Tropical Storm Isaac, Tropical Storm Captain Kirk, and Atlantic Blobette: August 29, Update A

Well things didn’t go quite as well as one could have hoped for on the northern Gulf coast today. Isaac decided to visit the area for a little longer than is decent really, and stalled for a few hours. I hear that although the levees and other flood-control devices (gates, pumps etc) around New Orleans held (the ones that were bolstered since Katrina – which was 7 years ago today), a levy in the outskirts (Plaquemines Parish) was overtopped with water about 14 feet above normal. There is, of course, a lot of flooding in other places along the Gulf coast. Here is a photo of east Biloxi, MS, (90/Beach Blvd) that I got via Andy F. (thanks!):

If Isaac had passed or stalled east of New Orleans, it would have been a different story because of the angle of the mouth of the Mississippi and the direction of winds. Here is the map of Louisiana from the tidesonline website:

The map is a reference as you look at these water level observations from Shell Beach and Berwick (I grabbed these around 2pm EST):

At Shell Beach (left), on the east side of the eye, the water reached a maximum of about 12 feet above normal.

However at Berwick (right), on the west side of the eye, water levels were approaching 4 feet below normal… combined, that’s a water level difference close to 16 feet between the east and west side of the eye! (thanks to Dennis M. for prompting this discussion earlier today!)  

 

Tropical Storm Isaac

He was downgraded from a hurricane this afternoon (around 2pm). He is now (finally) moving NW at an excruciatingly slow 5mph, and is currently at 30.1N, 91.1W. Central pressure is 977mb, winds are now 60mph. However his impact wasn’t so much in the winds (other than they caused the water to pile up) as it has been in the water and rain.  There are still some strong rain storms (as anyone in Alabama, Mississippi and half of Louisiana will tell us), but they are diminishing… not so much of the tornado-generating storms now, mostly heavy rain.

 

He is forecast to remain a Tropical Storm until he pretty much clears Louisiana, and will then be a tropical depression as he tracks north and then northeast though Arkansas, Missouri, Illinois, Indiana and Ohio. Quite a collection of states! It looks like his progress through Louisiana will be slow so I agree with the downgrade before he leaves the state. At the moment it looks to me like he doesn’t have a lot of room to move very far north and may just fizzle out in Arkansas. Perhaps this will change by the time I see the data tomorrow. The circulation is still very strong throughout the troposphere.

 

Tropical Storm Captain Kirk

Switching gears to the next one out there… we have Tropical Storm Kirk, that shall henceforth be known as Tropical Storm Captain Kirk. He is at 25.3N, 47.6W, heading WNW at 12 mph. Minimum pressure is estimated to be 1005mb, winds are estimated at 50mph, which makes him a weakish TS (range: 39-73mph).

 

The circulation is strong in the lower half of the troposphere but nothing much going on in the upper half (yet). There is not much wind shear but his convection is really pretty wimpy (not an adjective that macho Captain Kirk would approve of!) because he is being caught up in what is left of the dry Saharan Air Layer (SAL).

 

He is forecast to stay in the Atlantic… and boldly go where no man is (hahaha).

 

Atlantic Blobette

Hmm… this one may be one to watch. This blobette’s convection is bordering on the good side because she is on the very southern edge of the dry SAL. her circulation (vorticity) has slowly improved throughout the day, and there is even a signal in the upper troposphere which is a sign that she may blossom into a hurricane when she grows up.  Wind shear is weak, water temperatures are warm… things look good for intensification. Currently the NHC give her a 70% chance of developing into  a Tropical Storm in the next 48 hours… I think it may be sooner than that. She is around 12.5N, 40W, moving WNW at 15mph. I’ll have a look at her future path when she is a Tropical Depression or Storm. The next name is Leslie.

 

Good luck to everyone caught up in Isaac! If you get a chance, let me know how you fared!!

 

Adieu for today,

J.

 

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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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