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932 

WWUS20 KWNS 220257

SEL5

SPC WW 220257

MTZ000-NDZ000-SDZ000-221000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 375

NWS STORM PREDICTION CENTER NORMAN OK

850 PM MDT MON JUN 21 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EASTERN MONTANA

       WESTERN AND CENTRAL NORTH DAKOTA

       WESTERN AND CENTRAL SOUTH DAKOTA



EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 850 PM UNTIL

400 AM 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 105

STATUTE MILES EITHER SIDE OF A LINE FROM 40 MILES SOUTH SOUTHWEST

OF GLENDIVE MONTANA TO 85 MILES EAST SOUTHEAST OF LEMMON SOUTH

DAKOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED

WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).



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...THIS SEVERE THUNDERSTORM WATCH REPLACES

TORNADO WATCH NUMBER 367...TORNADO WATCH NUMBER 370. WATCH NUMBER

367 370 WILL NOT BE IN EFFECT AFTER 850 PM MDT. CONTINUE...WW

371...WW 372...WW 373...WW 374...



DISCUSSION...EVOLUTION OF A MESOSCALE CONVECTIVE SYSTEM CONTINUES IN

THE PRESENCE OF STRENGTHENING LOW-LEVEL WARM ADVECTION BENEATH A

DIVERGENT UPPER FLOW FIELD ACROSS THE NORTHERN HIGH PLAINS.

ACTIVITY WILL DEVELOP EASTWARD/SOUTHEASTWARD THROUGH THE WESTERN AND

CENTRAL DAKOTAS LATE THIS EVENING INTO THE OVERNIGHT HOURS...

ACCOMPANIED BY THE RISK FOR DAMAGING SURFACE WIND GUSTS AND HAIL.



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 24035.





...KERR

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