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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 231

NWS STORM PREDICTION CENTER NORMAN OK

945 PM MDT FRI MAY 28 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EASTERN MONTANA

       WESTERN NORTH DAKOTA



EFFECTIVE THIS FRIDAY NIGHT AND SATURDAY MORNING FROM 945 PM

UNTIL 500 AM MDT.



HAIL TO 2.5 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 70

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

BROADUS MONTANA TO 65 MILES NORTH NORTHEAST OF WOLF POINT

MONTANA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).



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.



DISCUSSION...TSTMS HAVE BEGUN TO FORM OVER SE MT...NW OF SSW/NNE

STNRY FRONT EXTENDING FROM NE WY INTO N CNTRL ND.  THESE STORMS

SHOULD INCREASE IN COVERAGE/STRENGTH...AND MOVE/DEVELOP NNE ACROSS

THE REMAINDER OF ERN MT AND POSSIBLY WRN ND THROUGH EARLY SAT AS NRN

RCKYS UPR LOW EDGES SLOWLY EWD...AND ASSOCIATED SHORTWAVE IMPULSE

CONTINUES MORE RAPIDLY NNE FROM ERN ID/WRN WY.

AREA VWP DATA AND MODEL FCSTS SUGGEST THAT AMPLE CLOUD LAYER SHEAR

WILL EXIST FOR ELEVATED SUSTAINED STORMS/SUPERCELLS.  COUPLED WITH

DEEP EML AND SUBSTANTIAL MOISTURE AVAILABILITY ON NW EDGE OF SLY

LLJ...SETUP WILL BE FAVORABLE FOR UPSCALE DEVELOPMENT INTO ONE OR

MORE STORM CLUSTERS WITH LARGE HAIL AND POSSIBLY DMGG WIND.



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

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

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

MOTION VECTOR 21035.





...CORFIDI

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