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WWUS20 KWNS 010110

SEL9

SPC WW 010110

ILZ000-INZ000-LMZ000-010500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 579

NWS STORM PREDICTION CENTER NORMAN OK

815 PM CDT THU JUN 30 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF NORTHEAST ILLINOIS

       PARTS OF NORTHWEST INDIANA

       LAKE MICHIGAN



EFFECTIVE THIS THURSDAY NIGHT FROM 815 PM UNTIL MIDNIGHT CDT.



HAIL TO 2.5 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 35

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

MEIGS FIELD ILLINOIS TO 70 MILES SOUTH SOUTHWEST OF VALPARAISO

INDIANA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).



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 577...WW 578...



DISCUSSION...SUPERCELLS OVER SRN LM WILL CONTINUE TO DEVELOP SWD

ACROSS CHICAGO METRO AREA.  STRONG DEEP LAYER SHEAR AND MLCAPES AOA

2500 J/KG WILL CONTINUE TO SUPPORT POTENTIAL FOR NOT ONLY VERY LARGE

HAIL BUT DAMAGING WINDS AS STORMS MOVE INLAND.



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 550. MEAN STORM

MOTION VECTOR 36020.





...HALES

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