Friday, August 19, 2011

Tropical Depression 8, the Atlantic Blobette and Blob: August 18, Update A

Ben in California finally figured it out… apparently I missed the memo saying that any storm that is about to make landfall would be waaay too obvious to name, so this year they would only name tropical storms if they were in the Arctic. Sigh. ;-)

The NHC finally decided to upgrade my Caribbean Blob to an official Tropical Depression (number 8). It is, of course, already interacting with the central America land mass and is practically on top of Nicaragua/Honduras at this point so I don’t know if it will even have a chance to be named (I think they might have missed the boat on this one). It is heading West at 12mph, central pressure 1006mb, winds 35mph. Fortunately there isn’t much convection to this blob, certainly not as much as there was a couple of days ago anyway, and the winds are fairly light so it should all be groovy. A plane went in today to see if it could find a closed surface circulation because until this morning (or maybe it was last night) they said it didn’t have any. I am afraid my “Computer Says No” (hee hee, Little Britain ref) … I have been saving snapshots of the vorticity (circulation) over the past few days, showing quite clearly that it had good circulation in the lower half of the troposphere. Maybe it will be named for a couple of minutes, we’ll see.  

There is another Blob and also a Blobette out in the Atlantic:

The cloud that the NHC have marked with a 20% chance (yellow) of something developing currently has just a smidgen more convection than a desert on a dry day and the circulation is pretty weak and not well defined. The area where the NHC have a 30% chance (orange) of something developing just came off Africa and does actually have more circulation and convection, so I’ll agree with their assessment of that one for now. 

The next three names are: Harvey, Irene and Jose. Hmm. I know a Harvey, Irene and Jose.

(non-sequiter) <cheese break><yumyum> (end non-sequiter)

We are on Tropical Depression number 8, and have had 7 named storms so far. I believe this is the first year since satellite observations began in the 1970s that we have not had a hurricane in the first 7 named storms! I think there are a few reasons for this:
1. They are naming storms that, in the days of yore, wouldn’t be named Tropical Storms.
2. Satellites are picking up storms out in the Atlantic that we would not have detected otherwise because they would be short-lived or small.
3. There are factors that are inhibiting storms. We’ve seen these in other seasons – things like wind shear, cooler water temperatures, atmospheric dynamics etc. This year (so far) I think the most likely culprit is the dust in the Saharan Air Layer (SAL) that I mentioned a few days ago – lots and lots of that zero-calorie ;-) dry dusty air around. You can see an up-to-date map at and even watch a movie of the SAL over the past 5 days (ooh… who has the popcorn? ;-)).

These little tropical storms are useful things. For example, tropical storms account for at least 25% of Florida’s annual rainfall. We need them to bring some lovely rain and keep us out of drought conditions. It’s just when they get a bit too big for their boots that we get into trouble.

Time for another cheese break I think. J
Ciao (chow!) for 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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