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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1. JeffM 2:15 PM GMT on April 25, 2007
Was pretty rough here in San Antonio last night as well. Member Since: August 19, 2005 Posts: 0 Comments: 137

2. hurricane23 2:16 PM GMT on April 25, 2007
Great stuff DR.Masters... Thanks for the blog and great new animation feature. Member Since: May 14, 2006 Posts: 8 Comments: 13274

3. Tazmanian 2:18 PM GMT on April 25, 2007
WU e mail for dr m e mail me thanks Member Since: May 21, 2006 Posts: 5088 Comments: 111313

4. hurricane23 2:20 PM GMT on April 25, 2007
Incredible hook ocho. Member Since: May 14, 2006 Posts: 8 Comments: 13274

5. StormJunkie 2:24 PM GMT on April 25, 2007
Thanks Dr M. One of my coworkers has family in Eagle Pass. Thankfully they were all ok. Did have monetary damage, but in the whole scheme of things that is no big deal! Member Since: August 17, 2005 Posts: 26 Comments: 15218

6. thisisfurious 2:28 PM GMT on April 25, 2007
I am in awe regarding the powerful weather systems we have seen this spring. It's nothing to take lightly, for sure. I had no idea that May and June are the peak months (I have never lived in an area with consistent tornado threats) because with all of the recent activity, I thought we were in the clutch of the worst right now. As far as my weather (Miami), we have been dry as a bone. I finally see some cloud activity in the GOM - can anyone surmise as to whether or not we might get some moisture from this? It looks like it has a bit of potential, but I am still confused regarding the height of the clouds and what they mean.

7. Levi32 2:33 PM GMT on April 25, 2007
Thanks Dr. Masters. I couldn't help but notice that you put the size of the tornado animation at 300MB. Now with DSL that would load in 4 hours lol. I think you meant Kb. Might draw more clicks to that link if the size wasn't so menacing lol. Thanks for the great update, sad so many people have died. Member Since: November 24, 2005 Posts: 586 Comments: 25441

8. CrazyC83 2:45 PM GMT on April 25, 2007
Actually, the other High Risk was not February 2, but April 13 (that one busted even though a stray tornado killed one near Fort Worth). Eagle Pass was outside the High Risk area as well; it was mostly wind damage in that area. Of the 17 killer tornadoes so far this year, six took place in High Risk areas (killing 20), six in Moderate Risk areas (killing 14) and five in Slight Risk areas (killing 26). Member Since: September 19, 2005 Posts: 0 Comments: 142

9. MisterPerfect 3:08 PM GMT on April 25, 2007
Posted By: thisisfurious at 2:28 PM GMT on April 25, 2007. As far as my weather (Miami), we have been dry as a bone. I finally see some cloud activity in the GOM - can anyone surmise as to whether or not we might get some moisture from this? It looks like it has a bit of potential, but I am still confused regarding the height of the clouds and what they mean. The forecast is for SLIGHT chances of showers over the weekend in South Florida. SLIGHT means HECK NO, I'LL BE AT VENETIAN POOL IF YOU NEED ME in Miamian. Member Since: November 1, 2006 Posts: 69 Comments: 19467

10. Inyo 3:25 PM GMT on April 25, 2007
I happened to see that storm yesterday on the radar just when it was crossing the border, and it was pretty obviously doing something nasty. What a distinct hook echo! Member Since: September 3, 2002 Posts: 42 Comments: 765

11. cudasistah 3:31 PM GMT on April 25, 2007
Thanks Dr. M. Sad and scary weather happenings this year so far. Makes me more than a little nervous for season upcoming. LRandyB said it best though in a toast the other night, "Here is to a season full of Cat 5's, with no landfalls." We all of course agreed :-)

