Tornado Watch 271

Issued

May 10, 2012, 11:40 AM CDT (16:40 UTC)

Expired

May 10, 2012, 8:00 PM CDT

In force

8 hr

Issued by

the Storm Prediction Center

Largest hail expected

3 in

Strongest gust expected

60 kt

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

60%

One or more hailstones of 2 inches or more

60%

Six or more combined severe hail and wind reports

80%

• Mesoscale Discussion 773May 10, 9:51 AM CDT
• Mesoscale Discussion 776May 10, 2:07 PM CDT
• Mesoscale Discussion 777May 10, 3:04 PM CDT
• Mesoscale Discussion 780May 10, 5:43 PM CDT
• Mesoscale Discussion 781May 10, 7:18 PM CDT

331 
WWUS20 KWNS 101645
SEL1
SPC WW 101645
TXZ000-CWZ000-110100-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 271
NWS STORM PREDICTION CENTER NORMAN OK
1140 AM CDT THU MAY 10 2012

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

       SOUTH-CENTRAL AND DEEP SOUTH TEXAS
       COASTAL WATERS

EFFECTIVE THIS THURSDAY MORNING AND EVENING FROM 1140 AM UNTIL
800 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 75 STATUTE
MILES EAST AND WEST OF A LINE FROM 55 MILES NORTHEAST OF COTULLA
TEXAS TO 25 MILES EAST SOUTHEAST OF MCALLEN TEXAS.  FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU1).

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 270...

DISCUSSION...TSTMS /INCLUDING SUPERCELLS/ ARE ONGOING AS OF LATE
MORNING INVOF A STATIONARY BOUNDARY WHICH EXTENDS FROM N OF LRD TO
NEAR OR JUST S OF PSX.  AIR MASS ALONG AND S OF THIS BAROCLINIC ZONE
IS QUITE MOIST WITH DEWPOINTS IN THE UPPER 60S-LOWER 70S.  WHEN
COUPLED WITH DAYTIME HEATING AND STEEP MIDLEVEL LAPSE RATES...EXPECT
ENVIRONMENT TO BECOME MODERATE-STRONGLY UNSTABLE BY AFTERNOON WITH
MLCAPE APPROACHING 1500-3000 J/KG.  THIS INSTABILITY WILL ALIGN WITH
A STEADILY STRENGTHENING DEEP-LAYER WIND FIELD /AND VERTICAL SHEAR/
OWING TO THE EWD-DEVELOPMENT OF MID AND UPPER-LEVEL JET STREAKS
ACROSS THE LOWER RIO GRANDE VALLEY.  AS SUCH...SETUP IS EXPECTED TO
BECOME INCREASINGLY SUPPORTIVE OF INTENSE SUPERCELLS CAPABLE OF VERY
LARGE HAIL...TORNADOES...AND DAMAGING WINDS.

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
550. MEAN STORM MOTION VECTOR 27030.


...MEAD

Tornado Watches in Texas, 2012Every tornado watch in 2012

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.