Sunday, September 09, 2012

Tropical Storm Leslie, Hurricane Michael, and the Atlantic Blobette: September 9, Update A

One more day until you stop hearing about Bermuda and Leslie. One more day until Michael is no longer a hurricane. One more day until Andy Murray wins a Grand Slam. :-)

Tropical Storm Leslie
She is crossing the latitude of Bermuda at the moment and although officially at the last advisory an hour ago, she was at 32.6N, 62.4W heading N at 10mph, I think she has started on her NNE/NE track and is now at 32.8N, 62.2W. Here is the latest infrared satellite image:

It looks like Bermuda got some thunderstormy weather and may (or may not) have another bout. Even though there are areas of (strong) convection, it is not very symmetrical and I agree with the official analysis that she's still a Tropical Storm with winds of 60mph, central pressure 988mb. Although the sea surface temperatures are still 28 deg C, there is a bit of wind shear to her north and she has that lovely dry air that is inhibiting her development. You can see the wind shear in this satellite image of the Northwest Atlantic:

She's heading NNE now, but that really long front coming off the US brings with it large wind shear. Later today it will start impacting Leslie with its wind shear, and once it gets closer to Leslie, she will jump on this highway and get whisked away to the northeast.  Circulation is good in the lower half of of the troposphere, with a small signal in the upper troposphere.

Hurricane Michael
You can see little Michael in the image of the NW Atlantic as well. He still has a pretty nice eye and his convection is still pretty weak. Officially he was at 33.7N, 43.2W heading W at 5mph at the last advisory. Winds are now down to 90mph, central pressure is 978mb. Yay! I agree with this wind speed now, and it makes him a strong cat 1 storm. Until his eye vanishes, I'd keep him at this intensity. Yesterday the NHC did an excellent job with forecasting his sharp left turn. It looks like he's moving slightly south of west... heading towards Leslie. I don't think he'll get far enough west to actually meet her, but he'll be interacting with her outer bands as she moves Northeastward just because she is so big.

Atlantic Blobette
A small blobette came off Africa a couple of days ago and is now west of the Cape Verde islands at around 15N, 30W, heading WNW at 10-15mph. There is a little circulation in the lower troposphere and nothing in the upper troposphere. There is also not a lot of convection in this system yet. The NHC give it a 40% chance of developing in the next 48 hours. It looks like it will continue westward, or it may get stuck or move WSW. It is really not well developed enough to be able to assess clearly at the moment. I'll keep an eye on it though.

I hope things are going ok on Bermuda... let me know if you can!

Tally ho!

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DISCLAIMER: 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 "run away, run away" (Monty Python), I'll let you know.

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