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WWUS20 KWNS 262159

SEL9

SPC WW 262159

IAZ000-NEZ000-270500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 559

NWS STORM PREDICTION CENTER NORMAN OK

500 PM CDT SUN JUN 26 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTH CENTRAL AND SOUTHWEST IOWA

       EAST CENTRAL AND NORTHEAST NEBRASKA



EFFECTIVE THIS SUNDAY AFTERNOON FROM 500 PM UNTIL MIDNIGHT CDT.



HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 50

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

GRAND ISLAND NEBRASKA TO 15 MILES NORTH NORTHEAST OF OTTUMWA

IOWA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED

WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).



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 555...WW 556...WW

557...WW 558...



DISCUSSION...MULTIPLE CLUSTERS OF SEVERE STORMS IN NEB/IA WILL

CONTINUE TO MOVE EWD/ESEWD TO THE IMMEDIATE N OF THE SURFACE WARM

FRONT.  A FEED OF STRONG INSTABILITY FROM THE S /MUCAPE 3000-4000 J

PER KG/ JUST ABOVE THE BOUNDARY...AND EFFECTIVE BULK SHEAR NEAR 50

KT...WILL SUPPORT BOTH SUPERCELLS AND BOWING CLUSTERS.  VERY LARGE

HAIL AND DAMAGING WINDS WILL BE THE MAIN RISKS.  THE SRN FRINGE OF

THE WATCH AND AREAS TO THE IMMEDIATE S IN NEB/MO WILL BE MONITORED

CLOSELY FOR STORM DEVELOPMENT ALONG THE SURFACE WARM FRONT...WHERE

THE RISK FOR TORNADOES WILL BE ENHANCED.



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

TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 650. MEAN STORM

MOTION VECTOR 28025.





...THOMPSON

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