Tropical Storm Allison

Southern United States, June 4–18, 2001 

The first named tropical cyclone of the 2001 North Atlantic hurricane season, Tropical Storm Allison delivered deluging rains to portions of southeastern Texas and Louisiana between June 5 and 11, 2001. Allison dropped between 10 inches (250 mm) and 30 inches (760 mm) of rain, claiming 24 lives and causing more than $5 billion in property losses.

The most costly tropical storm yet recorded in the United States, Tropical Storm Allison developed in the Gulf of Mexico on June 4, 2001, from a subtropical low pressure system that had originated over Mexico’s Bay of Campeche. On June 5, five days after the official start of the 2001 hurricane season and as the system meandered some 130 miles (200 km) south of Galveston, Texas, the National Hurricane Center (NHC) upgraded the system to tropical storm status, awarding it the name Allison. Carried westward, Allison’s sustained 60-MPH (95-km/h) winds and heavy rains came ashore at Freeport, Texas, during the midafternoon hours of June 5. Bearing a central pressure of 29.52 inches (1,000 mb) and surging rains,

Allison’s poorly organized circulation system traveled slowly over northern Texas, then, on June 8, drifted southward, bringing enormous precipitation counts to the Houston metropolitan area. In the Port of Houston, one of the nation’s busiest maritime trade nodes, some 37 inches (940 mm) of rain was recorded during Allison’s erratic passage inland. By June 9, streams and drainage canals across eastern Texas were quickly overflowing their banks, and large sections of downtown Houston— including its city hall—were flooded when the Buffalo and White Oak bayous became saturated.

Several medical facilities associated with the Texas Medical Center were evacuated as flash flooding caused by Allison’s record-setting rainfalls disrupted utilities and destroyed medical equipment. In some instances, Allison’s powerful downpours hampered the evacuations as they closed major arteries and freeways in the city. Some 70,000 residential and commercial structures in and around the Houston area experienced partial or total flooding, while in an underground parking garage in Houston, a woman drowned while trying to retrieve her automobile. All told, 21 people died in Houston, making Allison one of the deadliest tropical cyclones to have affected Texas in over a decade.