WATCHES: Severe Thunderstorm Watch Number 313

WWUS20 KWNS 201731
SEL3
SPC WW 201731
TXZ000-210100-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 313
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT FRI MAY 20 2011

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

NORTHERN AND CENTRAL TEXAS

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 1230 PM UNTIL
800 PM CDT.

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

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 75
STATUTE MILES EAST AND WEST OF A LINE FROM 10 MILES EAST
NORTHEAST OF SHERMAN TEXAS TO 15 MILES SOUTH OF SAN ANTONIO
TEXAS. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED
WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR 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. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

OTHER WATCH INFORMATION...CONTINUE...WW 312...

DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND
INTENSITY THIS AFTERNOON ALONG COMPOSITE OUTFLOW/PACIFIC FRONT AS
REGION IS GLANCED BY VORTICITY MAXIMUM PIVOTING NNEWD FROM THE SRN
HIGH PLAINS. AMBIENT WARM SECTOR AIR MASS IS CHARACTERIZED BY A
VERY MOIST BOUNDARY LAYER BENEATH A STEEP MIDLEVEL LAPSE RATE
PLUME...YIELDING MLCAPE VALUES OF 2000-3500+ J/KG. REGION WILL
REMAIN ON SERN PERIPHERY OF STRONGER MID AND HIGH-LEVEL WIND FIELD
ATTENDANT TO ABOVE-MENTIONED VORTICITY MAXIMUM WITH SUFFICIENT
DEEP-LAYER SHEAR FOR ORGANIZED STORMS INCLUDING SUPERCELLS. WHILE A
BRIEF TORNADO IS POSSIBLE...LARGE HAIL AND LOCALLY DAMAGING WIND
GUSTS WILL BE THE PRIMARY HAZARDS.

AVIATION...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 500. MEAN STORM
MOTION VECTOR 25025.

...MEAD

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