Canadian Underwriter

Parts of Texas see 10 to 20 inches of rain in 24-hour period: AIR Worldwide

June 7, 2016   by Canadian Underwriter

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Texas, still drying out from one of its wettest springs on record, received additional heavy rainfall during the last two weeks, causing major flooding throughout the state, catastrophe modelling firm AIR Worldwide said on Monday.


In Brenham – a town between Austin and Houston – 16.62 inches of rain fell in one day. Photo: @ClimateCentral.

AIR Worldwide said in a media advisory that areas around Austin, San Antonio, Houston, College Station and Dallas were significantly impacted. As rivers rose beyond their flood levels and flash floods raced through bayous and low-lying areas, residences, commercial properties, vehicles, agricultural land and drilling fields were swamped, while roads were shut down and even washed out, and bridges were damaged. Governor Greg Abbott declared a state of disaster in 31 counties – more than more than 10% of the state’s counties – on June 1.

AIR Worldwide said that according to news reports, flooding in Brazos – extending from north and central Texas to the Gulf of Mexico – has affected more than 2,000 residences, prompting hundreds of rescues, closing a number of roads, prompting thousands of evacuations (both voluntary and mandatory) and filling shelters to capacity.

“During the last two weeks of frequent, intense, and often slow-moving storm systems, extraordinarily high rainfall amounts were recorded in many communities in Texas,” said Dr. Marc Marcella, senior scientist at AIR Worldwide, in the statement. “Many areas recorded very heavy rainfall amounts, 10 to 20 inches in a 24-hour period, and during this storm period a large swath of the state also saw more than 400% to 600% of the long-term average rainfall. Flash flooding ensued due to the very high intensity of downpours, as high as three inches per hour in some locales.” For example, Dr. Marcella said, in Brenham – a town between Austin and Houston – 16.62 inches of rain fell in one day.

The storm systems responsible for the massive flooding have now dissipated, along with flood levels in most places, however flood damage and cleanup will “persist for some time,” AIR said in the statement. Parts of other states, such as Oklahoma and Louisiana, were also drenched by the storm systems affecting Texas, although flooding has not been as severe and dramatic in those areas.

According to AIR, during the last two months, Texas has received substantial amounts of rain: three feet in some eastern parts of the state. In late May, there was as much as 20 inches of rain in some areas, and as much as eight inches in the Dallas area between May 1 and 2.

“With many rivers already high, the torrential rain of the last two weeks pushed them beyond flood state, and many reached historic or near-historic levels,” said Dr. Hemant Chowdary, principal scientist at AIR Worldwide, in the statement. For example, the Brazos River crested in Richmond at 54.81 feet on June 2, breaking the previous flood record set in 1994 by more than four feet.

Aside from far northern and far western areas of Texas, most of the state has been affected by the recent two weeks of heavy precipitation. The flooding impacts have been substantial, from property damage to closed highways (including interstates and other major roadways), affecting both travel (nearly 200 flight cancellations in Dallas and Houston) and commerce. Hundreds of water rescues have taken place, and some communities – such as Kingdom Heights, west of Houston – have been isolated since highways became impassable, AIR said.

“At one time or another, most of the state of Texas was under a flash flood watch or warning, impacting tens of millions of people,” the statement said. Power failures related to flooding were reported in some areas. Although oil and gas refineries in Texas appear to have avoided damage, some oil wells were shut because of floods, and select oil and gas operations were curtailed.