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WWUS20 KWNS 221919

SEL2

SPC WW 221919

MTZ000-SDZ000-WYZ000-230200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 382

NWS STORM PREDICTION CENTER NORMAN OK

120 PM MDT TUE JUN 22 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF SOUTHEAST MONTANA

       PARTS OF WESTERN SOUTH DAKOTA

       MUCH OF CENTRAL AND NORTH WYOMING



EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 120 PM UNTIL

800 PM MDT.



HAIL TO 3 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 105

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 50 MILES NORTH

NORTHWEST OF RIVERTON WYOMING TO 70 MILES SOUTH OF LEMMON SOUTH

DAKOTA.  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.



OTHER WATCH INFORMATION...CONTINUE...WW 381...



DISCUSSION...IMPRESSIVE S/WV TROUGH AND STRONG MID/UPPER WIND MAX

MOVING EWD ACROSS WRN WY SUPPORTING DEVELOPMENT OF INCREASING

THUNDERSTORM ACTIVITY FROM W TO E ACROSS THE WATCH. STEEP LAPSE

RATES AND MLCAPES AOA 1200 J/KG COUPLED WITH 50KT OF DEEP LAYER

SHEAR EXPECTED TO LEAD TO SUPERCELL FORMATION...PARTICULARLY ERN WY

INTO WRN SD.  VERY LARGE HAIL AND LOCAL DAMAGING WINDS WILL BE

PRIMARY THREAT.



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

TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

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

MOTION VECTOR 24035.





...HALES

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