Ernesto Still Weak but Better Organized, Likely to Become a Hurricane Threat

   Posted by Levi at 7:06pm on August 4, 2012

Ernesto has become better organized since yesterday with a persistent CDO and expansion of the spiral bands and upper-level outflow. However, recon this morning found that Ernesto has not strengthened since yesterday, and the central pressure is actually up a few millibars. The impressive organization of Ernesto with this high of a pressure came as a surprise to me, but the idea that this storm would halt intensification upon entering the Caribbean until about 75W has verified nicely so far. I explain in the video my theory as to why Ernesto has been firing all of this convection without strengthening.

Once past 75W, or about the longitude of Jamaica, conditions will rapidly improve for Ernesto as the upper-level pattern allows expansion of upper ridging above the storm, and the trade winds slow down in the western Caribbean, both of which should allow pressures to fall and the storm to strengthen. We could see Ernesto quickly become a hurricane in the western Caribbean, and a big problem for the Yucatan Peninsula. If Ernesto crosses a portion of the Yucatan it will knock it down, but Ernesto may reach his peak intensity afterwards in the Gulf of Mexico.

Ernesto’s track is still the toughest part of this forecast. It will largely be a function of his intensity, since a stronger storm will tend to move more northward into the weakness in the steering ridge that will be over the north gulf coast over the next several days. The forecasted pattern consists of not a wide open trough, but rather a large area of sprawling, light, erratic winds over the Gulf of Mexico, indicative of a weak steering pattern that a strengthening Ernesto will likely start to turn more northwest into while moving slower. I believe this will eventually take Ernesto near the northeastern Yucatan, and then into the western Gulf of Mexico. The largely uncertain part of the forecast is where the second landfall in the Gulf of Mexico will be. Right now I am leaning towards the idea that Ernesto will be guided back towards the WNW by the Texas ridge into northern Mexico or southern Texas, a solution supported by last night’s ECMWF ensembles. However, this is still 6-8 days out, and if we have a particularly powerful hurricane moving far enough north in the NW Caribbean, the door could open for a track into the north gulf coast instead, so the entire north and west gulf coasts and the Yucatan Peninsula should closely monitor Ernesto, as he could become a big problem down the road.

We shall see what happens!

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