August 23, 2012

An Overview of Tropical Activity

Isaac had quite a night last night, and one that could potentially have a large impact on his long term track, but may not. What it does do with certainty is introduce even more uncertainty into the forecast. As he passed through the Leeward Islands, Isaac developed multiple vortices competing for dominance. At one point, it even looked like two tropical storms right next to each other, straddling the Leewards. Though it appears he’s starting to shake that off (though I still see signs of multiple vortex competition), it’s left him continuously left of track – or more southerly. This could potentially mean that this will move the whole track to the left – taking all but the Panhandle out of the picture. In fact, if it gets completely missed by this trough and continues west, Louisiana, Mississippi, and Alabama may want to pay attention. But, a track further south means that if he gets his organization sorted out, he will be more over water and farther from the mountainous terrain of Hispaniola and Cuba. This would result in greater strength, a greater poleward motion; we may just be taking a different path to get to the same spot. With the storm still potentially traveling over mountainous areas, intensity still remains very uncertain. However, there does appear to be sufficient conditions for Isaac to become a hurricane on the north side of the Greater Antilles. The extreme left outlier model, the Euro, has moved back from a Louisiana landfall yesterday to Pensacola. That implies that this is still a Florida issue, but we’re still obviously working with a pretty low confidence forecast here. The continued prudent strategy continues to be for all points in Florida to be prepared for hurricane conditions.
Tropical Depression 10:
Further east, Tropical Depression 10 continues to remain poorly organized. It has received more model support for even existing in the short term, but continues to find trouble garnering support for a long life. Ten will become Joyce later this morning. She is still not likely to be a very strong tropical storm, as the forecast track brings her up into an area of higher shear and drier air. Should she survive a significant period of time, the recurving Isaac (or his remnants) should safely recurve Joyce far from all land but Bermuda. But there’s no guaranteeing this storm would even make it that long. Unexpected changes to Isaac’s track may have some impact down the line on this storm.
By Sean Luchs, Meteorologist - Florida Forest Service

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