After watching Hurricane Dean all week, Hurricane Dean has strengthened significantly today. As of the 11pm advisory Dean has 145 mph winds and a 937mb central pressure. Models and the NHC forecast continued strengthening over the next 24 hours. No matter how you slice it an extremely dangerous storm.
Currently the model consensus has Dean passing directly over Jamaica. Several things should be noted. If the eye of Hurricane Dean does pass directly over Jamaica, the high elevations of Jamaica should disrupt the storm significantly. Simiarly, if the eye passes near enough to Jamaica the mountainous terrain will likewise disrupt Dean, the question is how much of an impact the mountains will have.
All that said, it will be interesting to see how accurate the models are. Given that we are still around 40 hours away from a potential Jamaica impact, much can changed based on the speed that Dean continues to move westward. Dean’s westward speed will determine how much various features (e.g. the high over the SE US right now) move Hurricane Dean around. A slowing Dean (now 18 mph speed) will probably lead to a more southerly track whereas a faster moving Dean would lead to a more northerly track the farther out you go.
Up to 72 hours models are generally pretty accurate (some exceptions such as Hurricane Erin in 1995 when bad data was entered) so take precautions now. For more than 48 hours, everyone from Florida, through the Gulf Coast down to Central America should watch this storm and be prepared to take action as directed by local authorities. As you can see (as of 11pm, August 17, 2007), the NHC has a large area still in the 5% Tropical Storm Force Wind Speed Probabilities.
Preparation is key.