Alert archive / Texas / Tornado Watches in 2007

Tornado Watch 169

April 23, 20077 counties in Texas

The Storm Prediction Center issued this tornado watch at Apr 23, 2007, 7:48 PM CDT for 7 counties in Texas. It was in force for 105 min.

The area

The outline as issued.

The facts

Issued: Apr 23, 2007, 7:48 PM CDT (00:48 UTC)
Expired: Apr 23, 2007, 9:33 PM CDT
In force: 105 min
Issued by: the Storm Prediction Center
Largest hail expected: 3 in
Strongest gust expected: 60 kt

Counties Edwards County, TX, Kinney County, TX, Maverick County, TX, Real County, TX, Uvalde County, TX, Val Verde County, TX, Zavala County, TX

The radar

The Laughlin AFB radar (KDFX), 43 km from the middle of the area, began a volume at 00:48 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: 30%
One or more EF2 to EF5 tornadoes: 30%
Ten or more severe wind reports: 20%
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: 50%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Apr 23, 8:01 PM CDT	Tornado Warning	EWX	Val Verde	29 min
Apr 23, 8:28 PM CDT	Tornado Warning	EWX	Val Verde	32 min
Apr 23, 8:41 PM CDT	Flash Flood Warning	EWX	Val Verde	2 hr
Apr 23, 8:49 PM CDT	Tornado Warning	EWX	Kinney	37 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

Del Rio, TX (KDRT), launched 00:00Z, 0.8 hours before the alert went out and 47 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: 1923 J/kg
Mixed-layer CIN: -157 J/kg
Mixed-layer LCL: 1353 m above ground
0-6 km bulk shear: 57 kt
0-1 km storm-relative helicity: 31 m²/s²
0-3 km storm-relative helicity: 89 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

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

000
WWUS20 KWNS 240049
SEL9  
SPC WW 240049
TXZ000-240400-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 169
NWS STORM PREDICTION CENTER NORMAN OK
750 PM CDT MON APR 23 2007

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

       SOUTHWEST TEXAS

EFFECTIVE THIS MONDAY EVENING FROM 750 PM UNTIL 1100 PM CDT.

TORNADOES...HAIL TO 3 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 45 STATUTE
MILES EAST AND WEST OF A LINE FROM 70 MILES NORTH NORTHEAST OF
DEL RIO TEXAS TO 75 MILES SOUTHEAST OF DEL RIO 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 165...WW 166...WW
167...WW 168...

DISCUSSION...SMALL BUT INTENSE AND POTENTIALLY TORNADIC SUPERCELL
JUST WEST OF DRT AT 01Z MAY CONTINUE EWD FOR A COUPLE MORE HOURS. 
OTHER DEVELOPMENT MAY OCCUR ACROSS WW THROUGH THE EVENING.  AIR MASS
IS VERY UNSTABLE AND STRONGLY SHEARED...SUGGESTING VERY LARGE HAIL
AND ISOLATED TORNADO THREAT WILL ACCOMPANY STRONGER CORES.  CAPPING
AND NOCTURNAL COOLING OF THE BOUNDARY LAYER MAY LIMIT EWD
DEVELOPMENT LATER THIS EVENING AND CONFINE MAIN THREAT NEARER THE
RIO GRANDE AND COUNTIES JUST EAST.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 27020.


...EVANS

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 23, 7:05 PM CDT	Mesoscale Discussion	SPC	Armstrong, Baylor, Borden, Briscoe, Callahan, Carson and 46 more	115 min
Apr 23, 9:17 PM CDT	Mesoscale Discussion	SPC	Kinney, Uvalde	118 min
Apr 23, 10:22 PM CDT	Mesoscale Discussion	SPC	Baylor, Callahan, Coke, Cottle, Crosby, Dickens and 18 more	83 min
Apr 24, 7:29 AM CDT	Mesoscale Discussion	SPC	Crockett, Glasscock, Irion, Reagan, Sterling, Upton	91 min
Apr 24, 11:23 AM CDT	Tornado Watch	SPC	Archer, Baylor, Clay, Wichita	9 hr
Apr 24, 11:28 AM CDT	Mesoscale Discussion	SPC	Archer, Baylor, Brown, Callahan, Clay, Coke and 33 more	2 hr
Apr 24, 11:49 AM CDT	Tornado Watch	SPC	Brown, Callahan, Coke, Coleman, Collin, Comanche and 35 more	11 hr
Apr 24, 12:40 PM CDT	Mesoscale Discussion	SPC	Bosque, Collin, Coryell, Dallas, Delta, Denton and 23 more	2 hr
Apr 24, 2:40 PM CDT	Tornado Watch	SPC	Bosque, Bowie, Camp, Cass, Delta, Ellis and 21 more	8 hr
Apr 24, 3:58 PM CDT	Tornado Watch PDS	SPC	Anderson, Bandera, Bell, Bexar, Blanco, Brown and 43 more	7 hr
Apr 24, 6:16 PM CDT	Mesoscale Discussion	SPC	Archer, Baylor, Clay, Wichita	119 min
Apr 24, 6:44 PM CDT	Mesoscale Discussion	SPC	Bandera, Bell, Bexar, Blanco, Bosque, Brown and 39 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.