

167 

WWUS20 KWNS 162038

SEL9

SPC WW 162038

ARZ000-OKZ000-TXZ000-170300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 589

NWS STORM PREDICTION CENTER NORMAN OK

335 PM CDT THU JUL 16 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF WESTERN AND SOUTHERN ARKANSAS

       SOUTHEAST OKLAHOMA

       FAR NORTHEAST TEXAS



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 335 PM UNTIL

1000 PM CDT.



HAIL TO 1.5 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 EITHER SIDE OF A LINE FROM 45 MILES SOUTH OF PINE

BLUFF ARKANSAS TO 10 MILES WEST NORTHWEST OF POTEAU OKLAHOMA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU9).



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 587...WW 588...



DISCUSSION...TSTMS ARE RAPIDLY DEVELOPING IN A HOT AND MOIST AIR

MASS WHERE MLCAPE HAS INCREASED TO 2500-3500 J/KG.  REGION REMAINS

ON SRN FRINGE OF STRONGER MID/HIGH-LEVEL WIND FIELDS AND RESULTANT

DEEP-LAYER SHEAR.  BUT...THE PRESENCE OF THE MODERATE TO STRONG

CONVECTIVE INSTABILITY SHOULD SUPPORT EVOLUTION OF A LARGE TSTM

CLUSTER WHICH WILL MOVE/PROPAGATE ALONG OUTFLOW BOUNDARY SITUATED

NW-SE ACROSS AREA.  THE PRIMARY SEVERE WEATHER THREATS WILL BE

DAMAGING WINDS AND HAIL.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 29035.





...MEAD/WEISS

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