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000 

WWUS20 KWNS 171927

SEL9

SPC WW 171927

MTZ000-NDZ000-SDZ000-WYZ000-180300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 559

NWS STORM PREDICTION CENTER NORMAN OK

130 PM MDT TUE JUN 17 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHEASTERN MONTANA

       PARTS OF SOUTHWEST NORTH DAKOTA

       WESTERN SOUTH DAKOTA

       NORTHEAST WYOMING



EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 130 PM UNTIL

900 PM MDT.



HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80

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



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 120

STATUTE MILES EAST AND WEST OF A LINE FROM 30 MILES NORTH

NORTHEAST OF MILES CITY MONTANA TO 80 MILES SOUTH SOUTHWEST OF

RAPID CITY SOUTH DAKOTA.  FOR A COMPLETE DEPICTION OF THE WATCH

SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).



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 557...WW 558...



DISCUSSION...AIR MASS HAS BECOME MDTLY UNSTABLE ACROSS WATCH AREA

WHERE SHEAR PROFILES ARE FAVORABLE FOR ORGANIZED STORM DEVELOPMENT

INCLUDING SUPERCELLS.  THUNDERSTORMS WILL INCREASE IN NUMBER AND

INTENSITY REMAINDER OF AFTERNOON...DEVELOPING SEWD IN NWLY FLOW.

VERY LARGE HAIL AND DAMAGING DOWNBURSTS WINDS WILL BE PRIMARY

THREAT...PARTICULARLY WITH ANY SUPERCELL.



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

TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 32025.





...HALES

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