Wednesday, October 02, 2013

Tropical Depression Jerrry and the Caribbean Blobette: October 2, Update A

101 reasons why Monarchs are useful. Number 25: "Australia had a government shut down once. In the end, the Queen fired everyone in parliament." They haven't had a shutdown since. (From the Washington Post: ;-) (thanks to Trent F. for pointing that article out).

Tropical Depression Jerry
Although he still has circulation in the lower half of the troposphere, he hasn't been able to get a handle on the convection at all, poor fellow. The NHC just downgraded him to a Tropical Depression. Winds are now officially around 35mph, central pressure is 1010mb. He's moving to the NE at 7mph - along that far more reasonable track. They have him as a depression all the way through to Sunday at least, but it looks like there is wind shear and the circulation is slowly  dwindling, so I'm not sure he'll hold out that long. He is currently at around 29.7N, 42W (and has therefore discovered the meaning of life, the universe and everything... no wonder he's now a Depression! ;-)).

Caribbean Blobette
Onto the newest kid on the block. Although the NHC have said there is no closed circulation and they had a plane fly into the system, I think they are a bit mistaken. She's a good looking little storm now and has some decent circulation throughout the lower troposphere. I would have named her TS Karen by now. She's got more structure and convection than Jerry:

At a guess, I'd say she had a center somewhere around 20.5N, 85.2W. She is moving NW and towards the Gulf.

Now, as it says on the cover of Hitchhikers Guide To The Galaxy: Don't Panic!

She's interacting with land - both the Yucatan and Cuba and although she has a lot of convection, she is moving over the warmest part of the Caribbean, where sea surface temperatures are 29-31 deg C!! and the upper ~150m of the water column is warmer than 26.5 deg C!!! How could she not be generating thundery rainstorms? The wind from the flapping wings of a seagull flying over that would probably create a small storm! So, that explains the convection. When she gets into the Gulf, although the surface waters are still around 29 deg C, only the upper 50-75m of the water column is warmer than 26.5 deg C.

Meanwhile in the atmosphere it looks like she'll run into some drier air in the Gulf:

And wind shear will get a little stronger.

To sum up, I think she's already a Tropical Storm, but she's not a very strong one (yet anyway) and I'm not yet sure that she will be very strong once she's in the Gulf.

As for track, I still think there's a possibility that she'll head a little more to the west - maybe enough to go over the Yucatan peninsula (which may weaken her further). It's a little tricky to do a forecast on where she'll go in the Gulf until she gets into the Gulf and we see what shape she's in. All those in the Gulf (including us in Florida) should keep an eye on her (just one eye for now will suffice ;-)).

Maybe we'll wake up to Tropical Storm Karen!
More tomorrow. Time for a nice nap now. :-)

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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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