

564 

WWUS20 KWNS 180607

SEL7

SPC WW 180607

IAZ000-NEZ000-181300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 487

NWS STORM PREDICTION CENTER NORMAN OK

110 AM CDT SUN JUL 18 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND WESTERN IOWA

       EAST CENTRAL NEBRASKA



EFFECTIVE THIS SUNDAY MORNING FROM 110 AM UNTIL 800 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 NORTH OF

LINCOLN NEBRASKA TO 45 MILES SOUTH SOUTHEAST OF WATERLOO IOWA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU7).



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 486...



DISCUSSION...ONE INTENSE THUNDERSTORM CLUSTER IS MOVING SSEWD ACROSS

NRN IA...WHILE ANOTHER AREA OF STORMS IS DEVELOPING ALONG AN

EWD-MOVING OUTFLOW BOUNDARY ACROSS ERN NEB.  EACH CLUSTER WILL BE

CAPABLE OF PRODUCING DAMAGING WINDS/LARGE HAIL...AND THE

CLUSTERS/OUTFLOWS ARE EXPECTED TO MERGE IN THE NEXT FEW HOURS ACROSS

WRN/CENTRAL IA AND SUPPORT CONTINUED SEVERE STORM DEVELOPMENT IN THE

CORRIDOR OF STRONG INSTABILITY.



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 600. MEAN STORM

MOTION VECTOR 31030.





...THOMPSON

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