Sunday, August 29, 2010

Hurricane Danielle, Tropical Storm Earl and the Atlantic Blobette: August 29, Update A

Tropical Storm Earl:
I thought I'd start with Earl, as it's he's the main feature for the next few days. In the last few hours he's started to look more like a hurricane, and the center seems to be around 17.1N, 57.6W. His maximum winds are 70mph (TS range: 39-73mph) so he's a strong Tropical Storm/borderline hurricane. Central pressure is estimated to be 985mb. He continues to move W at a fairly fast 18mph.  
Although he's lacking in organization he certainly does have a lot of convection so there will be some heavy thunderstorms around. The convection is mostly to the south and west of his center of circulation at the moment, because of the wind shear effects from Danielle that I mentioned yesterday. His vorticity has increased though and now reaches the upper troposphere. It's at the sort of levels I see with a cat 1 or 2 hurricane, so I expect he will be officially upgraded in the next advisory later this morning.
It looks to me as if he's going to remain on a westward track and hit the Northern Leeward islands (they are already experiencing his outer bands). There's a small chance he'll make that Northwestward turn and just catch everyone on his south side, but if that's going to happen with that wind shear it means that they will experience the worst of the convective activity. But I think there's a better chance he will continue westward for a little while longer (remain on the southern edge of the cone of possible tracks) and just enter the northern Caribbean and then make that northwestward turn, possibly in the vicinity of the US Virgin Islands or Puerto Rico.  If he does that, the eye will be to the south and they will get the northern side of the storm - interestingly, if wind shear continues, it means that the worst of the weather will remain to their south (in a fully formed hurricane, this is not usually the case). Of course, Danielle is moving NE and further away, therefore the strong wind shear from the north east will diminish with time, giving him an opportunity to develop on all sides. Regardless of exact path, the islands will get some stormy weather. I heard from Tom J. on St. Thomas that their hurricane preparations will be completed today and the palm trees have already begun to sway. The islands in that corner of the Caribbean are under a hurricane watch or warning.
Hurricane Danielle:
Circulation (vorticity) is still strong throughout the troposphere for Danielle, so she'll remain a hurricane for a little longer. She's slightly stronger than Earl at the moment, however she's about to head into an area of strong wind shear which will knock her socks off. She's currently at 34.6N, 55.4W, with winds of 90mph, making her a cat 1 hurricane (range: 74-95mph) and central pressure of 972mb. She's moving NE at 21mph. Not much more to say about this one for now.
Atlantic Blobette:
Circulation (vorticity) for this blobette has not changed since yesterday, and wind shear remains fairly weak. However it is still surrounded by dry air, which may be the inhibiting factor (for now). Convection has weakend a little in the past few hours, but in my opinion this is a Tropical Depression (not a Tropical Storm yet) and has been since yesterday. The center is somewhere in the region of 13.5N, 36.2W. Again, I don't know what the delay is in upgrading it.  
It's your lucky day (!?!?) ... you'll get two updates today!
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These remarks are just what I think/see regarding tropical storms - not the opinion of any organization I represent. If you are making an evacuation decision, please heed your local emergency management and the National Hurricane Center's official forecast and the National Weather Service announcements. This is not an official forecast. If I was there and was going to "run away, run away" (Monty Python), I'll let you know.

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