

676 

WWUS20 KWNS 031937

SEL7

SPC WW 031937

MTZ000-040200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 457

NWS STORM PREDICTION CENTER NORMAN OK

135 PM MDT TUE JUL 3 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHEAST MONTANA



EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 135 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 95

STATUTE MILES EAST AND WEST OF A LINE FROM 60 MILES NORTH

NORTHEAST OF GLASGOW MONTANA TO 80 MILES WEST SOUTHWEST OF

GLENDIVE MONTANA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



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...THUNDERSTORMS WILL FORM ALONG A COLD FRONT PROGRESSING

EWD FROM CENTRAL INTO ERN MT...WITH THE GREATER STORM

COVERAGE/INTENSITY EXPECTED ACROSS NE MT THIS AFTERNOON.  AN

INCREASE IN LOW-LEVEL MOISTURE FROM THE SE AND STRONG DAYTIME

HEATING...BENEATH STEEP LAPSE RATES...HAS BOOSTED MLCAPE TO AOA 2000

J/KG AND WEAKENED CONVECTIVE INHIBITION ALONG THE FRONT.  DEEP-LAYER

VERTICAL SHEAR WILL BE SUFFICIENT FOR EMBEDDED SUPERCELLS WITH THE

RISK FOR LARGE HAIL...THOUGH A PRIMARILY MODE EVOLUTION WILL SUPPORT

THE POTENTIAL FOR DAMAGING WINDS THROUGH THIS EVENING.



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 26030.





...THOMPSON

