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WWUS20 KWNS 022232

SEL4

SPC WW 022232

NEZ000-SDZ000-030500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 474

NWS STORM PREDICTION CENTER NORMAN OK

435 PM MDT MON JUL 2 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NEBRASKA PANHANDLE

       FAR WESTERN SOUTH DAKOTA



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 435 PM UNTIL

1100 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 50

STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES NORTHEAST OF

BUFFALO SOUTH DAKOTA TO 15 MILES SOUTHWEST OF SIDNEY NEBRASKA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU4).



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 472...WW 473...



DISCUSSION...STRONG HEATING AND SURFACE CONVERGENCE ERODED CAPPING

WITH A MODERATELY UNSTABLE AIR MASS OVER THE REGION LATE THIS

AFTERNOON.  EFFECTIVE SHEAR OF 40-50 KT WILL BE MORE THAN FAVORABLE

FOR SUPERCELLS...AND WILL ENHANCE THE POTENTIAL FOR LARGE HAIL AND

DAMAGING WINDS AS ISOLATED CELLS SHIFT ESEWD THROUGH THE EVENING.



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 29015.





...EVANS

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