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485 

WWUS20 KWNS 300326

SEL5

SPC WW 300326

IAZ000-ILZ000-WIZ000-301000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 145

NWS STORM PREDICTION CENTER NORMAN OK

1025 PM CDT MON APR 29 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  CENTRAL AND EASTERN IOWA

  NORTHWEST ILLINOIS

  SOUTHWEST WISCONSIN



* EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 1025 PM

  UNTIL 500 AM CDT.



* PRIMARY THREATS INCLUDE...

  A FEW VERY LARGE HAIL EVENTS TO 2.5 INCHES IN DIAMETER POSSIBLE

  A FEW DAMAGING WIND GUSTS TO 70 MPH POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 60 MILES WEST OF DES

MOINES IOWA TO 30 MILES NORTHEAST OF DUBUQUE IOWA.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU5).



PRECAUTIONARY/PREPAREDNESS ACTIONS...



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.



&&



DISCUSSION...THUNDERSTORMS ARE NOW INCREASING IN NUMBER ACROSS

CENTRAL IOWA IN THE PRESENCE OF LARGE SCALE ASCENT ASSOCIATED WITH

LOW-LEVEL WARM ADVECTION...WHICH LIKELY WILL STRENGTHEN ON THE NOSE

OF AN INTENSIFYING 850 MB JET INTO THE OVERNIGHT HOURS.  DESPITE

SOMEWHAT MARGINAL MOISTURE...INSTABILITY ASSOCIATED WITH VERY STEEP

LAPSE RATES WILL CONTINUE TO SUPPORT THE RISK FOR LARGE HAIL IN

STRONGEST STORMS.  ACTIVITY MAY GRADUALLY CONSOLIDATE INTO A SMALL

STORM CLUSTER...WITH SOME INCREASE IN POTENTIAL FOR DAMAGING WINDS

WHILE SPREADING NORTHEASTWARD TOWARD SOUTHWESTERN WISCONSIN AND

NORTHWESTERN ILLINOIS.



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

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 24035.





...KERR

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