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000 

WWUS20 KWNS 031943

SEL8

SPC WW 031943

MTZ000-040300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 218

NWS STORM PREDICTION CENTER NORMAN OK

140 PM MDT THU MAY 3 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EASTERN MONTANA



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 140 PM UNTIL

900 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 65

STATUTE MILES EAST AND WEST OF A LINE FROM 50 MILES NORTH OF

GLASGOW MONTANA TO 55 MILES WEST SOUTHWEST OF BROADUS MONTANA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU8).



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 217...



DISCUSSION...STORMS HAVE DEVELOPED AHEAD OF MID/UPR LEVEL TROUGH

MOVING NWD FROM CENTRAL MT INTO NORTH CENTRAL/CENTRAL WY.  AIR MASS

SHOWING CONTINUED DESTABILIZATION AS MUCAPE IS 1300-1400 J/KG WITH

STEEP LOW/MID LEVEL LAPSE RATES BETWEEN 7-8C/KM.  AIR MASS EXPECTED

TO REACH TO NEAR 1800 J/KG WITH CONTINUED HEATING INCREASING THE

THREAT FOR HAIL/DAMAGING WINDS.



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 400. MEAN STORM

MOTION VECTOR 19035.





...MCCARTHY

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