COLLEGE STATION, July 28, 2011 — Tropical Storm Don, now moving across the Gulf of Mexico toward the Texas coast, is not potent enough to break the ongoing Texas drought, says Texas State Climatologist John Nielsen-Gammon.
“It’s been so dry in Texas for so long, this one storm will be a drop in an empty bucket,” says Nielsen-Gammon, who is a professor of atmospheric sciences at Texas A&M University in addition to serving as the state climatologist for Texas.
According to the National Hurricane Center, Don was located 425 miles east-southeast of Corpus Christi as of 4 p.m. today (Thursday) and was moving northwest at 16 miles per hour. It carried with it sustained winds of 45 miles per hour and was given an 11 percent chance of reaching hurricane strength prior to landfall.
“For rainfall potential, it doesn’t really matter whether or not it becomes a hurricane,” says Nielsen-Gammon. ”Hurricanes are windier, but they’re not rainier. Some of Texas’s worst floods have come from tropical storms or tropical depressions.”
One of the more memorable recent floods was produced by the remnants of Tropical Storm Allison. It dropped three feet of rain on parts of Houston in June 2001, recalls the Texas A&M professor.
“We’re not likely to see an Allison-type flood from Don,” Nielsen-Gammon says. “Allison wandered around East Texas for several days and stalled over Houston. Don is forecasted to keep moving northwest after making landfall. So it should produce a broad swath of moderate rain rather than a concentrated flood.”
The National Weather Service’s Hydrometeorological Prediction Center (HPC) is forecasting 3″ to 5″ in a 100-mile-wide swath along the path of the storm after it makes landfall. Precipitation amounts are expected to decrease as it moves farther inland.
Nielsen-Gammon warns that some flooding is not out of the question. “It’s always possible that an individual cluster of thunderstorms will end up stalling or regenerating over one particular area and produce a localized flood event. Del Rio’s 1998 flood was caused by just a few thunderstorms embedded in Tropical Storm Charley,” he notes.
What does Don mean for the Texas drought? ”Unfortunately, Don is a fairly small storm at this point,” Nielsen-Gammon says. “The majority of the state will probably receive little or no rainfall. The drought is going to continue.”
Don would have to dump about two and a half inches across all of Texas to prevent the state from having its driest January through July on record, according to statistics compiled by Brent McRoberts of the State Climate Office.
“The lucky areas, if they receive 2″ to 5″ of rainfall, will be picking up one or two months’ worth of precipitation,” Nielsen-Gammon says. “That’s not enough to end the drought, but it will help reduce irrigation demands and perhaps let struggling ranchers produce another cutting of hay.”
Don might even be bad news for some, according to Nielsen-Gammon. “The area around Victoria and Corpus Christi has been suffering, but they’ve managed to get just enough rain at just the right times to produce some decent crops. Right now, according to Texas AgriLife Extension Service, part of The Texas A&M University System, the cotton harvest is under way. If Don dumps a bunch of water on cotton that’s about to be harvested, it will hurt rather than help.”
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Contact: John W. Nielsen-Gammon, Professor and Texas State Climatologist, Dept. of Atmospheric Sciences, Texas A&M University, (979) 862-2248 or n-g@tamu.edu; Lane Stephenson, News & Information Services, at (979) 845-4662 or l-stephenson@tamu.edu.
