News DetailSupercells occurring in SW TX/Mexico Today!
Posted At: April 29, 2007 @ 3:34 PM
Posted By: Reed Timmer
Related Categories: Tornadoes
A cut-off storm system over the Southwest U.S. has resulted in favorable wind shear and instability for supercells over Southwest TX and extreme northeast Mexico west of Del Rio, TX. Given CAPEs of 1500-2000 J/kg, and marginal 0-1 km and 0-3 km helicity, the tornado threat will be minimal with these storms. However, if a storm can move along the southwest to northeast-oriented warm front, then the tornado threat will locally be enhanced.
The Midland radar is of 5:20 pm showed supercells just north I-10 in the Pecos Valley, with one cell tornado-warned at the time. Additional tornado warnings were associated with a storm near Abilene, TX as of 5:20 pm, but appeared to be weakening rapidly. The strongest supercells were located in extreme northeast Mexico west of Del Rio, TX, south of the "Big Bend". Three supercells were observed on Del Rio radar, with the northern storm showing a classic hook echo. The Midland (top) and Del Rio (bottom) radar images as of 5:20 are shown below:
The RUC analysis for CAPE at 2100 UTC shows a southwest to northeast-oriented warm front, with CAPEs to the southeast of the front in the 1500-2000+ j/kg range. The Del Rio and Abilene VAD wind profile shows good directional shear with height, but with only ~15 knot wind magnitudes at the low levels. For this reason, the 0-1 km helicities are not sufficient for large tornadoes. However, a supercell could produce a tornado as it passes over the warm front in southwest TX. The 4:00 pm CDT RUC analysis for CAPE and 0-1 km helicity are shown below:
CAPE:
0-1 KM HELICITY:
The Midland radar is of 5:20 pm showed supercells just north I-10 in the Pecos Valley, with one cell tornado-warned at the time. Additional tornado warnings were associated with a storm near Abilene, TX as of 5:20 pm, but appeared to be weakening rapidly. The strongest supercells were located in extreme northeast Mexico west of Del Rio, TX, south of the "Big Bend". Three supercells were observed on Del Rio radar, with the northern storm showing a classic hook echo. The Midland (top) and Del Rio (bottom) radar images as of 5:20 are shown below:
The RUC analysis for CAPE at 2100 UTC shows a southwest to northeast-oriented warm front, with CAPEs to the southeast of the front in the 1500-2000+ j/kg range. The Del Rio and Abilene VAD wind profile shows good directional shear with height, but with only ~15 knot wind magnitudes at the low levels. For this reason, the 0-1 km helicities are not sufficient for large tornadoes. However, a supercell could produce a tornado as it passes over the warm front in southwest TX. The 4:00 pm CDT RUC analysis for CAPE and 0-1 km helicity are shown below:
0-1 KM HELICITY:
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Nope, still don't understand helicity! Haha
All I know is red and purple spots are where these guys usually want to be.
Yikes....
Huge super cells over NE Mexico again heading in the general direction of Eagle Pass, Texas again.
http://www.wunderground.com/radar/radblast.asp?ID=DFX&lat=0&lon=0&label=you&type=N0R&zoommode=pan&map.x=400&map.y=240¢erx=574¢ery=130&prevzoom=zoom&num=1&delay=15&scale=0.550&noclutter=0&showstorms=0&showlabels=1&rainsnow=0&lightning=0
They deserve a break so I'm crossing my fingers.
Chris,
Helicity can be hard to understand even for meteorologists. Here is another explanation from the national weather service:
0-1 km Helicity - This is a derived parameter which quantifies the tendency for airflow in the layer from ground-level to a height of 1-kilometer (approximately 3300 feet above ground-level) to acquire rotation, and thus increase the potential for existing or future convective storms to develop mesoscale circulation's, possibly leading to tornado development. An assumption inherent in the helicity calculation is that any storms which form will move 30 degrees to the right of, and 75% of the magnitude of, the mean 0-6 kilometer wind flow (ground-level to approximately 20,000 feet above ground-level). This deviant storm motion is common with severe storms, and approximates "storm-relative" helicity. Helicity has units of energy and can therefore be interpreted as a measure of wind shear energy (directional wind shear). Helicity is depicted in units of m**2/s**2 (meters squared per second squared). If there is no directional wind shear, helicity will be zero. If the wind backs (turns counter-clockwise) with height then helicity will be negative, if wind veers (turns clockwise) with height then helicity will be positive. Helicity values are conditional - i.e. high values can occur without the necessary conditions to produce deep convection. Therefore, if helicity values are high, favorable atmospheric instability and lift must also be present in order to produce a threat for rotating storms. If convection occurs or is forecast (especially shallow convection or cells with small vertical extent; common along or ahead of Winter cold fronts, or within tropical cyclone outer rainbands), high values of 0-1 km helicity can be indicative of potential severe weather.
