

489 

WWUS20 KWNS 182125

SEL0

SPC WW 182125

ARZ000-KSZ000-MOZ000-OKZ000-190500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 170

NWS STORM PREDICTION CENTER NORMAN OK

425 PM CDT SAT APR 18 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHWEST ARKANSAS

       SOUTHEAST KANSAS

       SOUTHWEST MISSOURI

       NORTHEAST OKLAHOMA



EFFECTIVE THIS SATURDAY AFTERNOON FROM 425 PM UNTIL MIDNIGHT 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 85

STATUTE MILES EAST AND WEST OF A LINE FROM 45 MILES NORTH

NORTHEAST OF CHANUTE KANSAS TO 30 MILES SOUTH SOUTHEAST OF POTEAU

OKLAHOMA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0).



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 166...WW 167...WW

168...WW 169...



DISCUSSION...THUNDERSTORMS EXPECTED TO INCREASE IN NUMBER AND

INTENSITY ACROSS WATCH AREA THRU THE EVENING AS UPPER TROUGH

APPROACHES. STEEP...COOL LAPSE RATES IN PLACE COUPLED A

MOIST/UNSTABLE AIR MASS WILL BE CONDUCIVE TO LARGE HAIL IN MANY

STORMS.  SUFFICIENT SHEAR FOR ROTATING STORMS BY EVENING AS UPPER

TROUGH APPROACHES. SOME OF AREA WILL BE MONITORED FOR POSSIBLE

UPGRADE TO TORNADO WATCH IF THESE CONDITIONS DEVELOP



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 450. MEAN STORM

MOTION VECTOR 24025.





...HALES

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