This is what happened when Tropical Storm Allison hit Houston area 19 years ago

HOUSTON – Nineteen years ago, Tropical Storm Allison made landfall and left Houston underwater. Allison delivered the most devastating rain Houston had ever seen.

Tropical Storm Allison started as a disturbance in the Gulf of Mexico in June 2001. No one expected it would end up going on record as one of the most devastating rain events in U.S. history.

In just days, the storm dumped 80% of the area's average rainfall.

Two million people were affected. Most of the deaths occurred from people walking or drowning in high water.

The National Weather Service issued a Flash Flood Warning three hours before the first fatality, and five hours before the first drowning.

When Allison was finally finished, 41 people were killed across the country, 95,000 cars were flooded and 73,000 homes were damaged. More than 30,000 people were left stranded in shelters and $5 billion in damage was done to property. Greens Bayou saw 27 inches of rain and other places experienced even more flooding.

The storm also destroyed 25 years of research at the Texas Medical Center.

Locally, 18 people drowned and three people were electrocuted. Death and destruction were everywhere.

Allison is the first tropical storm to ever have its name retired, alongside hurricanes like Katrina, Rita and Ike.

Allison's slow and erratic progress moving inland and back out to the Gulf set it apart from every storm to hit Texas in the past century.

An analysis was later done on the path of Allison as it became a storm to remember.

The storm actually began as a Tropical Wave off Africa on May 21, 2001. Within five days, it had traveled west and over northern South America before continuing west across Central America and into the eastern Pacific on June 1. By June 4, it had moved into the Bay of Campeche and toward Galveston where, by the afternoon of June 5, it officially became Tropical Storm Allison.

As the storm moved inland and quickly lost wind strength and tropical storm status, heavy rainfall records were set within the five days the storm lingered in Southeast Texas. The storm moved north across Houston on June 6, and the next day, Allison stalled near Lufkin as a depression. It took a southwesterly turn on June 8 and by June 9, things began to get even more difficult.

Allison was dropping more than five inches of rain an hour. Incredibly, the storm had more life and from June 9 to June 17, it traveled east/ northeast through eight more states killing dozens and causing millions more in damages, becoming the costliest tropical storm in U.S. history.

In all, Allison lasted 27 days and traveled thousands of miles and became a storm for the record books.

Note: The video attached to this story was produced on the 16th anniversary of Allison’s landfall.

About the Authors:

KPRC 2's chief meteorologist with three decades of experience forecasting Houston's weather.

Journalist, meteorologist, community leader and volunteer.