0-3 km Helicity - Same as 0-1 km Helicity (above), except for the 0-3 kilometer layer (ground-level to approximately 10,000 feet above ground-level). If convection occurs or is forecast (especially deep convection or cells with large vertical extent; common along or ahead of Spring cold fronts and some Winter cold fronts), high values of 0-3 km (storm-relative) helicity can be indicative of potential severe weather. A Study correlating the occurrence of tornadoes with 0-3 km (storm-relative) helicity in the Midwest found a value of 150 is the approximate threshold for supercell (persistent, rotating storms) development, especially when the 0-3 km (storm relative) inflow is 20 knots or greater. The following helicity versus tornado strength correlation's were also found:
Helicity = 150 to 299 = weak tornadoes (F0 and F1 on the Fujita scale)
Helicity = 300 to 499 = strong tornadoes (F2 and F3 on the Fujita scale)
Helicity = 450 or higher violent tornadoes (F4 and F5 on the Fujita scale)
I hope this helps. You may have to read this with Reed's explaination a few times.
Guys, Keep an eye on Del Rio, got a cell from mexico moving near the border in the next 30 minutes, passing a bit close to Eagle Pass.
Mexican Weather Service issued a tornado watch until 3:00 am for north coahuila. The supercell southwest Del Rio weakened but now its getting stronger.
The cell is defintily getting stronger, starting to rotate and getting a hook. About 25 miles from the Border, If it goes where its goign now, it will pass about 10 miles North of Eagle Pass. If starts Southwest, that isnt good.
It will be interesting to see what SAT issues this time.
Tornado touches down in Mexico!!
Carlos, Where are you getting this Information? Links Please! :)
Thanks for the info, I'll try to figure this out.
Contact with a guy in Mexican Weather Service
and the radar doppler says too.
http://www.wunderground.com/radar/radblast.asp?zoommode=zoom&num=1&delay=15&rbscale=0.1673913043478261&scale=1.000&noclutter=0&ID=DFX&type=N0R&lat=0&lon=0&label=you&showstorms=31&map.x=312.5&map.y=279.5¢erx=400¢ery=240&lightning=0&showlabels=1&rainsnow=0
Thanks!
Ok, This top just jumped to 53900! Wow.
Tornadovideos.net "Team B" has just jummped the border!!
Matt, what are you talking about? Im watching the mavs game and im a newbie lol. oh by the way.
GO MAVS!!!
Possible tornado will be near Piedras Negras/Eagle Pass in less than an hour.
I have a Question, ¿Eagle pass has tornado warning sirens?
Maybe mexican border city can hear it :S
TORNADO WARNING JUST ISSUED. INCLUDING PARTS OF MEXICO! TORNADO WARNING JUST NORTH OF EAGLE PASS
Carlos, No. And if they did, I dont think Eagle Pass has power restored from last weeks EF3
Fuck...they have no warning!!
Hope they have not another disaster. :(
Guys. Its turned SE, And its hooking. Eagle Pass is starting to get into the path of this thing.
That cell in Mexico is huge, looks like its making a right turn and the shear markers are saying 45 knots. Mexico and the TX Panhandle this year have been hot bed for tornadoes this year.
Fuck Fuck Fuck!! It will strike Piedras Negras if it still in the ground.
Eagle Pass is in line again for another monster storm. Sometimes you can't catch a break. Looks pretty nasty for those of us in Ohio on Tuesday.
HOok just formed. Top at 54000, VIL at 84. Still the warning is still for the north. This is BAD! ISSUE THE WARNING YOU NWS IDIOTS!
Looks like it should stay north of Eagle Pass right now.
David, the warning is issued for Maverick County.
JY, For 10 miles north of Eagle Pass. They just issued it for Northern eagle pass, It looks like North EG will get hit this time.
You can see the RFD on radar. Still really strong shear, but the it may becoming outflow dominant if the RFD moves out much further in front of the storm.
Agreed Wes...still projected to be north of EP.
VIL up to 90. Hook becoming more defined.
3 inch hail.. and more storms behind this one.
Hopefully those storms will move north... In the last 15 minutes this storm has had over 70 lightning strikes with just over 45% positive strikes! That's huge.
JY, that's the kind of storm I want to get pictures of at night! Sounds like it would make for amazing shots. Too bad we don't get that kind of storm here in Illinois/Indiana