

397 

WWUS20 KWNS 200842

SEL1

SPC WW 200842

IAZ000-NEZ000-201500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 521

NWS STORM PREDICTION CENTER NORMAN OK

345 AM CDT MON JUN 20 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND WESTERN IOWA

       EASTERN NEBRASKA



EFFECTIVE THIS MONDAY MORNING FROM 345 AM UNTIL 1000 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 40

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 5 MILES SOUTH

SOUTHWEST OF COLUMBUS NEBRASKA TO 30 MILES SOUTH OF WATERLOO

IOWA.  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 518...WW 519...



DISCUSSION...SCATTERED STRONG TO SEVERE THUNDERSTORMS PERSIST OVER

EASTERN NEB AND WESTERN IA.  THESE STORMS WILL CONTINUE TO TRACK

EASTWARD ALONG BAROCLINIC ZONE...WITH AMPLE MOISTURE/INSTABILITY

BEING FED FROM THE SOUTH.  LARGE HAIL APPEARS TO BE THE MAIN THREAT

WITH THESE STORMS.



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 27035.





...HART

