First hurricane of the season

At the 5 AM advisory this morning, the Hurricane Center upgraded Dean to a hurricane, making it the first one of the season. He is a minimal hurricane, with 75 MPH winds, and is moving toward the west at 24 MPH. Hurricane warnings have been hoisted for the islands of Dominica and St. Lucia, and a variety of other watches and warnings have been issued for most of the remaining Lesser Antilles. Hurricane conditions are expected in the warned area within 24 hours. The Hurricane Hunters are planning to fly into Dean today.

Taking the longer term view, the modeling of Dean's future track remains in excellent agreement. None of the models track Dean north of Jamaica, and many of them move him into the Yucatan at day 5. In other words, they're all rather far south of Florida. This, of course, is subject to change. In fact, there could be a bit of model gymnastics (flipping and flopping) by this time tomorrow; in addition to the Hurricane Hunter mission, NOAA is planning to fly an environmental weather data sampling mission tonight to provide additional observations for input to the models. Model accuracy typically increases when these data are ingested, and occasionally we see some, ahem, interesting changes in the track.

The primary features governing the steering currents are a dome of high pressure directly to the north of the storm, and an area of low pressure over the Bahamas. You can see these features in this water vapor satellite loop (warning: link is not safe for dial up). Both of these features are forecast to move toward the west, such that the low would not pull Dean to the north while the high pressure dome would persist the westerly track into Mexico. The sampling mission tonight is designed to provide data to more accurately describe these features. If the low doesn't move as expected, the western Gulf of Mexico coast comes back into play early next week.

Intensity forecast remains straightforward. Based on our current knowledge of hurricane intensity change (which, admittedly, at times doesn't seem like we know very much) there appears to be little reason for Dean not to intensify over the next 5 days. No interactions with land or wind shear are expected, and the ocean temps are warm. Forecast to major hurricane strength is expected.

Tropical storm Erin is forecast to move onto the Texas coast sometime in the next 12 hours. Biggest threat is flooding from the 3-6 inches of rain expected there. This is a part of the country that does not need additional rain. If the current modeling is to believed, this area may get another dose of tropical rain next week.