Sunday, August 29, 2010

Hurricane Danielle, Hurricane Earl, and the Atlantic Blobette: August 29, Update B

Hurricane Earl:
Earl is now a mid-sized cat 1 hurricane with winds of 85mph (cat 1 range: 74-95mph) and a central pressure of 978mb. He's heading WNW at 14mph and his center is at 17.6N, 59.7W. This means that he will pass just (barely) north of the leeward islands. Planes have been flying into the system and will continue so, so the wind speed and pressure will be based on direct in-situ observations. Interestingly, the forecast for the next 20 hours is for Earl to become a major hurricane when he is just north of the Virgin Islands. I don't know if he'll be a cat 3 or higher but I think there's a very good chance he'll be a cat 2. Convection is pretty good, although still mostly to the south at the moment, and it looks like the wind shear will decrease soon. Surface water temperatures are over 30 deg C, with waters as warm as 26.5 degrees down to 100m. Two factors that might keep him in check for a couple of minutes are the very very limited impact that the islands themselves will have on him, and the surrounding dry air (also limited). Hmm... having looked at the pressure fields, I can see the reasoning for the forecast to make him into a cat 3 just north of the islands. It looks like he will slow down in his forward motion, keeping him over that area for some time, which would then allow him to pick up in intensity without making much progress in space. He has already slowed down.  I also wouldn't put it past him to move WNW for a short while, and then move W again but maintaining his speed. One thing to watch for is how much he slows in the next 24 hours.
Hurricane Danielle:
She's still hanging on as a cat 1 hurricane with estimated winds of 80mph and central pressure of 977mb. I don't think she's really that strong - there's no convection to the south side of the center, and whatever there is to the north is not very deep - maybe some rain, but no thunder. She's moving NNE at a really rapid 29mph, and the center is at 38N, 54.5W. She's not forecast to reach land on this side of the pond (i.e. she's not heading in my direction), but I'll continue with brief updates for another couple of days, in case some fish are reading this and have relatives in her path.
Atlantic Blobette:
The NHC still have this listed as an 80% chance of tropical cyclone formation in the next 48 hours. As I said earlier, I think this is already a Tropical Depression. There is definitely a closed circulation with winds less than 39 mph. I would say that it's quite weak on the convection side of things, with just some rain but no thunder, but I'm not calling it a Tropical Storm, just a TD. It's that surrounding dry air that's getting into it. But circulation is strong, so there's a chance it will pick up as it continues to move west (at 20mph).  
More tomorrow!
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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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