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000 

WWUS20 KWNS 172223

SEL3

SPC WW 172223

MTZ000-SDZ000-WYZ000-180600-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 613

NWS STORM PREDICTION CENTER NORMAN OK

520 PM CDT FRI AUG 17 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       FAR SOUTHEAST MONTANA

       WESTERN AND SOUTH CENTRAL SOUTH DAKOTA

       NORTHEAST WYOMING



EFFECTIVE THIS FRIDAY AFTERNOON AND SATURDAY MORNING FROM 520 PM

UNTIL 100 AM CDT.



TORNADOES...HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 105 STATUTE

MILES EAST AND WEST OF A LINE FROM 105 MILES NORTH OF RAPID CITY

SOUTH DAKOTA TO 75 MILES SOUTH SOUTHWEST OF PHILIP SOUTH DAKOTA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU3).



REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND 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.



OTHER WATCH INFORMATION...CONTINUE...WW 612...



DISCUSSION...TSTMS/SUPERCELLS EXPECTED TO POSE A THREAT FOR LARGE

HAIL/HIGH WIND AND POSSIBLE TORNADOES IN WRN SD AND POSSIBLY

ADJACENT AREAS OF WY FAR SE MT THIS EVENING AS HEATING AND LOW LVL

MOISTURE INFLOW CONTINUE AHEAD OF APPROACHING UPR IMPULSE.  MODERATE

ESELY LOW LVL FLOW /INVOF WEAK FRONT EXTENDING SE ALONG THE MID MO

VLY/ BENEATH 25-30 KT WSWLY 500 MB WINDS SUGGESTS POTENTIAL FOR A

FEW SUSTAINED SUPERCELLS WITH LOW LVL ROTATION.



AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL

SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

550. MEAN STORM MOTION VECTOR 28015.





...CORFIDI

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