Dr. Jeff Masters' WunderBlog

Killer tornado hits Texas and Mexico

Posted by: Dr. Jeff Masters, 2:14 PM GMT on April 25, 2007

A killer tornado swept through Piedras Negras, Mexico, crossed the Rio Grande River, and brought devastation to the small town of Eagle Pass, Texas, at about 7pm CDT last night. The tornado killed three and injured 87 in Mexico; seven died in Texas, and 74 were injured. Five of the U.S. deaths occurred in a single mobile home when it was picked up and tossed into an elementary school. The tornado destroyed 20 homes, two schools, and the local sewage treatment plant in Eagle Pass. Killer tornadoes in Mexico are rare, as most of the country is too far south to get tornado weather, and is sparsely populated in the Texas border regions that are prone to tornadoes. Mexico's worst tornado that I could find record of occurred in 2004, when a tornado killed 32 in Piedras Negras.

Tornadoes were also reported last night in Oklahoma, Kansas, and eastern Colorado. More tornadoes are possible today, as the Storm Prediction Center (SPC) has placed much of the Mississippi Valley under it's "Slight Risk" area. This is a major step down from yesterday's risk level, though, when SPC had portions of Texas under its "High Risk" area (although Eagle Pass was in the "Moderate Risk" area). This is the third time in 2007 that SPC issued a "High Risk" forecast. A "High Risk" forecast was also issued for the EF4 March 1 Enterprise, Alabama tornado that killed 20. It's been a bad year for tornadoes--last night's storm brought the 2007 U.S. death toll to 59. The average tornado death toll for the entire year has been just 46 the past three years. It's only April, and we still have the peak tornado months of May and June to get through.

Figure 1. Radar reflectivity image of the April 24, 2007 tornado as it approached Eagle Pass, Texas. Note the distinctive hook shape of the radar echo, which is characteristic of supercell thunderstorms that spawn strong tornadoes.

Figure 2. Radar velocity image of the April 24, 2007 tornado as it approached Eagle Pass, Texas. Note the area of blue and red echoes just south of the circle with a "+" inside it that marks the location of Eagle Pass. The blues and reds show that strong winds going both towards and away from the radar exist in a small area, denoting the presence of a parent mesocyclone (rotating thunderstorm) and a tornado.

Figure 3. Vertically integrated Liquid Water (VIL), in kilograms per square meter, for the April 24, 2007 tornado as it approached Eagle Pass, Texas. VIL is a measure of how much water is in the storm, when measured from the surface to the top of the storm. The Eagle Pass thunderstorm had cloud tops at 56,000 feet, so a column of air one meter square extending from the surface to 56,000 feet had up to 70 kilograms of liquid water in it. That's a lot of water available for hailstones to grow in, and large hail up to 1.75 inches in diameter was observed with this storm. A VIL of at least 50 is typically required to get large hail two inches in diameter in April in the Plains. A VIL of about 65 is needed later in summer, when the thunderstorms grow taller and more liquid water is needed to make large hail. See the Oklahoma Climatological Survey VIL help page for more information.

We've saved a 300 Mb radar animation of the Eagle Pass tornado for those interested.

Jeff Masters

T-3 (Photo5150)

A Tornado crosses the 283 west of Laverne Oklahoma during a severe thunder storms passing through the great plains late monday night April 23,2007�Photo by Gene Blevins/LA Daily News�

TORNADO!! (kshippychic)

My first time seeing a tornado - I cannot tell you how fun this was. I never got to see one actually touch down, but I saw so many just finger up and down out of the clouds!! It was just amazing. Thes were taken just east of Nickerson, Kansas!

Categories: Tornado

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251. dewfree 9:25 AM GMT on April 27, 2007
may even be a good year for Shouth America to get in on a Huricane this time around keep watch out and we'll see !! Member Since: August 27, 2006 Posts: 7 Comments: 589

252. dewfree 9:44 AM GMT on April 27, 2007
If La nino event comes in three mounths from now as predicted i believe it will transend into Oct Huricanes effecting the continental US on the lower half of corse like isaid earlier . but cant rule out a southeastern event though unlikely at this time . eastern mexico and the gulf a great area of intrest if the NAO continues in its curent pattern .watch for the change in NAO .tht will be the diffrence in a hard charging la nino or a week at best just rain events from tropical systems this year .im gone now back in two weeks to up date my ideas on the issue and as far as the tornadoes in TX well they have been thier ever sence i have been here so isnt anything new to me .The mexico thing is though and i'll keep watchig the develping year have a good bye Member Since: August 27, 2006 Posts: 7 Comments: 589

253. StoryOfTheCane 11:15 AM GMT on April 27, 2007
This area is pretty active, once conditions are stable look out

254. chessrascal 12:42 PM GMT on April 27, 2007
latest quickscat

255. MisterPerfect 12:45 PM GMT on April 27, 2007
Stop slacking and update your blog Dr. M. Member Since: November 1, 2006 Posts: 69 Comments: 19470

256. kmanislander 1:31 PM GMT on April 27, 2007
We had better hope that this pattern does not persist through the season. Member Since: August 19, 2006 Posts: 0 Comments: 14988

257. kmanislander 1:38 PM GMT on April 27, 2007
Tried loading the ATL wind field and surface map. Big high stretching all the way across the ATL. Looks like the 2004 set up. Also noticed that the 8:05 Caribbean discussion referred to a 1008 mb low over N Colombia near 10 N 94 W !! I think they must mean 74 W This low may be responsible for the showers in the S Caribbean Member Since: August 19, 2006 Posts: 0 Comments: 14988

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