Monday, August 16, 2010

Northern Gulf Blob formerly known as TD5: August 16, Update A

Huh. I'm pretty sure that by the official definition of 'Tropical Depression', this blob is a Tropical Depression (TD). When I say "official definition", I don't mean *my* official definition which, of course, is always correct (in my world anyway). ;-) I mean the actual official official definition of a Tropical Depression - a closed circulation with winds below 39 mph.
It clearly has a closed circulation, as seen in satellite images and also as found by a plane that was sent to investigate the system this afternoon (from the NHC: "AN AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT INVESTIGATING THE REMNANTS OF TROPICAL DEPRESSION FIVE FOUND A WEAK SURFACE CIRCULATION LOCATED ABOUT 120 MILES EAST OF THE MOUTH OF THE MISSISSIPPI RIVER").  Winds from surface buoy observations in the area are at a maximum of 21 mph. Drawing upon my vast scientific knowledge, I can tell you with 99.99% certainty that 21 is less than 39! ;-) I reckon it's a TD. 
The vorticity (circulation) is pretty good in the lowest half of the atmosphere. The convection now extends into Texas, even though the center of circulation is just south of Alabama. It looks like it is moving WNW, towards the Mississippi/Louisiana area.
There are three things that are keeping this blob on the weaker end of the spectrum: it is interacting with land, the warm water is very shallow, and there is some decent wind shear, which means the convection is mostly to the south and west of the center of circulation. So, even though I think this is a TD, I am not sure it will get to Tropical Storm status (winds greater than 39 mph) because of these factors.
If you suffer from sea-sickness, I don't recommend going out on the Gulf any time soon. Waters have been a bit on the 'oh yeah, that's what I had for lunch' side in the Gulf, with reports of 9 ft plus seas (thanks for the note Gene S.). It might be good for you surfers - but I expect your surf-dar already told you that and you are all out there and not reading this anyway! :-) Water levels along the coast aren't too high - about 1ft above normal in the Mississippi area. 
That's all I got... until 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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