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Dean reaches hurricane strength

Tropical Storm Erin came ashore in Texas today bringing heavy rain to an area that has already been inundated this summer. At the time she came ashore, Erin was only a minimal tropical storm so damage was limited. Currently she is spinning onshore and slowing decaying.

Further out to sea, Dean has continued to further organize and strengthen. Dean has been steadily intensifying and is now a category 1 hurricane with maximum sustained winds of 90 mph with a central pressure of 979 mb. This intensity is somewhat uncertain and a hurricane hunter will investigate the system later today. Dean has been very slow to strengthen, but has steadily done so, especially during the night. Dean is a very small and compact storm, which should limit the lateral extent of the damage but also will allow for much more rapid intensification. There seems to be nothing to limit the intensity of Dean, so strengthening to a major hurricane is expected.

Interests in the Caribbean should pay close attention to Dean as he is likely to become a very dangerous hurricane heading their way. Microwave passes have consistently revealed a partial eyewall structure for over a day. More recently, an eye has been intermittently visible in geostationary infrared imagery, and a small clouded over eye is visible in water vapor imagery. Such a small eye is what we often see in rapidly intensifying super-storms like Wilma just before they pop.

Since Dean is rapidly approaching the Caribbean, Hurricane Warnings and a potpourri of other advisories have been issued for much of the eastern Caribbean. See the map below for details.

As a fair warning, the models have been showing surprisingly strong agreement in forecast Dean to progress to the west and steadily intensify to a major hurricane. Shear has been limiting the systems development but is lifting and will continue to do so. I am forecasting Dean to steadily strengthen into a major hurricane as it moves toward the Caribbean. Sea surface temperatures (SSTs) only get warmer in the Caribbean and could lead to further strengthening. The western Caribbean especially is primed for a major hurricane. With this said, the eastern Caribbean is often a tough place for storms to thrive given historically higher wind shear and synoptic scale subsidence due to convection over South America.

The models are in strong agreement in tracking Dean westward across the Caribbean, near Jamaica and the Caymans, and toward the Yucatan. I have no reason to doubt these forecasts and see no steering currents that are likely to recurve the storm toward the US. However, I will continue to monitor the storm for changes. Below are the model forecast charts which will automatically update:

Posted by Bryan Woods | Permalink