May lives up to reputation as severe weather month in Central Texas

Updated May 10, 2016

By the time you read this, large hail and damaging wind gusts might have struck Central Texas. If so, it would not be out of character; May is the month that tends to bring the most severe weather.

May has brought the most tornadoes, hail and severe thunderstorms, according to data provided by the National Weather Service. Since 1955, May has produced 1,092 reports of severe hail and 501 instances of high winds — numbers significantly higher than in any other month — in the weather service’s Austin-San Antonio region, which includes Central Texas and parts of South Texas. Since 1950, there have been 192 tornado reports in May, more than twice as many as any other month.

The weather service Tuesday afternoon put in place a severe storm watch through 10 p.m. for more than 60 Texas counties from South Texas to the Oklahoma border, including Travis, Williamson and Hays counties.

But what’s severe weather? It is not lightning, nor is it flooding, actually. Rainfall is not included in the official definition of “severe,” though a year ago, on Memorial Day weekend, storms brought devastating flooding to San Marcos, Bastrop and other parts of the region — and this spring’s rains have saturated the ground.

Severe weather does include hail at least the size of quarters, winds of 58 mph or stronger and tornadoes. Tuesday night’s outlook called for hail as big as baseballs and damaging winds of more than 60 mph in the Hill Country and areas west of the Interstate 35 corridor.

The threat posed by tornadoes and high winds pales in comparison with that of flooding in Central Texas. Still, tornadoes have occasionally struck with devastating effects, such as on May 27, 1997, when a tornado tore Jarrell apart, leaving 27 people dead.

Despite the Jarrell tornado, May actually does not produce the most severe tornadoes in Central Texas, said Troy Kimmel, a forecaster and instructor at the University of Texas. April tends to produce the most severe ones, he said.

Though tornadoes rarely cause deaths in Central Texas, they can cause severe property damage, said Bob Rose, a meteorologist with the Lower Colorado River Authority.

He said a confluence of meteorological phenomena creates tornado alley, of which Central Texas is on the southern end. Warm and moist air moving northwest from the Gulf of Mexico, warm and dry air coming east from Mexico, and cold and dry air coming south from Canada meet over the Midwest and parts of Texas, creating the unstable conditions that lead to tornadoes, he said.

During a tornado warning, look for a closet or other interior room that can “put as many walls as possible between you and the outside,” and if possible get under a closet or table, Rose advised Tuesday in his weather blog.

“Tornado activity,” Rose said, “really starts ramping up right now.”