Despite recent rains, much of Texas is still in a severe drought and the long-term outlook is mixed, according to a Texas A&M University expert with a long track record of studying the state’s often mysterious weather conditions.
John Nielsen-Gammon, Regents Professor of Atmospheric Sciences who also serves as the state climatologist, says recent rains have helped to alleviate conditions over parts of the state, with some areas reporting the wettest February ever. But much of Texas still needs a lot of rainfall to break a year-long drought that has been one of the worst in history, he contends.
“Both December and January were above normal for Texas rainfall, and combined, October through January were near normal,” Nielsen-Gammon reports.
“But despite recent rains at the end of the year, when the final numbers are in, calendar year 2011 rainfall will probably come in second to 1917 for the driest year on record.
“A few counties in the Dallas area are now drought-free, according to the U.S. Drought Monitor, but in most of the rest of the state, the recent rains have only partly improved conditions.”
Many of the state’s lakes and reservoirs have yet to recover, says Nielsen-Gammon. Some lakes are still down 10 to 20 feet or more.
“Most reservoirs in the Dallas area are full, and some in Northeast and East Texas have shown substantial improvement since last fall,” he notes. “At the same time, most major reservoirs in western and southern Texas have yet to show much improvement.
“It takes time for reservoirs to fill,” he adds. “The first rains simply make the top of the soil moist. The next storms will allow water to penetrate deeper into the soil and to start producing runoff as the soil cannot absorb much more water. Lakes and reservoirs are typically the last to respond to changing drought conditions.”
Nielsen-Gammon says the soil situation can be compared to what he calls the “dunked biscotti” model named after the Italian hard biscuit. “Like a dunked biscotti, the outer layer of the ground is moist and loose, while deeper layers are still dry and crunchy,” he says.
Long-range forecasts are not especially rosy, he adds.
The 2011 drought set records all over the state, and summer temperatures hit all-time highs in several locations, adding to the drought misery. The drought caused dozens of wildfires, and the Texas Forest Service has estimated that dry conditions have killed tens of millions of trees in Texas.
“Although this La Niña year has been relatively wet, the Climate Prediction Center is still calling for below-normal rainfall through June,” Nielsen-Gammon says. “Still, though, Texas is set up for a major rain event Friday and Saturday, with more rain likely during the middle of next week. At this rate, we might end up with one of those rare wet La Niña years, which would be great.
“A large portion of our rain typically falls in May, and this spring will make the difference for reservoirs in drier portions of the state. By summertime, the odds have evened out and it could easily be wet or dry. But the bad news is that the summer forecast calls for enhanced chance of above-normal temperatures, which would increase evaporation and water demands.”