Tropical Storm in Texas, June 5 to 10, 2001

Tropical Storm Allison formed in the northwest Gulf of Mexico during the early afternoon of June 5th, 80 miles south of Galveston. Allison moved northward, making landfall on the west end of Galveston Island between midnight and 1am on the 6th, less than 12 hours after forming. As Allison moved inland it caused two to three foot tides, which had little impact on the area. On the evening of the 5th a tornado briefly touched down in Brazoria county causing damage to one home in the Manvel area. Over the next five days Allison produced record rainfall that led to devastating flooding across Southeast Texas, killing 22 people and damaging over 48,000 homes, 70,000 automobiles and nearly 2000 businesses.The first significant flooding occurred while Allison was still offshore. A large spiral band with very heavy rainfall moved inland from Galveston to the Houston area, and by mid evening 8 to 12 inch totals were common from northern Galveston county into southern Harris county. Heavy rain continued over inland portions of Southeast Texas overnight with 3 to 5 inch totals common, as Allison moved inland and weakened.On the morning of June 6th, Allison was downgraded to a tropical depression. Allison moved north until it was near Lufkin, then made a clockwise loop and began drifting to the southwest. Before sunrise on June 7th, the center was near Huntsville, and a band of heavy rain moved into Liberty county producing 5 to 10 inches of rain, causing almost a foot of water on Highway 90. Around the same time another area of thunderstorms developed over the Sugar Land - Stafford areas of Fort Bend and Harris counties, producing another 8 to 12 inches of rain and causing abundant street flooding and water in some homes. During the day moderate to heavy rain continued over Brazoria, Houston, Liberty, Polk, Trinity and Walker counties resulting in additional reports of flooding.June 8th began with another 5 to 10 inches of rainfall along the immediate coast, causing flooding in southern Brazoria county, central Galveston county and northern Chambers county. Skies cleared for a few hours, but the rain began again that afternoon over Montgomery county. Thunderstorms intensified rapidly over southern Montgomery and eastern Harris counties and began to train across the Houston metro area that evening and into June 9th. Very heavy rainfall was observed for up to 10 hours in some locations, and rainfall rates of 4 inches or more per hour were observed throughout the night. Flash flooding initiated quite rapidly during rush hour late Friday afternoon. Widespread street flooding was the initial threat, but the high rainfall amounts forced almost all the major Houston area bayou systems into severe flooding, with some to record levels. The flooding caused a complete shutdown of downtown Houston, including all major roadways and both major airports for more than 12 hours. The Texas Medical Center along Brays Bayou sustained severe damage resulting in the complete shutdown of several hospitals and a significant loss of research data. Twenty-two people lost their lives due to the flash flooding in Harris county on the 8th and 9th.On June 9th the circulation center of the storm gradually made its way toward Palacios. Before moving offshore, another round of heavy rain developed across southern Harris and extreme northern Galveston counties. This caused flooding along Clear Creek, putting water in homes in the Friendswood, Webster and League City areas.