

450 

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

