Atlantic season's first storm slogs toward Houston

MIAMI, Florida (CNN) -- Allison, the season's first tropical storm, is dropping heavy rain in the Gulf of Mexico as it heads toward Houston, the National Weather Service said Tuesday.

Packing maximum sustained winds of 60 mph, Allison is expected to make landfall between midnight and 2 a.m. EDT Wednesday, causing a storm surge of 3 to 5 feet. Rainfall up to 5 inches is possible over much of southeast Texas and portions of Louisiana.

A tropical storm warning is in effect from Sargent, Texas, to Morgan City, Louisiana.

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At 5 p.m. EDT, Allison was about 35 miles south of the Houston-Galveston area, moving north at near 12 mph.

Flash flood warnings were issued from Houston to the Intercoastal City and northward to Lufkin, Texas.

The nation's forecasters say the June 1 to November 30 hurricane season should have the average of seven or eight hurricanes, and 11 named storms in all.

Last year there were 14 named storms.