12. hurricane23 3:37 PM GMT on April 25, 2007
The forecast is for SLIGHT chances of showers over the weekend in South Florida. SLIGHT means HECK NO, I'LL BE AT VENETIAN POOL IF YOU NEED ME in Miamian. LOL!0 chance is correct...Very dry air in place over south florida during the next 3-5 days with slight chance maybe a 20-30 percent chance of precip. Also look for temps to be in the upper 80's this weekend. Member Since: May 14, 2006 Posts: 8 Comments: 13274

15. Tazmanian 3:57 PM GMT on April 25, 2007
neutral or La Nina for this year? Member Since: May 21, 2006 Posts: 5088 Comments: 111313

16. thisisfurious 4:00 PM GMT on April 25, 2007
I guess its about time that I try out that Venetian Pool that I have been hearing about... I only work 2 miles from it, but I have never gone! I used to live in the desert... Miami is starting to feel similar.

17. lilmax 4:01 PM GMT on April 25, 2007
Yup, i feel bad for those folks affected by the tornado. Thanks Dr. M.

18. Dr. Jeff Masters, Director of Meteorology (Admin) 4:03 PM GMT on April 25, 2007
CrazyC83 wrote: Actually, the other High Risk was not February 2, but April 13 (that one busted even though a stray tornado killed one near Fort Worth). Eagle Pass was outside the High Risk area as well; it was mostly wind damage in that area. Of the 17 killer tornadoes so far this year, six took place in High Risk areas (killing 20), six in Moderate Risk areas (killing 14) and five in Slight Risk areas (killing 26). Thanks, I dropped the Feb 2 mention, I wasn't sure if I was remembering that one correctly. Jeff Masters

19. Tazmanian 4:06 PM GMT on April 25, 2007
what is evere one take on for this hurricane year neutral or La Nina for this year? Member Since: May 21, 2006 Posts: 5088 Comments: 111313

20. Tazmanian 4:09 PM GMT on April 25, 2007
and they had a PDS watch boxs too at the time Member Since: May 21, 2006 Posts: 5088 Comments: 111313

21. thelmores 4:10 PM GMT on April 25, 2007
I realize there is not necessarily a direct correlation, but is there any evidence that an active year for tornado's may mean an active year for hurricanes?? just curious if there is any evidence, or merely coincidence? as I stated yesterday, tornado's are the ultimate in terror.... feel for those in tornado prone area's! Member Since: September 8, 2005 Posts: 0 Comments: 3748

22. Tazmanian 4:14 PM GMT on April 25, 2007
TORNADO WATCH NUMBER 179 NWS STORM PREDICTION CENTER NORMAN OK 400 PM CDT TUE APR 24 2007 THE NWS STORM PREDICTION CENTER HAS ISSUED A TORNADO WATCH FOR PORTIONS OF CENTRAL AND SOUTHERN TEXAS EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 400 PM UNTIL 1100 PM CDT. ...THIS IS A PARTICULARLY DANGEROUS SITUATION... DESTRUCTIVE TORNADOES...LARGE HAIL TO 3.5 INCHES IN DIAMETER... THUNDERSTORM WIND GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 115 STATUTE MILES EAST AND WEST OF A LINE FROM 55 MILES SOUTH SOUTHWEST OF DEL RIO TEXAS TO 30 MILES NORTHWEST OF WACO TEXAS. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9). REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. OTHER WATCH INFORMATION...CONTINUE...WW 172...WW 173...WW 174...WW 175...WW 176...WW 177...WW 178... DISCUSSION...SUPERCELLS WITH AN ATTENDANT THREAT FOR VERY LARGE HAIL...HIGH WIND AND POSSIBLY A STRONG TORNADO OR TWO...WILL DEVELOP OVER THE CNTRL/S TX AREA THROUGH THIS EVENING. CONTINUED SFC HEATING...RICH MOISTURE INFLOW AND ARRIVAL OF SW TX UPR DISTURBANCE SHOULD CREATE FAVORABLE ENVIRONMENT FOR A FEW LONG-LIVED STORMS...ESPECIALLY ALONG WSW/ENE AXIS OVER CNTRL TX ALONG SRN FRINGE OF STORMS THAT FORMED EARLIER IN THE DAY. AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 3.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM MOTION VECTOR 24035. her is watch 179 Member Since: May 21, 2006 Posts: 5088 Comments: 111313

