Saturday, August 25, 2012

Isaac to Become a Hurricane Tomorrow; A Double U.S. Landfall Possible Next Week...

The center of Tropical Storm Isaac largely passed to the West or Southwest of the most rugged terrain of Hispaniola overnight, which has left the system largely intact with little change in intensity.

As of 8am EDT this morning, the center of Isaac was located 95 miles East/Southeast of Guantanamo, Cuba, and was moving toward the Northwest at 14 mph.  Maximum sustained winds are estimated at 60 mph, and the minimum central barometric pressure is 29.47 inches of mercury.

The center of Isaac is forecast to move across the Eastern tip of Cuba later today, and will have minimal interaction with land once again.  This will allow the system to intensify rather quickly once it emerges back out over open waters on Sunday, with hurricane force winds likely by the end of the day.

Computer forecast model consensus has shifted slightly toward the East since my post yesterday morning.  Most of the models now call for a U.S. landfall in the Florida Keys, as a hurricane during the pre-dawn hours Monday, followed by a second landfall (as an even stronger hurricane) along the coast of the Florida panhandle during the pre-dawn hours of Wednesday:

The latest National Hurricane Center (NHC) track lies down the middle of the model forecasts, as shown on the image below:

It is noteworthy that the U.S. GFS model is calling for a track more toward the Eastern edge of the white "cone" on the above image, while the European (ECMWF) model is calling for a track along the Western edge of the cone.  The key element with the track beyond Monday will be the interaction of the system with a developing trough of low pressure over the Eastern U.S.  Until that interaction becomes more clear, it is difficult to say exactly where Isaac will track within the white cone on the image above.

Due to the uncertainty of the exact track of the system beyond Monday, and because the effects of Isaac will be felt well away from the exact location of the center of the system, I continue to highly encourage all residents along the Gulf Coast from southeast Louisiana through Florida to complete their hurricane preparedness activities this weekend.

One thing is for sure, Isaac will strengthen quite rapidly once it enters the warm, undisturbed waters of the Florida Straits and then the Gulf of Mexico.  I encourage those in the path of the second landfall to prepare as if Isaac will be a major hurricane, as this is certainly a possibility.   I would rather see folks "over prepare" and cover all of their bases than be caught off guard at the last minute.

Heavy rainfall will be widespread in association with Isaac.  Rainfall totals in excess of 6 inches can be expected across southern Florida and the Keys:

There will also be an increasing threat of tornadoes in southern Florida in association with thunderstorm activity on Sunday and Monday.

For the latest imagery and updates on Isaac, please refer to this dedicated webpage at our sister site,  Now that the system is threatening the U.S. in the near term, I'll be posting more frequent updates here on the blog.  I will also post various shorter updates with additional images, etc., on both facebook and twitter.  If you would like to receive those updates, please be sure to follow me there if you aren't already:

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