Storms Could Weaken Texas Drought
Most of Texas is still in a moderate-to-severe drought, but a storm forming 2,000 miles northwest of Hawaii may be the key to drought relief for the state, says a Texas A&M University professor who also serves as the state climatologist.
John Nielsen-Gammon, professor of atmospheric sciences, says that precipitation everywhere in the state has been running below normal since Oct. 1.
"So far, this has been one of the five driest October-Novembers on record statewide and the driest since 1950," he explains.
"Most major metropolitan areas of the state received ample rainfall this summer, but it's been a different story to the south and west. For more than half of the state, the drought of 2011 never went away, and Texas is now into its third year of drought.
80 percent of Texas is in drought
"I'm expecting a wet weather pattern to develop next week. The seeds for that pattern are being planted right now, as a storm system intensifies way out in the middle of the Pacific Ocean."
Nielsen-Gammon says that the storm will cause a wave to develop in the jet stream, driving it northward toward Alaska. Downstream, over the western United States, the jet stream will overshoot to the south, causing a stationary trough to form over the Southwest.
"For wet weather in the wintertime, we need the jet stream to dip southward across the southwest United States so that upper-level winds over Texas are strong and from the southwest," he notes.
Such a weather pattern allows moisture to be drawn into the state from the Atlantic, while at the same time providing the weather disturbances that convert that moisture into clouds and precipitation.
"When that trough forms over the weekend, we'll have the necessary ingredients in place for at least one widespread rain event across Texas, and hopefully several of them," Nielsen-Gammon predicts.
If the storm does develop, it wouldn't end the drought statewide, but it would improve reservoir levels and provide some last-minute hope for the winter wheat crop, he says.
"Much of the state is bone-dry," Nielsen-Gammon says. "We really need this wet weather pattern in order for reservoir levels to start moving in the right direction."
Drought conditions have rapidly expanded across the state. According to the U.S. Drought Monitor, more than 80 percent of the state is in drought, the highest total since March 2012.
Last summer, there had been widespread hope among forecasters that a developing El Nino event in the tropical Pacific would lead to above-normal rainfall across Texas this winter, but the El Nino never materialized, he points out.
"This year's neutral conditions in the Pacific favor neither an unusually wet winter nor an unusually dry winter," Nielsen-Gammon explains. "That's why the dry weather so far has been a surprise."
From TAMU Times December 5, 2012
Media contact: Keith Randall, News & Information Services, at 979.845.4644 or John Nielsen-Gammon at 979.862.2248