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955 

WWUS20 KWNS 062028

SEL0

SPC WW 062028

MTZ000-NDZ000-SDZ000-WYZ000-070300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 580

NWS STORM PREDICTION CENTER NORMAN OK

230 PM MDT FRI AUG 6 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF SOUTHEAST MONTANA

       SMALL PART OF SOUTHWEST NORTH DAKOTA

       PARTS OF WESTERN SOUTH DAKOTA

       PARTS OF NORTHEAST WYOMING



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 230 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 70 MILES SOUTHEAST OF

GILLETTE WYOMING TO 20 MILES NORTH NORTHWEST OF BAKER MONTANA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU0).



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 579...



DISCUSSION...THUNDERSTORMS DEVELOPING ACROSS NERN WY AHEAD OF VORT

MAX NOTED MOVING NE VICINITY BIG HORN MTNS.  WITH SELY FLOW OF MDTLY

UNSTABLE AIR MASS THRU WATCH INTO SERN MT...THUNDERSTORMS EXPECTED

TO INCREASE IN INTENSITY AS THEY MOVE/DEVELOP NEWD ACROSS THE WATCH

AREA.  SUFFICIENT VEERING SHEAR PROFILES GIVEN MLCAPES TO 1500 J/KG

FOR SUPERCELL DEVELOPMENT.  THIS WOULD INCREASE THE POTENTIAL FOR

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 550. MEAN STORM

MOTION VECTOR 22020.





...HALES

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