Isaac Update

Tropical Storm Isaac is showing some organization this evening. Pressures have fallen a little since late afternoon and the deep clouds (dark red) are becoming more extensive.

A hurricane warning is in effect for Haiti and a hurricane watch is in effect for southeast Cuba including the Guantanamo Naval Base.  They are at the lower right portion of the image.

"Isaac's Path" refers to the location of the center, not necessarily the
geographic extent of the winds.  

Now, the bad news: I believe a hurricane will come ashore in the U.S. The question now is where and how strong it will be.

On the east side, it seems unlikely that the center would make landfall north of West Palm Beach. I have been a bit farther west than some of the other forecasters and I now have the west edge of my forecast on the Texas side of the mouth of the Sabine River.

Unless it makes landfall over the south part of the Florida Peninsula, it looks like Isaac will move across the extremely warm water over the Gulf. Given the light wind shear (little change in wind speed with height or direction) major and rapid strengthening should occur. If landfall occurs west of Apalachicola there is a real chance that a major hurricane (category 3-4-5) will develop.

I can't over-urge readers in the threatened area to consider preliminary hurricane precautions. I'm repeating some tips below.

NOAA and the U.S. Air Force are doing special data gathering this evening. The suite of data will go into tonight's computer models and will become available between about midnight and 3am CDT. So, when I get up in the morning, I'll post again with -- hopefully -- a narrower threat area.

ADDITION 7:50pm:
Courtesy of Jim Cantore, here is the path of the NOAA Gulfstream's data gathering mission this evening. They will drop a canister of weather instruments (a "dropsonde") in each of the numbered locations.

-- Some preliminary precautions below --

There are plenty of hurricane preparedness references on the web, including a number on this blog. Go ahead and start. If they turn out not to be necessary fine, no harm done. But, considering we have a weekend coming up, things like prescription refills*, a hurricane evacuation kit, roadmap (for an evacuation), etc., will be needed eventually, hurricane or not. Go ahead and get those low-cost but time-dependent items done soon. You'll have peace of mind and you and your family will be ahead of the game if a hurricane threat develops. 

* I almost forgot. During Irene last year, someone asked me why I always mention refilling a prescription in these early cautionary posts. Here's why..

Suppose you have twelve days ( = 12 pills) of Acme Wonder Drug in the bottle. Plenty, right? Wrong!  

Assume you, your pharmacist, and physician live in Mosquito Junction By-The-Sea. An evacuation is ordered Sunday afternoon (you are down to eight pills) for a storm predicted to strike Mosquito Junction By-The-Sea on Tuesday (down to six pills). Further assume that, unfortunately, weather science is correct as usual. The National Guard comes in and ropes off Mosquito Junction for a week (which is common). You are down to a single pill.  

Given that you are in a motel in Hogwash Falls waiting to return home and your physician and pharmacist are in the same boat, how are you going to get that prescription refilled? So, you want to make sure you have plenty of prescription medicine and other critical supplies before an evacuation order might be issued.