

000 

WWUS20 KWNS 262043

SEL4

SPC WW 262043

MTZ000-270400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 754

NWS STORM PREDICTION CENTER NORMAN OK

235 PM MDT SAT JUL 26 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTH CENTRAL AND NORTHEAST MONTANA



EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 235 PM UNTIL

1000 PM MDT.



HAIL TO 3 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 65 MILES EAST

NORTHEAST OF HAVRE MONTANA TO 90 MILES EAST SOUTHEAST OF

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

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).



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 753...



DISCUSSION...SEVERE STORMS ARE NOW DEVELOPING SWD ALONG AN OUTFLOW

BOUNDARY OVER NORTH CENTRAL MT EXTENDING ACROSS SRN HILL AND NRN

CHOUTEAU CNTYS BORDER...WHILE NEW STORMS ARE DEVELOPING OVER HIGHER

TERRAIN NEAR LWT.  AIR MASS IS MOIST WITH DEW POINTS IN THE UPPER

40S TO MID 50S...AND STEEP LAPSE RATES ARE RESULTING IN MODERATE

INSTABILITY WITH MLCAPE OF 1500-2000 J/KG.  WESTERLY MID LEVEL WINDS

OF 35-45 KT AND ASSOCIATED DEEP LAYER SHEAR AOA 40 KT WILL ENHANCE

STORM ORGANIZATION AND INTENSITY.  ALTHOUGH STORMS MAY REMAIN

ISOLATED TO WIDELY SCATTERED IN COVERAGE...THERE IS POTENTIAL FOR A

FEW LONG-LIVED SUPERCELLS TO DEVELOP THIS AFTERNOON AND EVENING WITH

THREAT FOR VERY LARGE HAIL AND DAMAGING WIND GUSTS.



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

TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

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

MOTION VECTOR 26030.





...WEISS

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