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026 

WWUS20 KWNS 270753

SEL2

SPC WW 270753

IAZ000-MOZ000-271400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 422

NWS STORM PREDICTION CENTER NORMAN OK

255 AM CDT SUN JUN 27 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       MUCH OF CENTRAL AND SOUTHERN IOWA

       PART OF NORTHERN MISSOURI



EFFECTIVE THIS SUNDAY MORNING FROM 255 AM UNTIL 900 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 60

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 60 MILES NORTHWEST

OF LAMONI IOWA TO 40 MILES SOUTH SOUTHEAST OF CEDAR RAPIDS IOWA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU2).



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...THIS SEVERE THUNDERSTORM WATCH REPLACES

SEVERE THUNDERSTORM WATCH NUMBER 419. WATCH NUMBER 419 WILL NOT

BE IN EFFECT AFTER 255 AM CDT. CONTINUE...WW 420...WW 421...



DISCUSSION...EVOLVING TSTM COMPLEX OVER WRN IA IS MOVING THROUGH A

VERY MOIST AND MODERATELY UNSTABLE AIR MASS WHERE MLCAPE REMAINS

AROUND 2000-2500 J/KG.  MOREOVER...A 40-50 KT SWLY LLJ IS GRADUALLY

MIGRATING EWD INTO THE REGION WHICH WILL SERVE TO ENHANCE INFLOW

INTO TSTM CLUSTER.  AS SUCH...CONDITIONS APPEAR FAVORABLE FOR THE

DEVELOPMENT OF A FORWARD-PROPAGATING SYSTEM WITH THE PRIMARY HAZARD

BEING DAMAGING WIND GUSTS.



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 28035.





...MEAD

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