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453 

WWUS20 KWNS 072357

SEL1

SPC WW 072357

IAZ000-080600-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 561

NWS STORM PREDICTION CENTER NORMAN OK

655 PM CDT TUE JUL 7 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PORTIONS OF NORTHERN AND CENTRAL IOWA



EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 655 PM

UNTIL 100 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 40

STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES NORTHWEST OF

MASON CITY IOWA TO 70 MILES SOUTH OF FORT DODGE 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 560...



DISCUSSION...BOW ECHO IN SWRN MN IS EXPECTED TO TRACK SEWD/SSEWD

ALONG INSTABILITY AXIS/STATIONARY FRONT INTO NRN/CENTRAL IA DURING

THE EVENING HOURS. MODERATE INSTABILITY AND DEEP LAYER SHEAR AROUND

30 KT SHEAR WILL SUPPORT PRIMARILY A WIND THREAT WITH THIS SYSTEM.

HOWEVER...STRENGTHENING WINDS ALOFT AND UPPER IMPULSE MOVING SEWD

INTO THE REGION MAY ALSO GENERATE OTHER STORMS WITH A POTENTIAL FOR

SEVERE HAIL.



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 500. MEAN STORM

MOTION VECTOR 32030.





...IMY

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