

000 

WWUS20 KWNS 201912

SEL8

SPC WW 201912

MIZ000-WIZ000-LMZ000-LSZ000-210100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 428

NWS STORM PREDICTION CENTER NORMAN OK

210 PM CDT WED JUN 20 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       UPPER MICHIGAN

       NORTHERN AND CENTRAL WISCONSIN

       LAKE MICHIGAN

       LAKE SUPERIOR



EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 210 PM UNTIL

800 PM 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 80

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 45 MILES NORTHWEST

OF EAU CLAIRE WISCONSIN TO 30 MILES SOUTHEAST OF ESCANABA

MICHIGAN.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).



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...CONVERGENCE ALONG SEWD MOVING SURFACE TROUGH HAS AIDED

IN WEAKENING THE CAPPING INVERSION. AS RICHER BOUNDARY LAYER

MOISTURE ADVECTS INTO THE AREA FROM THE WEST...THUNDERSTORMS ARE

EXPECTED TO INCREASE IN NUMBER AND INTENSIFY. STRONG DEEP LAYER

SHEAR WILL BE FAVORABLE FOR SOME ROTATING STORMS...WITH HAIL THE

MAIN THREAT.



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 29035.





...IMY

