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913 

WWUS20 KWNS 180314

SEL8

SPC WW 180314

IAZ000-ILZ000-INZ000-WIZ000-LMZ000-180900-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 318

NWS STORM PREDICTION CENTER NORMAN OK

1015 PM CDT TUE JUN 17 2014



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  NORTHEAST IOWA

  NORTHERN ILLINOIS

  EXTREME NORTHWEST INDIANA

  SOUTHERN WISCONSIN

  LAKE MICHIGAN



* EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 1015 PM

  UNTIL 400 AM CDT.



* PRIMARY THREATS INCLUDE...

  SCATTERED LARGE HAIL AND ISOLATED VERY LARGE HAIL EVENTS TO 2

    INCHES IN DIAMETER POSSIBLE

  SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE

  A TORNADO OR TWO POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60

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

NORTHWEST OF CEDAR RAPIDS IOWA TO 60 MILES SOUTHEAST OF RACINE

WISCONSIN.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).



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.



&&



OTHER WATCH INFORMATION...CONTINUE...WW 313...WW 314...WW

315...WW 316...WW 317...



DISCUSSION...STORMS WILL CONTINUE TO INCREASE IN COVERAGE/INTENSITY

FROM E/NE IA INTO NRN IL ALONG THE WARM FRONT DURING THE NEXT FEW

HOURS.  ADDITIONAL STORM DEVELOPMENT WILL ALSO BE POSSIBLE JUST N OF

THE BOUNDARY INTO SRN WI AS A STRENGTHENING LOW-LEVEL JET OVER IA

SUPPORTS INCREASING WARM ADVECTION.  THE COMBINATION OF STRONG

INSTABILITY AND VERTICAL SHEAR WILL BE SUFFICIENT FOR SUPERCELLS

INITIALLY...WHEN A TORNADO CANNOT BE RULED OUT.  HOWEVER...THE

PRIMARY RISKS WILL BE LARGE HAIL WITH THE INITIAL STORMS...AND

DAMAGING WINDS AS STORMS EVENTUALLY GROW UPSCALE INTO OR MORE

CLUSTERS.



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 550. MEAN STORM

MOTION VECTOR 28025.





...THOMPSON