23. thelmores 4:29 PM GMT on April 25, 2007
Taz, you do realize that was yesterday's watch, right?? Member Since: September 8, 2005 Posts: 0 Comments: 3748

24. Tazmanian 4:32 PM GMT on April 25, 2007
LOL i no that Member Since: May 21, 2006 Posts: 5088 Comments: 111313

25. hurricane23 4:53 PM GMT on April 25, 2007
Hey stormw i sent you and email... Member Since: May 14, 2006 Posts: 8 Comments: 13274

26. thelmores 4:54 PM GMT on April 25, 2007
Just checking friend! So you were just pointing out what the forecast was yesterday, before the Eagle Pass event? If you would have posted this yesterday, I would have been more impressed! :D Member Since: September 8, 2005 Posts: 0 Comments: 3748

27. Inyo 5:44 PM GMT on April 25, 2007
someone did post it yesterday! i forget who, but it might have been Taz Member Since: September 3, 2002 Posts: 42 Comments: 765

28. weatherboykris 6:15 PM GMT on April 25, 2007
hello Member Since: December 9, 2006 Posts: 125 Comments: 11343

29. thelmores 6:16 PM GMT on April 25, 2007
In that case, I am impressed! :) Great weather minds around here! Yes Taz, you are included! ;) Member Since: September 8, 2005 Posts: 0 Comments: 3748

30. weatherboykris 6:21 PM GMT on April 25, 2007
Posted By: thelmores at 4:10 PM GMT on April 25, 2007. I realize there is not necessarily a direct correlation, but is there any evidence that an active year for tornado's may mean an active year for hurricanes?? just curious if there is any evidence, or merely coincidence? as I stated yesterday, tornado's are the ultimate in terror.... feel for those in tornado prone area's! It depends. Member Since: December 9, 2006 Posts: 125 Comments: 11343

31. weatherboykris 6:25 PM GMT on April 25, 2007
If anything,there appears to be an inverse relationship between early tornado season activity and hurricane activity. Member Since: December 9, 2006 Posts: 125 Comments: 11343

33. chessrascal 7:00 PM GMT on April 25, 2007
guess no one is on

34. H2PV 7:15 PM GMT on April 25, 2007
Posted By: thelmores at 4:10 PM GMT on April 25, 2007. I realize there is not necessarily a direct correlation, but is there any evidence that an active year for tornado's may mean an active year for hurricanes?? 2004 was an hyperactive year for both hurricanes and tornadoes. However it was the hurricane-spawned tornadoes from Ivan and Frances that pushed it over the top as the all time record year for tornadoes. The 509 tornadoes that came in May 2004 helped push the total up to 1819 tornadoes for the year. May of 2003 was the record breaker for most tornadoes in May with 562 that came in swarms up to 100 at a time. http://groups.google.com/group/sci.geo.meteorology/ http://www.guardian.co.uk/gall/0,8542,950314,00.html 2003 was also a hyperactive year for Atlantic Hurricanes.

35. H2PV 7:20 PM GMT on April 25, 2007
Posted By: weatherboykris at 6:25 PM GMT on April 25, 2007. If anything,there appears to be an inverse relationship between early tornado season activity and hurricane activity. Not in 2003, 2004, or 2005, according to this page... http://www.spc.noaa.gov/climo/torn/monthlytornstats.html

37. dewfree 7:35 PM GMT on April 25, 2007
This d a gppd day doesnt have anything to do with thie blog right as of now but; thier is a april huricanes forecast of 17 named storms 5 major 3,4,5 chances of a hit is 140% this season humm probably gulf state east side fl ' have a good day !! dew Member Since: August 27, 2006 Posts: 7 Comments: 589

