Saturday, August 25, 2012

Isaac Threatening Florida; Hurricane Warnings Hoisted

Watches and warnings line the northern Caribbean and eastern Gulf Coast this morning, as Isaac leaves Haiti to continue towards the Gulf of Mexico.

Hurricane warnings have been hoisted in the face of Isaac in Florida, as well as tropical storm warnings blanketing Cuba. Isaac has just moved off of Haiti and appears to be heading northwest, towards the Florida Keys and the Gulf of Mexico.
If Isaac makes landfall on Cuba, it appears to be brief, and only a slight change in storm strength would likely be observed. However, if Isaac plows into Cuba, which is unlikely, the tropical storm could have issues with keeping itself together.

The latest Advanced Dvorak Technique (ADT) placement of the center puts Isaac at about 19 N longitude and 74 W latitude. This indicates Isaac has been moving northwest in the past while, but the first NHC graphic appears to show a west-northwest tilt as of the current center.
From this viewpoint, it seems a brief landfall on Cuba is likely, but nothing major as far as going through much of the country.

The forecast from the National Hurricane Center takes Isaac on a northwest path into the Florida Keys before curving north and making landfall on the Florida Panhandle. This does appear to be a fair track, but any wobble in any direction could drastically change the outcome of the track of Isaac. I am looking for hurricane warnings to be spread out across western Florida, the Panhandle, and Mississippi's into Alabama's portions of the Gulf Coast when Isaac nears.

The spread of models appears to be wanting to take Isaac a bit further west, possibly into Alabama or the extreme western Florida Panhandle. Considering the Southern US has been launching special radiosondes at 6z and 18z to aid the models in tracking Isaac, I would expect this to be a good consensus. However, it looks like a few models remain unsure, even 24 hours out, on where Isaac will be.

Intensity forecasts are also very scattered, but seem to have an idea of Category 1 hurricane strength in the next 3-4 days, before making landfall and weakening and possibly degenerating into an extratropical low. After that, some models project Isaac will shoot out to sea.

Storm surge is a big concern. The NHC is projecting that there is anywhere from a 0-30% chance of storm surge levels reaching 5 feet in Florida. The values appear to be so low because of no clear model consensus, but this remains a threat either way. Such a large storm has the potential to produce a very large storm surge area, possibly well inland of western Florida.

Andrew

4 comments:

Indndawg said...

THE LOW-LEVEL CENTER HAS JOGGED WESTWARD DURING THE PAST FEW
HOURS...AND THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 315/15. IN
THE SHORT-TERM...A MID/UPPER-LEVEL TROUGH OVER THE EASTERN UNITED
STATES IS LIFTING OUT TO THE NORTHEAST AS A UPPER-LEVEL LOW MOVES
SOUTHWARD ACROSS THE CENTRAL GULF OF MEXICO. THIS EVOLUTION...
COMBINED WITH THE LOW-LEVEL RIDGE NORTH OF ISAAC..


As you predicted. Still looking for landfall MS/AL.

ERN WX said...

Andrew, great work with this storm. It clearly doesn't want to go N right now. I'm thinking a cat 2or 3 at landfall. Ouch. Folks, this one is going to hurt.

Anonymous said...

andrew todays 12z run of the euro has pressure of isaac at 954 mb how strong would the winds be

Andrew said...

ERN WX: I agree with your strength thoughts. It's great having your input on the storm.

Anonymous: It is very difficult to put pressure and winds together, so I cannot confidently say.