

312 

WWUS20 KWNS 152122

SEL8

SPC WW 152122

MTZ000-160300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 648

NWS STORM PREDICTION CENTER NORMAN OK

325 PM MDT FRI JUL 15 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHEAST MONTANA



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 325 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 60

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

BILLINGS MONTANA TO 40 MILES NORTH NORTHEAST 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.



DISCUSSION...SCATTERED THUNDERSTORMS ARE EXPECTED TO INTENSIFY OVER

THE HIGHER TERRAIN OF SOUTH-CENTRAL MT THIS AFTERNOON AND SPREAD

EASTWARD ACROSS THE WATCH AREA.  DEWPOINTS IN THE 50S AND MUCAPE

VALUES OF 1500-2000 J/KG...COUPLED WITH SUFFICIENT WESTERLY FLOW

ALOFT...WILL POSE A RISK OF ISOLATED SUPERCELLS CAPABLE OF LARGE

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 500. MEAN STORM

MOTION VECTOR 26030.





...HART

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