MIAMI (AP) _ The Atlantic hurricane season's first tropical depression dissolved Thursday in the southwestern Gulf of Mexico after about a day.

An aircraft sent to investigate the depression in the Bay of Campeche found it had degenerated into a broad area of low pressure without defined circulation, said Lixion Avila, a hurricane specialist at the National Hurricane Center in suburban Miami.

He said the system will continue to be closely monitored for any signs of redevelopment and, if necessary, another reconnaissance plane will investigate on Friday, he said.

The central area of the low was found in the central part of the bay, with most of the associated showers and thunderstorms forming to the east. The low pressure is expected to drift west or northwest, toward northeast Mexico or southeast Texas, over the next two or three days, Avila said.

Tropical Depression One was born Wednesday and attained sustained winds of about 30 mph. Winds from the west prevented the storm from strengthening.

Tropical depressions become tropical storms once they reach 40 mph. Tropical storms become hurricanes once their top sustained winds reach 74 mph.

In 1999, there were 12 named storms and eight hurricanes, five of them major.

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On the Net:

National Hurricane Center: http://www.nhc.noaa.gov

Federal Emergency Management Agency: http://www.fema.gov

Red Cross disaster guide:

http://redcross.org/disaster/safety/guide/hurricane.html