Records fall: NWS sees hotter than normal temps through August

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Park visitors and their dogs take shelter from the sun under a tree in the browned grass of Dixieland Park July 20, 2022, in Harlingen. (Denise Cathey/The Brownsville Herald)

The National Weather Service Brownsville-Rio Grande Valley station has issued its outlook for August through October, and maybe it would have been better if they hadn’t.

A key takeaway is that NWS has “medium-high confidence” that above-average temperatures will continue through October in the Rio Grande Valley, and “highest confidence” that August will follow July as a top-five to top-10 hottest month on record for the Valley.

Since the start of the current heat wave on June 9, thanks to a high-pressure dome parked over South Texas and northern Mexico, temperatures in the Valley have ranked among the top three hottest on record, with Brownsville smashing records since 1878, Harlingen since 1912 and Port Mansfield since 1958, according to NWS.

NWS Warning Coordination Meteorologist Barry Goldsmith said the rainfall forecast is less certain, with equal chances of above average, below average or the same.

“August has the best chance for being drier than average, but uncertainty is the word for September and October,” he said.

A major concern continues to be dangerous levels of heat, made more dangerous when accompanied by high humidity, Goldsmith said.

“So far this summer, we’ve issued more than two dozen heat advisories, which is far above expected, and several excessive heat warnings,” he said. “Expect several more of one (or) both through August and perhaps into September.”

A heat advisory is issued when heat indexes of 111 or higher are forecast for at least two hours during an afternoon.

Normally, NWS issues only from two to five of them per summer. An excessive heat warning is issued when heat indexes of 116 or higher for two or more hours in an afternoon. “Heat index” is a calculation of how hot it feels based on actual temperature plus with humidity.

Another big concern remains drought and water supply, with limited rainfall expected in the Lower Rio Grande watershed, which feeds Falcon Reservoir in addition to the river, according to NWS, which noted that Stage 2 water restrictions could be implemented by early August if the U.S. share of water in the Falcon and Amistad reservoirs falls below 25 percent.

Also worrying is the potential for rapid spread and growth of wildfire in grass and brush, especially “across the mid/upper Valley/Brush Country/Rio Grande Plains, continuing into August and potentially longer if rains don’t come,” NWS said.

Remnants of scorched earth left by a grass fire near Olmito Monday afternoon, July 10, 2023, are seen as a heat advisory continues for most of South Texas. (Miguel Roberts/The Brownsville Herald)

Also, though it may seem counterintuitive in the face of a “hot, leaning dry” outlook, there’s a chance for flooding rain with the peak of the Valley’s rainy season, late August through early October.

“One strong energy wave, or a slow moving tropical cyclone reaching our shores, can turn drought into flood very quickly,” Goldsmith said. “While confidence is low, we’ve seen this story before — as recently as last August 14-15.”

Tropical cyclones, from depressions to hurricanes, remain a “wild card” for the Gulf of Mexico and southwestern Caribbean Sea, which means it’s important to stay vigilant during the Valley’s peak season, August and September, he said.

“It only takes one,” Goldsmith said.

He recommended that resident take advantage of the current dry weather to revisit hurricane preparedness plans, shore up homes and buildings and prepare for possible flooding — while following safety tips for extremely hot weather.

Meanwhile, with back-to-school shopping just around the corner, NWS again reminds residents to “look before you lock” in order that children and pets not be accidentally locked inside vehicles, since heat stroke can occur in minutes in such situations. It’s also important to practice water conservation with things so dry, Goldsmith said.

“We’ve been hitting this since the early spring drought,” he said. “The late March through early June rains temporarily helped Valley retention/detention ponds, but that help is long gone.”