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WWUS20 KWNS 110358

SEL1

SPC WW 110358

NEZ000-111000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 621

NWS STORM PREDICTION CENTER NORMAN OK

1055 PM CDT SUN JUL 10 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EASTERN NEBRASKA



EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 1055 PM UNTIL

500 AM CDT.



HAIL TO 1.5 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 75

STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES EAST

SOUTHEAST OF GRAND ISLAND NEBRASKA TO 35 MILES NORTHEAST OF

NORFOLK NEBRASKA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).



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 618...WW 619...WW 620...



DISCUSSION...BOWING MCS OVER CNTRL NEB IS EXPECTED TO CONTINUE

LIFTING NEWD ACROSS WATCH AREA WITH ADDITIONAL DEVELOPMENT LIKELY

ALONG THE ERN FLANK OF SYSTEM WITHIN EXIT REGION OF

STRENGTHENING...NOCTURNAL LLJ.  00Z OAX SOUNDING SHOWED THE PRESENCE

OF A VERY UNSTABLE ENVIRONMENT WITH MUCAPE UPWARDS OF 5000-7000

J/KG...WHICH WILL SERVE TO ENHANCE ROBUST UPDRAFT DEVELOPMENT ALONG

THE LEADING EDGE OF SYSTEM COLD POOL.  DAMAGING WINDS WILL BE THE

PRIMARY HAZARD...THOUGH SOME LARGE HAIL WILL ALSO BE POSSIBLE.



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

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 600. MEAN STORM

MOTION VECTOR 24035.





...MEAD

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