

000 

WWUS20 KWNS 042106

SEL7

SPC WW 042106

MTZ000-050400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 657

NWS STORM PREDICTION CENTER NORMAN OK

305 PM MDT FRI JUL 4 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL MONTANA



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 305 PM UNTIL

1000 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 60

STATUTE MILES EAST AND WEST OF A LINE FROM 45 MILES SOUTH OF

LIVINGSTON MONTANA TO 65 MILES EAST NORTHEAST OF HAVRE 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.



OTHER WATCH INFORMATION...CONTINUE...WW 656...



DISCUSSION...THUNDERSTORMS INCREASING THIS AFTERNOON OVER HIGHER

TERRAIN OF SWRN MT...AND THIS TREND WILL CONTINUE AND SPREAD NEWD

THROUGH THE EVENING ACROSS CENTRAL MT AHEAD OF APPROACHING UPPER

TROUGH.  STRONG HEATING HAS ERODED CAP AND IS SUPPORTING MODERATE

INSTABILITY ACROSS THE REGION...WITH EFFECTIVE SHEAR INCREASING THIS

EVENING.  SUPERCELLS AND ORGANIZED LINES/BOW ECHOES MAY EVOLVE AS

ACTIVITY DEVELOPS NEWD LATE TODAY AND THIS EVENING WITH THREATS OF

HAIL AND 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 450. MEAN STORM

MOTION VECTOR 24025.





...EVANS

