

000 

WWUS20 KWNS 120436

SEL3

SPC WW 120436

MTZ000-NDZ000-121200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 383

NWS STORM PREDICTION CENTER NORMAN OK

1035 PM MDT MON JUN 11 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       FAR EASTERN MONTANA

       WESTERN NORTH DAKOTA



EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 1035 PM

UNTIL 600 AM MDT.



HAIL TO 1.5 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 55

STATUTE MILES EAST AND WEST OF A LINE FROM 65 MILES NORTHEAST OF

WILLISTON NORTH DAKOTA TO 40 MILES SOUTHEAST OF BAKER MONTANA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU3).



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 ARE FORMING ATOP SHALLOW COOL DOME IN WAKE OF

EWD-MOVING WIND SHIFT LINE NOW IN WRN ND.  THIS ACTIVITY APPEARS TO

BE SUPPORTED BY DEVELOPING JET ENTRANCE CIRCULATION ASSOCIATED WITH

UPR IMPULSE NOW LIFTING NNE INTO SASKATCHEWAN/MANITOBA.  GIVEN

EXISTING THERMODYNAMIC ENVIRONMENT AND LIKELIHOOD FOR THE PRESENCE

OF SUSTAINED UPDRAFTS IF UVV FIELD REMAINS IN PLACE...A THE THREAT

WILL EXIST FOR DAMAGING WIND AND HAIL.  THIS THREAT WILL BECOME MORE

WIDESPREAD IF STORMS GROW UPSCALE INTO AN MCS WITH EMBEDDED BOWING

SEGMENTS.  MODERATE UNIDIRECTIONAL  SSW MID/UPR LEVEL FLOW COULD

SUPPORT SUCH A SCENARIO...BUT ACTUAL EVOLUTION WILL NECESSARILY

DEPEND ON STORM-SCALE INTERACTIONS THAT CANNOT BE ANTICIPATED AT

THIS POINT.



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

TO 1.5 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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