The drought that has persisted across most of the Southwest for three months short of three years is on track to be the second longest drought in Texas history. And if the trend doesn’t turn soon, the current dry spell could rival the legendary drought of the 1950s.
That’s the less than uplifting outlook Texas State Climatologist John Nielsen-Gammon offered during a “Water Woes” panel discussion at the annual Texas Produce Convention Thursday (Aug. 8) in San Antonio.
As for short-term predictions, Nielsen-Gammon quipped: “We have a high degree of confidence that we don’t know what will happen.”
That admission comes from the current neutral position of the El Nino/La Nina phenomenon that climatologists say means weather patterns have an equal chance of being either wet or dry. “We see nothing to direct our weather one way or the other,” Nielsen-Gammon said.
“We do see a link between the Pacific Ocean and Texas weather.”
For the longer term, however, much of the Southwest appears to be in a prolonged period of drier than usual weather. The combination of Pacific and Atlantic water temperatures currently favor dry conditions in parts of the region. Nielsen-Gammon said the situation is similar to conditions in the 1950s.
“If the Atlantic Ocean is warm we get dry. If it’s cold, we are wet. We don’t have the tools available to make forecasts based on the Atlantic water temperature, but we know that cycles may last for several decades. Over the long term, we can see a 10-percent to 20-percent difference in rainfall (depending on Atlantic water temperatures). We’re in the middle of a period when our weather is typically drier than normal.” He says Texas weather is rarely normal but consists of extremes.
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Summer rains across much of Texas provided some temporary decrease in water demand but if recent drying conditions and high temperatures persist, demand will increase again. “Overall, those rains have not improved drought conditions. We are in a dry year that comes on top of two previous dry years.”
The persistence makes this drought a contender for second place all-time in Texas drought history, based on records going back to 1899. “The drought of the 1950s will be the only one longer if this drought persists until the end of the year,” Nielson-Gammon said.
“Reservoirs continue to set records for low capacity,” he added. “It is possible that reservoir levels can drop to an all-time low if drought continues. Recent rains have helped a little.”
He said the El Nino/La Nina factor will be important for the next few months and that measurements show warmer water beneath the surface cool water in the Pacific area that creates the weather patterns. “The LA in La Nina,” he said, “means less agua.”
It’s the cool water that prompts La Nina and the cool surface temperatures would hint at a dry winter. But the deeper, warmer water could offset that. That’s why the neutral status is in play and why predicting this winter’s weather remains difficult.
He also said a normal rainfall pattern in West Texas would not be enough to reverse the drought.
The next few months will be important. “September and October is when two-thirds of extreme rainfall occurs in the region. But that’s only for parts of the state.” A wetter September, he added, would improve the moisture situation and offer some cooling as well.