WATCHES: Severe Thunderstorm Watch Number 854

WWUS20 KWNS 182243
SEL4
SPC WW 182243
ARZ000-OKZ000-TXZ000-190600-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 854
NWS STORM PREDICTION CENTER NORMAN OK
545 PM CDT SUN SEP 18 2011

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

WESTERN AND CENTRAL ARKANSAS
FAR SOUTHEAST OKLAHOMA
FAR NORTHEAST TEXAS

EFFECTIVE THIS SUNDAY AFTERNOON AND MONDAY MORNING FROM 545 PM
UNTIL 100 AM 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 55
STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES EAST OF PARIS
TEXAS TO 15 MILES WEST NORTHWEST OF RUSSELLVILLE ARKANSAS. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU4).

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 852...WW 853...

DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND
INTENSITY THIS EVENING AS FORCING FOR ASCENT ATTENDANT TO
PROGRESSIVE MIDLEVEL TROUGH ACTS ON A MOIST AND MODERATELY UNSTABLE
AIR MASS WITH MLCAPE VALUES OF 1000-2000 J/KG. THOUGH MID- AND
HIGH-LEVEL FLOW IS NOT PARTICULARLY STRONG...BACKED LOW-LEVEL WINDS
INVOF WEAK WARM FRONT FROM E-CNTRL OK INTO S-CNTRL AR WILL ENHANCE
DEEP-LAYER SHEAR WITH SETUP SUPPORTIVE OF SUPERCELLS CAPABLE OF
LARGE HAIL AND DAMAGING WIND GUSTS.

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 25020.

...MEAD

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