

850 

WWUS20 KWNS 182037

SEL2

SPC WW 182037

ARZ000-MOZ000-OKZ000-190400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 852

NWS STORM PREDICTION CENTER NORMAN OK

330 PM CDT SUN SEP 18 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN ARKANSAS

       SOUTHWEST MISSOURI

       EASTERN AND SOUTHERN OKLAHOMA



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 330 PM UNTIL

1100 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 60

STATUTE MILES EAST AND WEST OF A LINE FROM 10 MILES NORTHWEST OF

MONETT MISSOURI TO 10 MILES SOUTHWEST OF DURANT OKLAHOMA.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU2).



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.



DISCUSSION...TSTMS EXPECTED TO INCREASE/DEVELOP OVER THE NEXT OUR OR

SO IN CONFLUENT LOW LVL FLOW AHEAD OF COLD FRONT NOW CROSSING CNTRL

OK...IN RESPONSE TO BOTH SFC HEATING AND ASCENT WITH LEADING EDGE OF

APPROACHING VORT LOBE IN LARGER SCALE UPR TROUGH.  OBSERVED AND FCST

WIND FIELDS SUGGEST LIKELIHOOD FOR A FEW SUSTAINED STORMS AND

POSSIBLY A COUPLE SUPERCELLS WITHIN THE BANDS/SMALL CLUSTERS THAT

LIKELY WILL EVOLVE LATER TODAY.  WITH SBCAPE OF 1500-2500 J/KG AND

RICH LOW LVL MOISTURE...POTENTIAL WILL EXIST FOR SVR HAIL AND WIND.

A TORNADO CANNOT BE RULED OUT IN FAR ERN OK/WRN AR...WHERE NEAR-SFC

FLOW WILL REMAIN SLIGHTLY BACKED BY FRICTION.  BUT ABSENCE OF

BETTER-DEFINED SFC WAVE...OPEN NATURE OF UPR TROUGH...AND MODEST LOW

LVL WINDS SUGGEST THAT ANY SUCH THREAT SHOULD REMAIN ISOLD.



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 26025.





...CORFIDI

