Flooding, heavy rains expected this weekend in San Antonio area

Coming off a wetter than average April, San Antonio is expected to see a fresh deluge this weekend.

The area can expect to receive 3 to 6 inches of rain starting Friday and continuing through Sunday, which will likely include flash flooding, said Bob Fogerty, a meteorologist with the National Weather Service.

“We’ll be getting it in two rounds,” Fogerty said. “[Friday night] late in the evening, there will be heavy rains. There’s a possibility of strong thunderstorms and strong winds, as well as hail that is 1 to 2 inches [in size]. … Saturday and Sunday we may get another round of showers and storms.”

Added to the 4.75 inches of rain measured at the San Antonio International Airport during April, the rain likely will help recharge the Edwards Aquifer, which serves as the area’s primary source of drinking water. But Central Texas remains in drought and is likely to stay under drought restrictions even after this weekend, said Paul Bertetti, the Edwards Aquifer Authority’s senior director of aquifer science research and modeling.

“The rain in April certainly did help stabilize the aquifer a bit,” Bertetti said Friday. “We’re hearing that we’re going to see [about] 3 inches this weekend, which isn’t going to fix the drought in one day or even in a couple of days — but it helps.”

The weekend rainfall can be expected to raise the level of the aquifer’s J-17 Index Well, which is used to measure when pumping restrictions are needed, by 5 to 10 feet, Bertetti said. As of Friday, the well was at 640.6 feet with a 10-day average of about 639.7 feet — still considerably below its non-drought 10-day average of 660 feet or above.

On Monday, the Edwards Aquifer Authority declared Stage 3 pumping restrictions on permit holders utilizing the Uvalde Pool of the Edwards Aquifer, which lies west of San Antonio. Permit holders, including water utilities, farmers and ranchers in this area, are required to reduce their permitted water allowance by 20%.

As of Friday, the San Antonio area was still under the EAA’s Stage 3 pumping restrictions and SAWS Stage 2 watering restrictions. The EAA’s pumping restrictions limit the amount of water SAWS is allowed to pump from the aquifer, while SAWS’ watering restrictions limit how much water residents and businesses can use for irrigation.

While the Edwards Aquifer formerly served as SAWS’ only source of water, it now accounts for just about 50% of its water. The other 50% comes from a diversified portfolio that includes the Vista Ridge project, recycled water, Canyon Lake, the Trinity Aquifer and desalinated brackish water.  

Last year was the city’s second driest in recorded history with just 11.5 inches of rain — only 1917 was drier with 10.11 inches. Meteorologists and climatologists have said they expect San Antonio’s precipitation levels to return to its more typical average of about 31 inches this year. That’s because the La Niña weather pattern, which typically brings warmer temperatures but less rain to the southern United States, has ended, Bertetti said.

“What we have is a transition point,” he said. “Predictions are showing we could go into an El Niño pattern later this year. That could be important for us getting back to normal,” he said. El Niño typically brings cooler temperatures and more rain to the southern U.S.

San Antonio has recorded 8.39 inches of rainfall this year, NWS meteorologist Paul Yura said. May has only seen about half an inch thus far.

As of Friday afternoon, parts of south Central Texas through Sunday, including Bexar County, were under a flash flood watch. The forecast showed potential for rain in the area across the next eight days.

Flash flooding is especially likely following drought, because when heavy rains move in, the hard, compacted ground takes a while to soften up and absorb the water.

San Antonio lies in the middle of Texas’ Flash Flood Alley — so named for the area’s unique topography, shallow soil and high rainfall rates.

With flash flooding expected this weekend, residents are encouraged to utilize local tools such as the Bexar County Flood Map created by the San Antonio River Authority. The map is a live, active interactive webpage that shows which low water crossings are open and which are closed, said Katye Brought, the brand and public communications manager for the river authority. Brought reminded residents to remain cautious at low water crossings.

“Turn around, don’t drown,” she said. “Even if you think you can make it across, you may end up being swept away.”