Tuesday, August 21, 2012

Charleston, Myrtle Beach Devastated by Isaac in GFS Individual Ensemble Forecast

A member of the 12z GFS Ensembles is showing a solution that would devastate Myrtle Beach and Charleston. This member shows a very strong hurricane slamming into the Southeast and possibly providing mass flooding and a preceding mass exodus, should this threat become real.

However, realistically, this possibility is very very low. That's why we also have a mean forecast of these individual ensemble forecasts. This is more of a for-show piece, but also demonstrates the potential that Isaac now has, and just what it ends up doing is very uncertain after what the ECMWF put out today, and that is shown below.

At Hour 240, the ECMWF is projecting a 961mb hurricane moving towards the Gulf Coast. Because rapid intensification will have been ongoing to this point, it is very possible that such intensification continues. From then, landfall could likely occur from Louisiana eastward. The ECMWF Ensembles are not as eager, but do show a system entering the Gulf of Mexico, and this could very well get aggressive very, very fast.

More on this will be available tomorrow.


BREAKING: Tropical Storm Isaac Forms

Reconnaissance data from aircraft investigating Tropical Depression NINE have sent back information that shows many instances of tropical storm winds being observed, including one wind speed calculated at 44 MPH.

This means that the next National Hurricane Center update will most likely certify this as Tropical Storm Isaac. I will have an evening post up and out later on.


BREAKING: ECMWF Bombs TD-NINE Into Major Hurricane in Gulf of Mexico

The fresh-off-the-presses 12z ECMWF has shown a Category 3 major hurricane swirling in the Gulf of Mexico, with a central pressure of 961 millibars- and it's still offshore.
This comes as the models begin to split up on a solution. Now that the ECMWF is sending a major hurricane into the Gulf of Mexico, time will only tell how the next model suite reacts to this news.


Tropical Depression NINE Forms in Atlantic

Tropical Depression NINE has formed this morning over the Atlantic out of Invest 94, beginning the process that could land this system anywhere from Texas to Nova Scotia at any strength you can think of. Below is the latest model spread.

The latest 12z model spread is split, but a general consensus keeps the system going on a mainly westward track before curving north and threatening Florida. Which side it threatens remains a question, and that will largely depend on how weak/strong it becomes over the next 24-48 hours. Let's look at the observed track to see recent trends.

The latest trend in Tropical Depression NINE's track is a west-southwest movement, which bodes well for a threat to the Gulf Coast. Now, this threat is not too great to begin with (unless a southwest motion begins), but a Florida threat increases with every motion to the west or west-southwest. Typically, systems above the 10 N line will recurve and go either out to sea or threaten the East Coast. Whether that happens remains to be seen.


Past track and forecast tracks from UW-Milwaukee