Alert archive / Texas / Tornado Watches in 2007

Tornado Watch 57

March 11, 200719 counties in Texas

The Storm Prediction Center issued this tornado watch at Mar 11, 2007, 1:58 PM CDT for 19 counties in Texas. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Mar 11, 2007, 1:58 PM CDT (18:58 UTC)
Expired: Mar 11, 2007, 9:00 PM CDT
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

Counties Brewster County, TX, Coke County, TX, Crane County, TX, Crockett County, TX, Edwards County, TX, Irion County, TX, Kimble County, TX, Kinney County, TX, Menard County, TX, Pecos County, TX, Reagan County, TX, Real County, TX, Schleicher County, TX, Sterling County, TX, Sutton County, TX, Terrell County, TX, Tom Green County, TX, Upton County, TX, Val Verde County, TX

The radar

The Midland/Odessa radar (KMAF), 130 km from the middle of the area, began a volume at 19:02 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 40%
One or more EF2 to EF5 tornadoes: 20%
Ten or more severe wind reports: 30%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 40%
One or more hailstones of 2 inches or more: 30%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

12 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Mar 11, 3:16 PM CDT	Severe Thunderstorm Warning	MAF	Pecos	59 min
Mar 11, 3:55 PM CDT	Severe Thunderstorm Warning	MAF	Terrell	65 min
Mar 11, 4:07 PM CDT	Severe Thunderstorm Warning	SJT	Sterling	38 min
Mar 11, 4:10 PM CDT	Severe Thunderstorm Warning	MAF	Pecos	65 min
Mar 11, 4:35 PM CDT	Tornado Warning	MAF	Pecos	55 min
Mar 11, 4:42 PM CDT	Severe Thunderstorm Warning	SJT	Sterling	48 min
Mar 11, 4:57 PM CDT	Severe Thunderstorm Warning	MAF	Upton	40 min
Mar 11, 4:57 PM CDT	Severe Thunderstorm Warning	MAF	Terrell	63 min
Mar 11, 5:07 PM CDT	Severe Thunderstorm Warning	SJT	Coke, Nolan, Sterling	38 min
Mar 11, 5:20 PM CDT	Tornado Warning	SJT	Coke, Sterling	40 min
Mar 11, 5:54 PM CDT	Severe Thunderstorm Warning	SJT	Coke, Runnels, Tom Green	51 min
Mar 11, 6:26 PM CDT	Severe Thunderstorm Warning	SJT	Concho, McCulloch, Menard	20 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Midland Regional, TX (KMAF), launched 12:00Z, 7.0 hours before the alert went out and 131 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 1106 J/kg
Mixed-layer CIN: -124 J/kg
Mixed-layer LCL: 862 m above ground
0-6 km bulk shear: 50 kt
0-1 km storm-relative helicity: 137 m²/s²
0-3 km storm-relative helicity: 165 m²/s²
Significant tornado parameter: 0.5
Supercell composite: 1.8

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000
WWUS20 KWNS 111857
SEL7  
SPC WW 111857
TXZ000-120200-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 57
NWS STORM PREDICTION CENTER NORMAN OK
200 PM CDT SUN MAR 11 2007

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF 

       SOUTHWEST TEXAS

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 200 PM UNTIL 900
PM CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 85 STATUTE
MILES EAST AND WEST OF A LINE FROM 75 MILES WEST NORTHWEST OF SAN
ANGELO TEXAS TO 20 MILES WEST OF DEL RIO TEXAS.  FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU7).

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.

DISCUSSION...GRADUAL CLEARING IS OCCURRING ACROSS SOUTHWEST
TX...ALLOWING AIRMASS TO SLOWLY DESTABILIZE AND CAP TO WEAKEN. 
ISOLATED THUNDERSTORMS ARE EXPECTED TO DEVELOP IN THE NEXT COUPLE OF
HOURS OVER THE MOUNTAINS WEST AND SPREAD EASTWARD INTO WATCH AREA. 
INCREASING MOISTURE VALUES...COUPLED WITH SUFFICIENT LOW AND DEEP
LAYER VERTICAL SHEAR...WILL PROMOTE SUPERCELLS CAPABLE OF LARGE
HAIL...DAMAGING WINDS...AND ISOLATED TORNADOES.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
450. MEAN STORM MOTION VECTOR 28030.


...HART

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 11, 3:29 AM CDT	Mesoscale Discussion	SPC	Clay, Wichita, Wilbarger	91 min
Mar 11, 10:18 AM CDT	Mesoscale Discussion	SPC	Borden, Coke, Dawson, Garza, Glasscock, Howard and 13 more	87 min
Mar 11, 2:25 PM CDT	Mesoscale Discussion	SPC	Archer, Clay, Collin, Cooke, Denton, Fannin and 10 more	95 min
Mar 11, 4:50 PM CDT	Mesoscale Discussion	SPC	Bandera, Bell, Bexar, Blanco, Bosque, Brown and 33 more	85 min
Mar 11, 5:16 PM CDT	Tornado Watch	SPC	Atascosa, Bandera, Bell, Bexar, Blanco, Brown and 37 more	8 hr
Mar 11, 5:27 PM CDT	Mesoscale Discussion	SPC	Concho, Crockett, Edwards, Irion, Kimble, Menard and 7 more	2 hr

Nearby

Tornado Watches in Texas, 2007 Every tornado watch in 2007

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.