Scorching temperatures usher in drought throughout Brazos basin, state

A hotter than usual start to the summer has helped to compound the problem of increasing drought conditions throughout the Brazos River basin, with sporadic rainfall offering some relief for limited areas, but not nearly enough to offset the widespread dry conditions through much of the state.

The National Weather Service’s Climate Prediction Center forecasts a 60 percent chance of hotter than normal temperatures through August for most of the state, with a portion of East Texas having a 50-50 chance at hotter than normal temperatures. Meanwhile, the summer precipitation outlook through August forecasts an average amount of rainfall, neither greater nor lesser than usual.

The hot and dry conditions follow a time when winter drought conditions were alleviated somewhat by spring rainfall, according to Curtis Adams with Texas AgriLife Research. While that rain certainly helped, he said, it was not enough to completely eliminate the drought, which is increasing with climbing temperatures and lack of consistent rainfall.

“We went more than 100 days without rain this (past) winter,” Adams said. “The (spring) rains helped turn things around, but they didn’t make up for the extreme water deficit.” He noted that the lack of moisture will make it difficult for many plants – including crops – to withstand the summer drought.

Higher than average temperatures earlier in the summer meant evapotranspiration rates have occurred earlier than usual, Adams said. Evapotranspiration refers to water loss to the atmosphere by the evaporation of moisture from the soil as well as transpiration from plants.

Adams told AgriLife Today that adding to the concern of heat and drought are windy conditions that have resulted in the loss of up to half an inch of water from the soil each day.

Texas Climatologist John Nielsen-Gammon noted that warmer conditions are increasing the loss of moisture to evaporation. Parts of the state experienced some relief thanks to mid-July rainfall, he said, while other parts of Texas remain locked in drought.

“Texas saw overall improvement of drought conditions (thanks to that July rainfall), Nielsen-Gammon said. “Currently, less than 80 percent of the state is considered abnormally dry or in some classification of drought,” he noted in mid-July. A week earlier, 84 percent of the state was experiencing those conditions. Southeast Texas experienced the most notable improvements, Nielsen-Gammon said.

The worst drought conditions continued to be spread through areas of the Panhandle, West Texas and portions of North Texas, he said.

A bit of bad news for Texas heading into late July are that many areas were forecast to see an extended period of 100-plus degree temperatures, including portions of the basin stretching from Lubbock and Granbury to Waco and College Station.

Hotter temperatures mean drier conditions, and vice-versa, Nielsen-Gammon said.

“The drier the ground is, the hotter it gets,” he said. “A lot of the state doesn’t have excess soil moisture.” That has been especially true in western portions of the state, including the Texas Panhandle, which has experienced the worst of the Texas drought through the first half of 2018.

After a cooler than usual April, summer heat arrived early with a vengeance. Nielsen-Gammon noted that May 2018 was the second hottest May on record for the state. He added that the change from cooler April weather to warmer May weather was the biggest temperature swing for those months on record.

June is historically a wet month for Texas, he noted, but the drying trend meant a worst-case scenario of the state returning to the kind of drought conditions that plagued the state during the height of the drought in 2011.

“It’s hard to improve drought conditions in July and early August,” Nielsen-Gammon said.

Ironically, drought conditions did improve somewhat in parts of the state thanks to July rainfall, but then scorching temperatures an average of five to 10 degrees above normal baked the state because of a heat dome that settled across Texas.

Accuweather noted that Lubbock and other areas of the Texas Panhandle received only half their normal amount of rainfall heading into late July. Meanwhile, much of the rest of the state also experienced less rainfall than normal, despite sporadic showers that would drench one area and leave a nearby area dry.

An early warning for the type of weather Texas could expect was evident even as summer began, which averaged 84 degrees through the early part of the month.

“There have been only two Junes overall that averaged warmer: 2011 (85.2 degrees) and 1953 (85.0 degrees), Nielsen-Gammon said. Noting that both of those were years of severe drought, he added, “That’s not good company. The high temperatures accelerate the loss of water from the soil, and the dry soil permits higher temperatures. This feedback produces dry conditions and stress in vegetation. Evaporation also helps deplete water supplies, but a bigger drain on water supplies is the increased irrigation and yard watering as people watch their plants wilt.

“There’s a little bit of feedback on precipitation too, with dry conditions making it harder for thunderstorms to develop, but weather disturbances can easily overcome that and we have a ready supply of moisture for the atmosphere just to our southeast (the Gulf of America).”

How have La Niña weather patterns affected the drought, and will this continue?

“La Niña contributed to the dry conditions across much of the state this past fall, winter and spring, but La Niña is over and above-normal temperatures are starting to show up in the tropical Pacific,” Nielsen-Gammon said. “There’s not a big impact on Texas rainfall anyway, except that the apparent beginning of El Niño development will hinder Atlantic hurricane development.”

The abnormally warm start to the summer helped set the stage for continuing high temperatures, he said.

“The seasonal outlook calls for enhanced chances of above-normal temperatures,” Nielsen-Gammon said. “With climate change, that was going to be the forecast anyway, but the warm weather (experienced during the first weeks of June) will almost be enough to lock in a warm summer overall.”

Texans are no strangers to summer heat and have been through this routine before, but Nielsen-Gammon did have one reminder for people regarding outdoor watering.

“Watering during the early morning will help ensure that most of the water actually reaches the soil rather than evaporating on the way there.”

Drier conditions are definitely having an impact on reservoir levels throughout the Brazos basin, although Water Services Manager Aaron Abel said the BRA water supply system is in better shape now than what was experienced during the devastating drought conditions of 2011.

“We don’t anticipate getting to the worst case scenario,” Abel said, pointing to the rainfall that brought some relief to the basin during the first two weeks of July. With summer heat intensifying at the end of July, drier conditions along with higher demands and evaporation rates are anticipated, but not the type that would likely lead to the extreme conditions brought on by 2011.

Meanwhile, the drought index for mid-July showed that the majority of the basin was experiencing drought conditions. Statewide, 75.13 percent of Texas was at least abnormally dry, while nearly half the state (49.41 percent) was experiencing moderate to exceptional drought conditions.

Hot and dry weather means the number of Texas counties with outdoor burn bans has increased as summer continues. As of July 17, a total of 135 Texas counties had enacted burn bans, with the vast majority of these in West Texas. The most recent information about burn bans can be found here.

The National Weather Service Climate Prediction Center’s Seasonal Drought Outlook indicates that through Aug. 31, drought is expected to develop or persist through much of southern and western Texas. The good news is that will drought conditions are expected to improve somewhat in the Panhandle.

While heat and drought may seem relentless now, there is hope on the horizon for relief. While neutral conditions (neither influenced La Niña or El Niño weather patterns) are expected to linger through much of the fall, the National Weather Service’s Climate Prediction Center indicates there is a 50 percent chance of El Niño returning this winter. The El Niño weather patterns resulted in drought-busting weather in 2015 and 2016, helping to replenish reservoirs and drench the Brazos River basin after it had been parched by years of dry conditions. While that development is uncertain, a clearer picture of what to expect should emerge in the coming weeks.