

146 

WWUS20 KWNS 241434

SEL1

SPC WW 241434

MTZ000-NDZ000-242100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 421

NWS STORM PREDICTION CENTER NORMAN OK

835 AM MDT SUN JUN 24 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHEAST MONTANA

       WESTERN AND CENTRAL NORTH DAKOTA



EFFECTIVE THIS SUNDAY MORNING AND AFTERNOON FROM 835 AM UNTIL 300

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 50

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 25 MILES NORTH

NORTHWEST OF WOLF POINT MONTANA TO 15 MILES EAST NORTHEAST OF

BISMARCK NORTH DAKOTA.  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...SEVERE STORMS CROSSING THE NERN MT/NWRN ND BORDER ARE

EXPECTED TO PROPAGATE ESEWD ALONG THE 700 MB TEMPERATURE GRADIENT ON

THE NERN EDGE OF THE EML/CAPPING INVERSION.  ADDITIONAL STRONG

CONVECTION NE OF GGW MAY ALSO INTENSIFY AND TRACK ESEWD IN THE WAKE

OF THE STORM ALONG THE BORDER.  VERY STEEP MID LEVEL LAPSE RATES AND

AMPLE ELEVATED MOISTURE IS RESULTING IN STRONG INSTABILITY BASED

ABOVE THE PBL.  STRONG EFFECTIVE BULK SHEAR WILL MAINTAIN STORM

ORGANIZATION AND INTENSITY...WITH CONTINUED POTENTIAL FOR LARGE HAIL

AND DAMAGING WIND GUSTS.



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 29030.





...WEISS

