A Bat-eating Supercell and Other Mexican Storm Imports

While working a South Texas severe weather event a few days ago, I took note of the expanding rings on several 0.5 degree reflectivity cuts from Del Rio and New Braunfels. These are pretty common in those parts, actually — swarms of bats leaving their caves for their nocturnal bug feast.

There was just one little problem: part of one of the swarms was about to get munched by an intensifying supercell that had formed in the Serranias del Burro range of Mexico, then moved across the Rio Grande in a collision course with the bats. It clearly was going to be a bad night (and probably a deadly one) for some of those bats!

The web page is featured here (until the next Cool Image update, where it will get a link from the bottom).

It has been a long time since I’ve had the time and opportunity to add anything new to the Cool Image page at work. Sometimes I notice interesting phenomena, but the shifts are too busy to gather images. Sometimes long stretches will pass by before I see (or someone else points out) something that would be great for that page. Often I see suggestions after the imagery already has been purged from the systems (usually within about two days, because of space limitations on the storage discs). Fortunately I was on duty for this peculiar event, and had just enough time in between map analyses, mesoscale discussions and other work to grab the imagery.

As luck would have it, I’m also gathering environmental data for cases of supercells that form in the Serranias del Burro for a small research project — mainly to document their environments, modes of development and motion, and the regimes that tend to bring such storms into the U.S. This is a concern for parts of South Texas because these storms often form well removed from others, in a very desolate part of another nation containing no storm spotters or chasers. “Del Burro” storms that have crossed the international border have been known to produce huge hail, flooding and tornadoes.

They also tend to be very interesting to observe remotely from 500 miles away! I’ve got ten total cases from the past three years so far, including the Bat-eating Supercell and one other storm that made it into the U.S. Most of these storms do stay in Mexico, doing who-knows-what out there in the semiarid scrubland of northern Coahuila.

Although these occurred before my data gathering project began, two of the most notorious border-crossing “Del Burro” storms also are in the Cool Image library: the supercell that caved in the Del Rio radar dome, and an absolutely brutal looking storm with an apparent tornado debris-ball in the hook echo, from March 2000. Clearly these “Made in Mexico” supercells are nothing to be taken lightly, and are long overdue for study…hence my little research project.

To this day I wonder what happened out in the remote Coahuilan cactus flats on that wild night of March 2000. Though I probably never can prove it, I’m convinced that the storm, for a short time on the Mexican side, must have been producing a violent tornado (see the gate-to-gate shear of at least 100 kt at 0.5 deg, while the debris ball was underway). For a couple of volume scans, the signatures were every bit as large and intense as anything in Oklahoma on May 3, 1999. Only after it weakened did it cross the border, and produce at least one tornado and baseball sized hail. Google Earth actually has very detailed imagery of some of the territory south and west of Ciudad Acuna, and there appears to be nothing but dirt, rocks, jeep trails and scrub brush out in the area of that apparent tornado.

I’ve long dreamed of someday observing Del Burro storms in person as they tear off the highlands and into the juicy boundary layers of the Rio Grande Valley. As long as the human situation remains as dangerous as it is on the Mexican side, however, it will have to remain a dream.



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