Sunday, August 26, 2012

Isaac Is Now In The Gulf

Key West is normally a festive place particularly leading up to Labor Day.  Tonight it is a different place.  Webcams show only a few cars on the road on only a few brave souls on the streets.  Any partying is being done indoors.  It has been a rainy and windy day in Key West with gusts frequently up to 40 mph.  Peak gust occurred at 1:22 p.m. with winds to 47 mph.

Image from a webcam in Key West, FL.  Image Credit:

Isaac took a turn to the west-northwest for much of the day taking it through the Florida Straits.  It passed south of Key West late this afternoon instead of going through the Keys.  At 8 p.m. EDT on Sunday, the storm was located about 60 miles southwest of Key West moving west-northwest at 15 mph.  Maximum sustained winds were about 65 mph making it a tropical storm.

Key West radar as of 8 p.m. EDT August 26, 2012.  Image Credit: NOAA/NWS.

Dry air has been moving into the storm from the southwest for most of the day.  However, tonight it appears that a central dense overcast is forming over or near the storm's center.  The National Hurricane Center has noted a slight increase in the winds.  A gradual strengthening is expected until Isaac makes landfall late Tuesday or early Wednesday.

Enhanced satellite picture using the water vapor channel.  Image Credit: NESDIS.

This afternoon many of the computer simulations used to forecast the storm’s future were shifting the track farther west.  A couple of simulations not shown below were still forecasting the system to make landfall in the Florida panhandle.

Computer simulations of Isaac's future path initialized from the 18z data.  Image Credit: NCAR.

The spread in the simulations has left the forecasters at the National Hurricane Center little choice but to warn a large area of the coast.  Hurricane warnings were in effect from east of Morgan City, LA, to Destin, FL with a hurricane watch to Indian Pass, FL.

Isaac forecast from the National Hurricane Center as of 8 pm EDT August 26, 2012.

A broad trough in the upper atmosphere is forecast to dip south into the eastern part of the country over the next few days.  This will create a weakness in the subtropical ridge with centers near Bermuda and over Colorado.  The storm should turn northward in response to this and make landfall somewhere between Panama City, FL, and New Orleans, LA.

I confess that I am leaning more to the ECMWF simulation even though many of the ensemble simulations have the storm near New Orleans at landfall.  Isaac has managed to surprise forecasters at times.  However, the National Hurricane Center forecasters have done a fine job with a difficult storm.

The story of Isaac will not end with landfall.  All of the simulations show that the trough will not steer the storm to the northeast.  Instead it will be left behind to drift slowly northward as a tropical rainstorm.  This may bring another legacy to this storm in the form of flooding rainfall into the Labor Day weekend.  Isaac may still have life for some time to come.