38. Inyo 8:10 PM GMT on April 25, 2007
you can't have more than an 100% chance of a hurricane strike! Member Since: September 3, 2002 Posts: 42 Comments: 765

41. Tazmanian 11:24 PM GMT on April 25, 2007
Link Member Since: May 21, 2006 Posts: 5088 Comments: 111313

42. KEEPEROFTHEGATE (Mod) 12:19 AM GMT on April 26, 2007
T-MINUS 843HRS 40MINS TO HURRICANE SEASON Member Since: July 15, 2006 Posts: 143 Comments: 40383

43. DocNDswamp 12:30 AM GMT on April 26, 2007
Hi Dr Jeff, Excellent report... Thought you and fellow weather enthusiasts might find this vis satellite view of that supercell interesting... Obtained imagery from Texas Commission on Environmental Quality (only maintain a 24 hr archive), cropped and adjusted color / contrast in Photoshop, otherwise as original... Wow, what a monster! ... This rogue cell was another classic "right-mover", tracking more due east than NNE of storms along the previous squall line... (last night's GFS 0Z view of atmospheric levels from initiation period shows the evolving dynamics well and the secondary low pressure area it formed within)... In the sat imagery it almost appears one can see the vortex, although that eye-like center may not be in reality... Condolences to those who lost lives / property there from this historic storm... With all the sparsely populated areas nearby, sad this one found a target... As the MCS continued into San Antonio after midnight this morning, copied barometric pressure data from numerous stations there, indicating a rapid BP spike range of .16" to .20" (inHg) / 5.42 mb to 6.77 mb (i.e. at KSAT, jumped from 29.79" to 29.95") within 30 minutes from powerful gust front / downdrafts... with sharpest jump of near 3-4 mb occurring in under 10 minutes... BP then fell back under the broader synoptic low pressure of the storm system as transient effects of MCS's mesohigh abated... The phenomena can be viewed from San Antonio airport's charts (KSAT)... Amazing number of deadly severe storms we've seen this winter / spring... Member Since: September 21, 2005 Posts: 92 Comments: 4638

44. StormJunkie 12:31 AM GMT on April 26, 2007
T-MINUS 843HRS 40MINS TO HURRICANE SEASON...Are you kidding me...lol That is a good one Keeper! Evening JF, SSIG, Taz an Inyo, good to see everyone! Member Since: August 17, 2005 Posts: 26 Comments: 15218

45. StormJunkie 12:33 AM GMT on April 26, 2007
Evening Doc, good to see ya and great pic! Member Since: August 17, 2005 Posts: 26 Comments: 15218

46. DocNDswamp 12:41 AM GMT on April 26, 2007
Hey SJ! Yeah I was digging around and copying storm data earlier today when came across those images... Less than 4 hrs before that image, there was nothing in sight! ...LOL, nothing visible, ...just a ton of potential about to happen! Member Since: September 21, 2005 Posts: 92 Comments: 4638

47. weathermanwannabe 2:31 AM GMT on April 26, 2007
How are any of our people out in Texas and Louisiana? Member Since: August 8, 2006 Posts: 0 Comments: 6675

48. MastaSki06 8:39 AM GMT on April 26, 2007
Great read Dr. Masters. Like a few others I noticed this particular storm as it was happening. At that time it had a top of 51,000 feet. with 4+ inch hail. I pray for those affected. Member Since: September 19, 2005 Posts: 5 Comments: 146

50. MissBennet 1:00 PM GMT on April 26, 2007
Not much happened in Louisiana, at least in New Orleans. I slept through most of it. Woke up only a couple times when the rain pounded especially hard on my windows. Then again, I was so tired that I could have slept through a freight train going by. :)

51. catastropheadjuster 1:07 PM GMT on April 26, 2007
Well here in Chickasaw,Al right outside of Mobile It's getting black and starting to rain. Member Since: August 24, 2006 Posts: 21 Comments: 3556

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