First U.S. hurricane warnings issued for Isaac

Isaac did not end up reaching hurricane intensity prior to making landfall on the southwestern peninsula of Haiti, but was intensifying as it came ashore at around 2am EDT this morning.  The peninsula is very mountainous, but also very thin, so Isaac's core only remained over land for about 3 hours, and is now back over water (Windward Passage) before it makes another brief landfall on Cuba's southeastern coast shortly.  You can follow this from the Gran Piedra radar loop (and others later).

At 8am EDT, the center was located in the Windward Passage, about 95 miles east-southeast of Guantanamo, Cuba.  I marked the center with a red L here, and you can see that the storm is still pretty lopsided, and that there's a disturbance to its northwest affecting southern Florida and the western Bahamas... BEFORE Isaac even arrives tomorrow into Monday.  As of 8am, the maximum sustained winds are 60mph, it's heading northwest at 14mph, and tropical storm force winds extend an impressive 230 miles from the center.

Since the track will end up involving relatively limited time over land, that gives the storm longer than anticipated to intensify prior to reaching southern Florida.  As such, hurricane watches and warnings are now in effect for Andros Island in the Bahamas, as well as all of southern Florida.  In this graphic below, hurricane warnings are red, hurricane watches are pink, tropical storm warnings are blue, and tropical storm watches are yellow.  If you're new to the lingo, here are the definitions from the NHC:

A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA. A WARNING IS TYPICALLY ISSUED 36 HOURS BEFORE THE ANTICIPATED FIRST OCCURRENCE OF TROPICAL STORM FORCE WINDS...CONDITIONS THAT MAKE OUTSIDE PREPARATIONS DIFFICULT OR DANGEROUS. PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE RUSHED TO COMPLETION.

A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA...IN THIS CASE WITHIN THE NEXT 24 TO 36 HOURS.

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

For the most recent rack forecast, watches, and warnings, visit the NHC website.

The probability of tropical storm force winds over the next 5 days is shown here.  Specifically, here's a table showing the probability of each wind intensity for some select cities (these will evolve as the storm approaches):

                 TS    HURR

----------------------------

MIAMI         |  67  |   4

KEY WEST      |  72  |  16        

FORT MYERS    |  68  |   9

TAMPA         |  57  |   5

APALACHICOLA  |  64  |  11

The other big issue will be the rain.  The following storm-total rainfall forecast spans 3 days, so some places will get their rain before it even starts in others.  Totals along the northern Gulf coast will be much higher, and will be included in future versions of the graphic.

Just for completeness, the disturbance in the far eastern Atlantic is not yet getting organized, and is now a couple hundred miles west of the Cape Verde islands.

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