JOINT BASE SAN ANTONIO-RANDOLPH, Texas –
A thunderstorm that passed through Joint Base San Antonio-Randolph July 15 proved that even small weather incidents can become big forces of nature.
A system called a pulse thunderstorm, which had developed north of San Antonio, rolled through JBSA-Randolph around 2:30 p.m. for 45 minutes, producing winds up to 49 knots, or 56.3 mph, in localized areas - one knot below a severe storm classification - and knocking down two trees.
"This was a short-lived event not caused by a front, but by heating," Mike Brown, 12th Operations Support Squadron weather forecaster, said. "With these storms, heat causes air to rise and eventually collapse. In this case, there was no hail or tornadic activity."
Pulse storms usually produce severe weather for only short periods of time and can generate intense downdrafts of localized air called microbursts, which is similar to activating a leaf blower to the ground, Brown said.
Microbursts are able to topple fully grown trees.
"Any thunderstorm has the potential to cause wind damage," Brown said. "In the wrong place at the right time, even smaller 'garden variety' storms can be very dangerous."
The July event was "unremarkable," he added, but it showcased what a small storm can do if it travels through an area with trees and vehicles.
Besides lightning and high winds, flash flooding remains a top killer among severe weather hazards in the U.S., especially in Central and South Texas, where dry ground often cannot absorb moisture as quickly as it rains. The national 30-year average for flood fatalities is 127, according to the National Weather Service.
"Take cover, pay attention to weather updates from the radio or Internet and listen to the Giant Voice (at any JBSA location)," Brown said. "If you're outside and come to a flooded road, whether you're walking or driving, turn around."
For Diane Butler, JBSA-Randolph housing manager, storms can pose unsuspecting risks around trees.
"There's an assumption that when a tree falls, there's something wrong with it," she said. "The one that fell (at housing) and the ones with limbs torn off were healthy, strong trees. We encourage residents to not put up tree swings for their safety,"
While this year's hurricane season began June 1 and ends Oct. 30, "Texas is prone to thunderstorms year-round, so be prepared," Brown said.