Tropical Update: Ana Ailing, Bill Blossoming

* Heat Continues: Full Forecast | Hurricane Tracking Center *

By Dr. Greg Postel, Hurricane Expert

*11 a.m. update: Hurricane Bill continues strengthening. Max winds up to 90 mph.

Satellite image of Tropical Depression Ana. Courtesy NOAA.

When storms develop in the tropics, they often do in bunches. Indeed, multiple storm 'genesis' events occurred almost simultaneously over the weekend when three storms developed in a mere 33 hours. (I believe the Madden Julian Oscilliation has something to do with this, and I'll write more on this in another post). Even with Claudette having washed ashore the Florida panhandle last night, the tropics are still giving us two systems to monitor.

Tropical Depression Ana is a very small, rapidly moving, and disorganized system about 70 miles south of St. Croix. Though the shear -- which tends to tear storms apart -- is low (for now) and the ocean water sufficiently warm, the surrounding air has been quite dry, inhibiting its growth. Ana's small size will render it highly susceptible to environmental conditions. As Ana is likely to interact with the hostile terrain of the Dominican Republic, Ana may quickly dissipate into nothing more than an eddy. If it survives the island tour, it may re-emerge over the eastern Gulf of Mexico and find conditions more conducive for growth. Ana's projected path ultimately steers it towards Florida or the Gulf coast, so it continues to bear watching.

Keep reading for the latest on now Hurricane Bill...

Bill, upgraded to a hurricane (maximum sustained winds are now at 75 mph) this morning, is by far the largest of the storms to form this season. Located over the central tropical Atlantic, it had previously exhibited an asymmetric presentation in the satellite images, suggesting the nearby presence of a Saharan air layer. Last night, however, the storm seemed to overcome the surrounding dry air (shaded in red in the image below) and is appearing much better organized.

Hurricane Bill early this morning. Courtesy University of Wisconsin Space Science and Engineering Center

Many of the models (including the official National Hurricane Center guidance) are forecasting Bill to become a major hurricane in the next several days. Though Bill may very well reach Category 3 (or higher) status, nearly all of the models are predicting that it will recurve out to sea and not impact the mainland United States.

But we'll keep you posted as this storms continues westward over the next several days.