41 Deaths, $9 Billion in Damage: The Legacy of Tropical Storm Allison

Every June, meteorologists and emergency managers along the Texas Gulf Coast mark an anniversary that most Americans outside the region have long forgotten. In June 2001, a tropical storm that never reached hurricane strength caused more damage and death than most hurricanes ever do — and permanently changed the way the city of Houston thinks about rain.

Tropical Storm Allison made landfall near Freeport, Texas on June 5, 2001. It was, by almost any measure, a modest storm. Its winds never exceeded 60 miles per hour. It spent less than a day over open water before coming ashore. In the conventional sense of what makes a tropical system dangerous, Allison barely registered.

What it did with rainfall was another matter entirely.

Forty Inches in Five Days