Tropical Storm Andrea Forms in Gulf of Mexico [1]

Wunderground.com - 6/5/13, Dr. Jeff Masters

The Atlantic has its first named storm of the 2013 hurricane season: Tropical Storm Andrea [2]. An Air Force hurricane hunter plane was able to locate a closed center of circulation, and found surface winds of 40 mph in the large area of thunderstorms on the east side of the center. Satellite loops [3] show that Andrea is a lopsided storm. It's center of circulation is exposed to view, due to a large region of dry air that covers the entire Central and Western Gulf of Mexico. This dry air is from a trough of low pressure whose upper level winds are also creating moderate wind shear [4] of 15 - 20 knots over Andrea. Wind shear is forecast [5] to rise to the high range, 20 - 40 knots, by Thursday. Andrea is forecast to make landfall along the northern Gulf Coast of Florida by Thursday evening, so the system has a short window of time to intensify. Given the large amount of dry air to Andrea's west, and the forecast for increasing shear up until landfall, I expect that the strongest sustained winds Andrea could have before landfall are 50 mph. Heavy rains will be the storm's main threat, though a few isolated EF-0 tornadoes will also be possible in some of the heavier thunderstorms in Andrea's spiral bands. A storm surge of 2 - 4 feet is predicted for Tampa Bay northward to Apalachicola, and rip currents will be a risk for swimmers who brave the high surf. Fort Pickens, located in Gulf Islands National Seashore on a barrier island offshore from Pensacola, Florida, has been closed to visitors due to the approaching storm. A single 2-lane road vulnerable to storm surges runs to Fort Pickens. Officials want to prevent a repeat of the situation that occurred in September 2011, when Tropical Storm Lee pushed a storm surge over the road that blocked it with sand and debris, trapping numerous campers and visitors in Fort Pickens. As of 7 pm EDT, our wundermap with the storm surge layer turned on [6] was showing storm surge levels were less than 1 foot along the Florida coast.

For more information on this story please see Wunderblog.com [7]