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Oklahoma researchers develop system to predict flash floods

NORMAN — Last year, 16 people died in a series of flash floods that swept across Oklahoma in late spring and early summer.

Now, scientists at the National Oceanic and Atmospheric Administration's National Severe Storms Laboratory in Norman are developing techniques for predicting deadly flash floods hours ahead of time and giving residents more reliable information about when and where they might happen.

Scientists at the laboratory are working on a system called Flooded Locations and Simulated Hydrographs, or FLASH. J.J. Gourley, the lab's research hydrometeorologist, said the system uses data on terrain types across the United States to help National Weather Service forecasters determine where heavy rainfall is most likely to cause floods.

The project began in 2012, and grew largely out of the Multiple Radar Multiple Sensors system, another system researchers at the lab developed to bring together data on weather events like heavy rain, hail, snow and tornadoes. Researchers completed work on that project earlier this year.

The FLASH system is designed to combine rainfall data from the other system with data from a number of other sources to help meteorologists determine where flash flooding is most likely. The result will allow National Weather Service forecasters to give more accurate, more narrowly tailored forecasts for flash floods within a six-hour period, said Steven Martinaitis, a researcher at the lab.

For example, instead of issuing flash flood warnings for an entire city, forecasters will be able to give forecasts for the individual streets or neighborhoods that are at greatest risk.

The new system divides the United States into 1-kilometer grid squares. Using data from NASA, the system shows the terrain type that's most common in each grid square. Forecasters will be able to use that information, along with data about the area's soil saturation, to predict how rain will behave once it lands.

For example, in an urban area with paved streets and parking lots, the system would show water pooling and running off into streams. In open areas with sandy soil, rain water would be more likely to soak into the ground.

The spring of 2015 was a particularly deadly period, both in Oklahoma and nationwide. From May 5 to June 18, a series of powerful storms swept through Oklahoma, causing flash floods and river flooding in several parts of the state. The floods left 16 people dead, the state medical examiner's office reported.

Among the dead were Capt. Jason Farley, a Claremore firefighter who drowned May 23 during a high-water rescue at an apartment complex. City officials said Farley, 44, stepped into a ditch and was swept into a drain pipe. His body was recovered the following day.

The same week, William Lee Gamblin, of Hugo, drowned after his Chevrolet pickup stalled while he was driving on a flooded road in rural Choctaw County, the Oklahoma Highway Patrol reported. Gamblin, 32, climbed out of the truck and waded through floodwater to try to find help. But when he went back to his truck to try to save some personal items, he stepped into a dip in the road, went under water and never resurfaced, troopers said.

That trend wasn't limited to Oklahoma. In 2015, 176 people died nationwide in floods — nearly twice the 10-year average of 82 flood deaths per year, the National Weather Service reported. Of that total, 129 people, or about 73 percent, died in flash floods, 112 of them in vehicles while trying to drive through floodwater.

Researchers plan to test the new system at the laboratory's annual five-week spring experiment, which begins next month. If the trial is successful, Gourley said the new system could be operational by early June.

Silas Allen

Silas Allen is a news reporter for The Oklahoman. He is a Missouri native and a 2008 graduate of the University of Missouri. Read more ›