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000 

WWUS20 KWNS 151941

SEL0

SPC WW 151941

NEZ000-160300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 520

NWS STORM PREDICTION CENTER NORMAN OK

240 PM CDT SUN JUL 15 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL NEBRASKA



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 240 PM UNTIL

1000 PM CDT.



HAIL TO 2.5 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 95

STATUTE MILES EAST AND WEST OF A LINE FROM 20 MILES NORTHWEST OF

AINSWORTH NEBRASKA TO 50 MILES SOUTH SOUTHWEST OF KEARNEY

NEBRASKA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0).



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 518...WW 519...



DISCUSSION...STORMS ARE BEGINNING TO DEVELOP OVER NORTH CENTRAL NEB

IN RESPONSE TO STRONG HEATING AND WEAK SYNOPTIC SCALE ASCENT IN

ADVANCE OF VORTICITY MAX MOVING SEWD ACROSS SWRN SD.  18Z LBF

SOUNDING EXHIBITED VERY STEEP LAPSE BELOW 600 MB AND DRY SUBCLOUD

LAYER...SUPPORTIVE OF STRONG WIND GUSTS AND LARGE HAIL.  FARTHER

EAST...HIGHER MOISTURE CONTENT IS CONTRIBUTING TO MLCAPE OF

2000-2500 J/KG.  WINDS VEER STRONGLY WITH HEIGHT WITH 30 KT NWLY

FLOW IN THE MID LEVELS RESULTING IN SUFFICIENT SHEAR TO ENHANCE

STORM ORGANIZATION.  ACTIVITY SHOULD SPREAD SWD/SSEWD INTO THE

EVENING HOURS.



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

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 31020.





...WEISS

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