Flash floods a rising concern as more rain falls across North Texas

Rain is already falling in some parts of North Texas Tuesday and forecasters have issued a flash flood watch for most of the area that includes the Metroplex.

Rain should start moving into Tarrant County this afternoon. The National Weather Service is predicting tjat 2 to 4 inches could fall across North Texas through Friday with some areas seeing up to 5 inches.

“The next 24 hours we could see 1 to 2 inches across North Texas,” said National Weather Service meteorologist Jamie Gudmestad. “It’s just going to keep raining throughout the week.”

West of Fort Worth, the Brazos River is rising as water is being released from Possum Kingdom Lake. The water will impact the low-lying Horseshoe Bend area in Parker County that has already seen high water several times this year.

Forecasters are predicting a minor flood of 24.4 feet, just below a moderate flood, at Dennis gauge above Horseshoe Bend. But that forecast is likely to change as more rain falls.

Judi Pierce, a Brazos River Authority spokeswoman, said authorities hopes the rain is light enough that they don’t have to open any more gates today. But heavy rain was falling around lunchtime at the Morris Shephard dam. A flash flood warning was in effect for parts of Palo Pinto and Stephens counties until 3 p.m. Another flash flood warning is in effect until 4:15 p.m. for Erath County.

The two gates are releasing about 19,600 cubic feet per second. That’s enough to fill an Olympic-sized swimming pool every five seconds or about a quarter of the flow at Niagara Falls.

The repeated rounds of high water have angered and frustrated Horseshoe Bend area residents who have questioned the releases by the Brazos River Authority.

“I think it’s fair to say the bathtub is full,” Pierce said.

The Brazos, which runs more than 800 miles from New Mexico to the Gulf of Mexico in Freeport, is also flooding in central and south Texas, where at least six people have drowned. The river is expected to crest at record levels later Tuesday in Fort Bend County, southwest of Houston.

The Brazos River Authority manages 11 lakes along the Brazos River and all of the lakes are close to or at capacity.

“There are two kinds of reservoir dams,” Pierce said. “The Corps of Engineers have flood control reservoirs. At the time they are full, they have a good amount of space to hold floodwaters. At Possum Kingdom and Granbury, these reservoirs are not built for flood control.”

That means that those lakes must release water once they are full.

“At conservation level, the water actually comes to the top of the dam,” Pierce said. “If we do not release water when we are full, the water will automatically go into the emergency spillway and over our dam gate. It can cause those gates to fail and of course in a worst-case scenario, it can cause the dam to fail.”

West of Possum Kingdom, the Hubbard Creek reservoir is also full for the first time since April 2008 and is releasing water that will flow into Possum Kingdom. Hubbard, just outside of Breckenridge, was just 30 percent full one year ago.

Greg Waller, a service hydrologist with the National Weather Service West Gulf River Forecast Center, said people need to pay attention to storms this week.

“It’s not going to be the amount as much as the intensity,” Waller said. “The soils are saturated. We are anticipating river flooding. The flood control lakes are storing what they can but the water storage lakes have to pass through those inflows. It’s going to be a very sensitive time this week.”

The Tarrant Regional Water District is also watching rainfall closely.

Both Lake Bridgeport and Eagle Mountain lake can hold additional water but it will likely result in the flooding of some homes.

“There’s a good chance we will be flooding the lowest house at Lake Bridgeport again this week if the forecasts are correct,” said David Marshall, TRWD’s director of engineering and operations support. “Our biggest concern is if we get a thunderstorm that dumps a three-inch rainfall in the Lake Bridgeport watershed. That could change things quickly.”

Horseshoe Bend is getting used to the rain:

This story was originally published May 31, 2016 at 12:51 PM with the headline "Flash floods a rising concern as more rain falls across North Texas."