

182 

WWUS20 KWNS 142209

SEL2

SPC WW 142209

MTZ000-NDZ000-SDZ000-WYZ000-150600-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 412

NWS STORM PREDICTION CENTER NORMAN OK

410 PM MDT SUN JUN 14 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHEAST MONTANA

       FAR SOUTHWEST NORTH DAKOTA

       WESTERN AND CENTRAL SOUTH DAKOTA

       NORTHEAST WYOMING



EFFECTIVE THIS SUNDAY AFTERNOON FROM 410 PM UNTIL MIDNIGHT 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 95

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 30 MILES SOUTHWEST

OF BROADUS MONTANA TO 30 MILES EAST SOUTHEAST OF PIERRE 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 407...WW 408...WW

409...WW 410...WW 411...



DISCUSSION...TSTMS/SUPERCELLS EXPECTED TO INCREASE IN

COVERAGE/STRENGTH ALONG AND S OF WEAK W-E FRONT OVER WRN SD...AND

ALONG LEE TROUGH EXTENDING S ALONG THE WY/SD BORDER.  OTHER STORMS

MAY FOCUS INVOF VORT CENTER MOVING SLOWLY NWD ACROSS SE MT.  SVR

HAIL/WIND AND POSSIBLY A TORNADO WILL BE POSSIBLE WITH THE

STORMS...PARTICULARLY IN SD.  SRN PARTS OF WW MAY REQUIRE UPGRADE TO

TORNADO LATER THIS EVE IF 700 MB FLOW STRENGTHENS BEYOND WHAT IS NOW

EXPECTED...AND STORM MODE REMAINS DISCRETE.



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 26020.





...CORFIDI

