slowed from a breakneck 20kts to a normal 10kts.  The cloud tops in this infrared satellite image are reaching as cold as -85C (-121F) which is indicative of very vigorous deep convection driving the clouds high into the atmosphere.

At 09Z today (5am EDT), the intensity was 45kts and 1003mb and will likely be stronger by the 11am EDT advisory.  The center was located about 170 miles east of the Nicaragua/Honduras border and tracking due west at 10kts; on that trajectory, the center will reach eastern Honduras late tonight -- but the outer circulation and rainbands will affect land very shortly.  I have a long-range radar loop from Belize available which reaches out to central Honduras.

The forecast for Ernesto is becoming rather simple.  The model guidance is in amazing agreement on the track passing just north along the coast of Honduras today and Tuesday, then a landfall on Belize early on Wednesday as a strong tropical storm.  Of course, there is a possibility that it could achieve hurricane status by then.  The official NHC forecast is shown below, along with the relevant watches and warnings.  The full and most recent graphic can be found here.

On to Florence... the enormous amount of dry air surrounding this storm has overwhelmed and choked off all convection.  It is now a weakening Depression and only a low-level swirl located about 1000 miles west of the Cape Verde islands.

Elsewhere, another easterly wave exited the African coast yesterday, but models have been dissipating it rather quickly.

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