Tropical Storm Ernesto

August 25, 2006

The huurricane hunter is in Tropical Depression 5 and finding flight level winds that convert to surface winds of about 45 mph, which is above the threshold for a tropical storm, and it will be rated as such in the 5 PM advisory package.

It’s an upgrade that comes  a little bit later than expected.  Late last night I thought that the depression would be probably upgraded at 5 AM as the satellite intensity estimates ranged from 35-50 mph and the storm’s appearance was improving during the time those estimates were made and when the advisory was written. The advisory however, did not change the storm’s classification, however, citing concerns over that the center of the storm was not where the intensity estimates placed it, (which would cause the estimates too high).

Dr Masters thought the upgrade would come at 11 AM, again concerns over the location of the center were cited as the reason for not upgrading,  despite even more evidence that the system was at tropical storm strength.

As was the case yesterday, the big short term question is upper level shear over the central and eastern Caribbean. This morning’s  5 AM discussion explains the dilemma. There are destructively high levels of shear in the central Caribbean, and the storm would have slim prospects for survival if that were to remain the case. However, the global forecast models move the feature causing this shear to the weast, thereby creating a favorable enviroment for the storm. But, the global models are known to forecast such events poorly at times, so one can’t put too much wait in them.

To an extent the situation is the reverse of the dilemma faced by Tropical Storm Chris. Chris needed to race away from an upper level low that was gaing on it.  Ernesto has an upper level low to the west of it and needs to move slower than it to survive.

At the moment Ernesto is in an area of increasing shear that’s 10-20 knots in magnitude and not faring well as current appearance on satellite is worse than this morning. The next few hours will tell us whether there is going to be another storm buried in the East Caribbean graveyard.


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