TS Dean path unsure

Tropical Depression 4 upgraded to Tropical Storm Dean in the Atlantic Ocean on Tuesday morning.

Although the consensus path of NOAA’s National Hurricane Center forecasts the storm to turn northward toward Puerto Rico, one major computer model – that of the UK Met Office – forecasts Dean to continue westward and enter the Caribbean Sea.

Tropical Storm Dean

This image provided by NOAA Tuesday, Aug. 14, 2007 shows the position of the Tropical Depression that has formed into Tropical Storm Dean, bottom right, at 7:45 a.m. EDT. Tropical Storm Dean formed in the open Atlantic on Tuesday, but remained far from land, forecasters said. At 11 a.m. EDT, the storm was centered about 1490 miles east of the Lesser Antilles in the Caribbean.

The UK Met Office’s computer was the only major model to accurately forecast in September 2004 that Hurricane Ivan would continue westward toward Grand Cayman instead of turning northward as all the other major models predicted.

The uncertainly lies – as it did with Ivan – with a high pressure ridge that is expected to build north of the storm. If it strong enough, it could push Dean westward toward Cayman and then possibly into the Gulf of Mexico.

In its forecast discussion, NOAA stated Dean should continue moving generally westward through Wednesday or Thursday.

‘Thereafter, the forecast becomes highly uncertain since some reliable models maintain a strong ridge to the north and keep the cyclone moving westward across the Caribbean, and others show a weaker ridge resulting in a gradual turn to the west-northwest.’

As of 10 am Cayman time Tuesday, the storm was 1,490 miles east of the Lesser Antilles. It was moving at 23 miles per hour, but was expected to slow down gradually. Top winds were 40 miles per hour.

Dean is expected to become a hurricane sometime Thursday evening or Friday morning and then intensify to near major hurricane strength – with winds close to 110 mph – by Sunday morning.

If Dean did follow a westerly track into the Caribbean Sea, it would likely come closest to Cayman late next week.

Historically, there was one other August tropical storm located within 400 miles of Dean’s present position that impacted the Cayman Islands. That storm, an unnamed major hurricane in 1903, is one of only three tropical cyclones thought to have brought winds of more than 100 mph to Grand Cayman. The other two were Hurricane Gilbert in 1988 and Hurricane Ivan.

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