Flash Flood — Harris, Texas

2015-05-25 to 2015-05-26 · near Nassau Bay, Harris, Texas

Event narrative

Heavy rain produced flash flooding in and around the city of Houston that caused numerous creek and bayou overflows. Multiple water rescues were conducted. Numerous roads were impassable due to flooding that was as high as six feet deep. Hundreds of vehicles were stranded in the flood water. Flood waters inundated at least 2,585 homes and 73 commercial buildings. Many bayous, including Brays, Keegans, Buffalo (610 Loop to Downtown Houston), White Oak, Armand, and Halls were out of banks. Additional flooding occurred along Brickhouse Gully, South Mayde Creek, San Jacinto River, Clear Creek, Rummel Creek, Willow Water Hole, Cypress Creek, Little Cypress Creek, Willow Creek and Spring Creek. There were six directly related drowning fatalities.

Wider weather episode

Across already very saturated grounds, a slow moving line of thunderstorms moved into Harris County from central Texas during the evening hours of the 25th. Very heavy rainfall began in the mid evening hours across the northern portions of the county, while additional thunderstorms developed over central Fort Bend County and moved into Harris County from the southwest. A period of thunderstorm cell training occurred from around 10 PM to 1 AM from Fort Bend County into north-central Harris County where the cells merged with the line of storms moving southward from northern Harris County. Thunderstorm cell mergers continued over central and southwest Harris County for several hours resulting in widespread significant flooding. The Houston/Galveston National Weather Service Office issued their first ever Flash Flood Emergency for this event. The area's worst flooding was focused across the western portion of Harris County from the northwest side of the City of Houston to Addicks to Sharpstown to Richmond in central Fort Bend County. Hundreds of water rescues (mainly motorists stranded on area freeways and roadways) were performed by various agencies during the height of the rainfall. After daylight on the 26th, the Houston Fire Department responded to many requests for assistance of residences in flooded homes. Seven fatalities were directly related and one additional fatality was indirectly related to the flooding. Three fatalities resulted from the capsizing of a Houston Fire Department rescue boat in Brays Bayou and the other four were all flooded vehicle related. Rainfall totals averaged 3 to 4 inches across much of Harris County with totals of 4 to 6 inches from Humble to Jersey Village to Katy, and then eastward to Galveston Bay. Rainfall totals of 8 to 10 inches were recorded on the northwest side of the City of Houston southwest to Sugar Land. A maximum rainfall accumulation of 11 inches was recorded at Brays Bayou and Beltway 8. A CoCoRaHS observer 6.2 miles west of Downtown Houston recorded 10.03 inches of rainfall. Another observer 3.4 miles northeast of Richmond in Fort Bend County recorded 11.88 inches of rainfall. Maximum rainfall rates included 4.8 inches in one hour, 8. 3 inches in three hours, and 10.1 inches in six hours. The combination of the heavy rainfall and associated overflow of area creeks, rivers and bayous caused flood damage to thousands of homes and close to 100 commercial buildings.

View location on OpenStreetMap → (29.5269, -95.0867)

Source: NOAA Storm Events Database, event_id 579777. Narrative written by the NWS forecast office that issued the report.