Hurricane Dean brushed Category 5 status Saturday as the storm moved deeper into the Caribbean Sea. Dean, the fourth tropical storm of the 2007 Atlantic Hurricane Season and the first major hurricane of the season, experienced a round of rapid deepening Friday night, dropping 46 millibars of pressure from 5AM CDT Friday to 5AM CDT Saturday.
Hurricane Dean had a very tight eyewall early Saturday morning. However, later in the day, Dean began undergoing an eyewall replacement cycle as hurricane reconnaissance found concentric eyewalls, with the inner eyewall open to the south.
SSMI Satellite Image Category Four Hurricane Dean - Courtesty of NRL Monterrey
Hurricane Dean is likely to fluctuate in intensity, though should remain a category four hurricane continuing west-northwestward across the Caribbean Sea.
Forecast Models in considerably good agreement
Most of the forecast models, excluding the usually reliable GFDL are forecasting Hurricane Dean to move inland along the northern Mexico coast. The GFDL, as of the 7AM CDT run this Saturday morning, was forecasting Hurricane Dean to move inland just north of Brownsville. The concensus, which is agreed on by the National Hurricane Center, is for a general west-northwest track across the northern tip of the Yucatan Peninsula and then inland between Tampico and Matamoras Mexico. This track would keep most of south Texas out of danger with minor tropical storm force wind and maybe as much as 10 inches of rain presuming a landfall near Matamoras. A landfall further south would keep south Texas rather windless but could still see a few inches of rain primarily in the outlying feeder bands of the hurricane.
Hurricane Dean Forecast as of 5PM CDT Saturday - Courtesy of NRL Monterrey
GFDL Cause for Concern
The GFDL, which is considered a very reliable forecast model by most meteorlogists in this type of situation continues to want to bring Hurricane Dean into the lower Texas coast, about midway between Brownsville and Corpus Christi. This is a track which has shifted remarkably south over the last 24 hours as early Friday the GFDL wanted to drive Dean into deep southwest Louisiana.
Gulf Low at Stake
A Low Pressure system moving off Florida into the Gulf of Mexico will ultimately determine where Dean makes landfall. The low, visible on water vapor satellite imagery, will continue to progress westward across the Gulf and into Texas over the next several days. As the low moves west, high pressure will build in behind the low, thus keeping Hurricane Dean on it’s current forecasted track. However, if this low should slow or if Hurricane Dean should pick up speed in it’s forward movement, the odds will rise for a bit of a more northward track. The National Hurricane Center has requested the Gulfstream IV Reconnaissance Jet to fly two daily missions until landfall. The data this aircraft collects will be plugged into the computer systems and help the models get a better grip on the low, it’s movement, and the strength of the high building in behind it. This crucial data will help refine the forecasts and make sure those inevitably in the path of Dean can get the earliest possible warnings issued.
Hurricane Dean Water Vapor August 18, 2007 - Courtesy of Tropical RAMSDIS
Will Hurricane Dean survive the Yucatan
Hurricane Isidore in 2002 became a menacing category three hurricane as it moved across the Caribbean Sea. The storm was forecast to brush the tip of the Yucatan before moving north into Louisiana. However, Isidore took forecasters by surprise when it abruptly moved inland and remained over the Yucatan for almost 1 1/2 days. Isidore faded to a tropical storm before beginning its track north and never regained it’s hurricane status.
Hurricane Dean is not expected to make this same type of turn. However, it will be interesting to see the effects the Yucatan has on Dean as the hurricane passes. The interaction, regardless of where Dean strikes, could be enough to disrupt the storm and cause significant weakening.
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