Tropical Storm Allison brought intense rainfall to the Gulf of Mexico states of Texas, Louisiana, and Mississippi. The first storm of the 2001 Atlantic hurricane season, Allison lasted an unusually long time, remaining a tropical or subtropical storm for 15 days. Allison reached Tropical Storm strength at 1200 UTC on June 5 with peak winds of 60 mph. Later in the day, Allison made landfall near Galveston, Texas with peak winds of 50 mph. Inland, the storm rapidly weakened with the National Hurricane Center discontinuing advisories early on June 6. From the NOAA Service Assessment, “Allison drifted back into the Gulf of Mexico on June 9, turned to the northeast, and made landfall again on June 10 near Morgan City, Louisiana. After causing 24 deaths in Texas and Louisiana, Allison moved across southern Mississippi, southern Alabama, southwest Georgia, and northern Florida, causing nine more deaths.”
Tropical Storm Allison caused more damage than any tropical storm in U.S. history, with estimates of more than $5 billion. Because of this, the name Allison was retired from being used by the National Hurricane Center. Allison became the only Atlantic tropical storm to have its name retired without reaching hurricane strength. In 2015, Tropical Storm Erika joined this exclusive list.
Most of the damage and fatalities (22) occurred in Houston, Texas.
In Louisiana, Allison ranks among the worst storms to hit the state in the past 100 years. The most significant flooding occurred on June 6-7. Much of the city of Thibodaux was flooded when 15.16 inches of rain fell in 24 hours. In East Baton Rouge Parish, flooding resulted in the evacuation of 1,800 residents and flooded 1,000 homes. Over 2,000 homes were flooded in Livingston, Lafourche, St. Tammany, and Ascension Parishes.
“By mid-week, Allison stalled over North Carolina and produced more heavy rainfall and flooding before tracking northeast along the Delmarva Peninsula and moving off the New England coast on June 18. Seven additional deaths occurred in Pennsylvania and one in Virginia.”
Within weeks of this storm, 75 counties in Texas, southern Louisiana, southern Mississippi, northwest Florida, and southeastern Pennsylvania were declared disaster areas by President George Bush.