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WWUS20 KWNS 292030

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URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 549

NWS STORM PREDICTION CENTER NORMAN OK

330 PM CDT THU JUL 29 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       PARTS OF NORTHCENTRAL NEBRASKA

       PARTS OF SOUTHERN AND WESTERN SOUTH DAKOTA



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 330 PM UNTIL

1000 PM CDT.



TORNADOES...HAIL TO 3.5 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 90 STATUTE

MILES EAST AND WEST OF A LINE FROM 35 MILES EAST NORTHEAST OF

RAPID CITY SOUTH DAKOTA TO 40 MILES EAST OF MULLEN NEBRASKA.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU9).



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 548...



DISCUSSION...AIR MASS NOW QUITE UNSTABLE ACROSS THE WATCH AREA AND

FAVORABLY SHEARED TO SUPPORT SUPERCELLS.  A SUPERCELL HAS DEVELOPED

S END OF BLACK HILLS AND WILL LIKELY CONTINUE SEWD INTO A FAVORABLE

ENVIRONMENT FOR NOT ONLY LARGE HAIL BUT POSSIBLY TORNADIC

DEVELOPMENT.  ADDITIONAL SEVERE STORMS ARE LIKELY SEWD INTO NCENTRAL

NEB WHERE SIMILAR CONDITIONS PREVAIL.



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

SURFACE AND ALOFT TO 3.5 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

550. MEAN STORM MOTION VECTOR 30015.





...HALES

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