

668 

WWUS20 KWNS 042243

SEL4

SPC WW 042243

MTZ000-050700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 354

NWS STORM PREDICTION CENTER NORMAN OK

430 PM MDT MON JUN 4 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND SOUTHERN MONTANA



EFFECTIVE THIS MONDAY AFTERNOON AND TUESDAY MORNING FROM 430 PM

UNTIL 100 AM MDT.



HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 75

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 105

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

HAVRE MONTANA TO 25 MILES EAST SOUTHEAST OF DILLON 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 352...WW 353...



DISCUSSION...SCTD STRONG TSTMS...INCLUDING ONE OR TWO DEVELOPING

SUPERCELLS...HAVE FORMED OVER THE WRN MT MOUNTAINS IN STRENGTHENING

SSW FLOW DOWNSTREAM FROM POTENT/AMPLIFYING SHORTWAVE TROUGH OVER

CA/ORE.  COMBINATION OF INCREASING WIND FIELD/LARGE SCALE FORCING

FOR ASCENT...CONTINUED SFC HEATING...AND ESELY LOW LVL MOISTURE

INFLOW SUGGEST THAT STORMS LIKELY WILL INCREASE IN NUMBER AND

STRENGTH E OF THE MOUNTAINS.  THE ACTIVITY MAY EVOLVE INTO ONE OR

TWO SUSTAINED CLUSTERS.  EMBEDDED SUPERCELLS IN THESE SYSTEMS WILL

BE CAPABLE OF HIGH WIND AND LARGE HAIL.  WITH TIME...THE THREAT FOR

TORNADOES MAY INCREASE AS THE STORMS ENCOUNTER AN INCREASINGLY

MOIST/MORE STRONGLY SHEARED LOW LVL ENVIRONMENT.  THIS MAY REQUIRE

PARTIAL UPGRADE OF THE SVR WATCH TO A TORNADO WATCH...ESPECIALLY

ACROSS N CNTRL MT.

FARTHER SE...A SEPARATE AREA OF TSTMS IS EXPECTED TO CONTINUE

MOVING/DEVELOPING NNE FROM THE MOUNTAINS OF NRN WY/S CNTRL MT.

WHILE DEEP SHEAR WILL REMAIN WEAKER THERE RELATIVE TO POINTS FARTHER

N/W...IT WILL BE SUFFICIENT FOR SOME ORGANIZED/POSSIBLY SVR STORMS

THROUGH LATER TNGT.



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

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM

MOTION VECTOR 21035.





...CORFIDI

