

458 

WWUS20 KWNS 081826

SEL0

SPC WW 081826

ILZ000-WIZ000-LMZ000-090000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 350

NWS STORM PREDICTION CENTER NORMAN OK

125 PM CDT MON JUN 8 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHEAST ILLINOIS

       SOUTHEAST WISCONSIN

       LAKE MICHIGAN



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 125 PM UNTIL 700

PM 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 55

STATUTE MILES EAST AND WEST OF A LINE FROM 20 MILES NORTH OF

MILWAUKEE WISCONSIN TO 10 MILES SOUTH OF MARSEILLES ILLINOIS.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU0).



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...SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP IN

ADVANCE OF A MID LEVEL TROUGH MOVING ENEWD FROM IA...ALONG AND S OF

THE WARM FRONT FROM SRN WI INTO NRN IL...AND IN ADVANCE OF A

PRE-FRONTAL TROUGH AND THE SURFACE LOW MOVING EWD FROM IA INTO SW

WI/NW IL.  MODERATE INSTABILITY IS EXPECTED IN THE WARM SECTOR TO

THE N OF THE DEBRIS CLOUDINESS OVER CENTRAL IL...AND PRIMARILY

UNIDIRECTIONAL DEEP LAYER WIND PROFILES WILL FAVOR SHORT LINE

SEGMENTS AND SUPERCELLS CAPABLE OF PRODUCING DAMAGING WINDS AND

LARGE HAIL.  AN ISOLATED TORNADO CANNOT BE RULED OUT /ESPECIALLY

WITH STORMS INTERACTING WITH THE WARM FRONT/...BUT GENERALLY VEERED

LOW-LEVEL WINDS IN THE WARM SECTOR AND MINIMAL INSTABILITY N OF THE

WARM FRONT WILL LIMIT THIS OVERALL THREAT.



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 27040.





...THOMPSON

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