

516 

WWUS20 KWNS 180357

SEL4

SPC WW 180357

COZ000-NEZ000-181000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 454

NWS STORM PREDICTION CENTER NORMAN OK

1100 PM CDT WED JUN 17 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EXTREME NORTHEAST COLORADO

       WESTERN AND NORTHERN NEBRASKA



EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 1100 PM

UNTIL 500 AM CDT.



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 70

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 30 MILES SOUTHWEST

OF ALLIANCE NEBRASKA TO 35 MILES NORTHEAST OF BROKEN BOW

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...THIS SEVERE THUNDERSTORM WATCH REPLACES

TORNADO WATCH NUMBER 445. WATCH NUMBER 445 WILL NOT BE IN EFFECT

AFTER 1100 PM CDT. CONTINUE...WW 446...WW 447...WW 448...WW

449...WW 450...WW 451...WW 452...WW 453...



DISCUSSION...THUNDERSTORMS FROM NE CO INTO THE NEB PANHANDLE MAY

CONSOLIDATE INTO A SMALL MCS AND MOVE EWD ACROSS NEB THROUGH THE

EARLY MORNING HOURS.  A CORRIDOR OF MODERATE INSTABILITY AND

EFFECTIVE BULK SHEAR OF 50-60 KT WILL SUPPORT SUPERCELLS AND

POTENTIALLY A BOWING CLUSTER CAPABLE OF PRODUCING 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 500. MEAN STORM

MOTION VECTOR 27030.





...THOMPSON

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