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104 

WWUS20 KWNS 111904

SEL3

SPC WW 111904

MTZ000-SDZ000-WYZ000-120200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 453

NWS STORM PREDICTION CENTER NORMAN OK

105 PM MDT SUN JUL 11 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       FAR SOUTHEAST MONTANA

       WESTERN SOUTH DAKOTA

       NORTHEAST WYOMING



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 105 PM UNTIL 800

PM MDT.



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 80

STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES NORTH

NORTHEAST OF BROADUS MONTANA TO 80 MILES SOUTH SOUTHEAST OF RAPID

CITY SOUTH DAKOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).



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 450...WW 451...WW 452...



DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND

INTENSITY THIS AFTERNOON IN ADVANCE OF MIDLEVEL TROUGH PROGRESSING

ESEWD THROUGH THE NRN HIGH PLAINS.  RESIDUAL BOUNDARY LAYER

DEWPOINTS IN THE 50S WITHIN POST-FRONTAL AIR MASS COUPLED WITH STEEP

LAPSE RATES WILL SERVE TO BOOST MLCAPE TO 1000-2000 J/KG THROUGH THE

REMAINDER OF THE AFTERNOON.  WHILE NOT OVERLY STRONG...THE PRESENCE

OF 30-40 KT DEEP-LAYER SHEAR IN CONCERT WITH THE STEEP LAPSE RATES

AND CONVECTIVE INSTABILITY WILL SUPPORT THE DEVELOPMENT OF ORGANIZED

STORMS INCLUDING SUPERCELLS WITH THE THREAT FOR LARGE HAIL AND

DAMAGING WINDS.



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 29025.





...MEAD

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