WATCHES: Severe Thunderstorm Watch Number 300

WWUS20 KWNS 122107
SEL0
SPC WW 122107
ILZ000-INZ000-MIZ000-OHZ000-WIZ000-LEZ000-LMZ000-130600-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 300
NWS STORM PREDICTION CENTER NORMAN OK
400 PM CDT WED JUN 12 2013

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
NORTHEAST ILLINOIS
NORTHERN INDIANA
SOUTHERN LOWER MICHIGAN
NORTHWEST OHIO
SOUTHEAST WISCONSIN
LAKE ERIE
LAKE MICHIGAN

* EFFECTIVE THIS WEDNESDAY AFTERNOON AND THURSDAY MORNING FROM
400 PM UNTIL 100 AM CDT.

...THIS IS A PARTICULARLY DANGEROUS SITUATION...

* PRIMARY THREATS INCLUDE...
NUMEROUS SIGNIFICANT DAMAGING WIND GUSTS TO 80 MPH LIKELY
SEVERAL VERY LARGE HAIL EVENTS TO 2 INCHES IN DIAMETER POSSIBLE
A FEW TORNADOES POSSIBLE

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70
STATUTE MILES EITHER SIDE OF A LINE FROM 40 MILES EAST OF FINDLAY
OHIO TO 60 MILES SOUTH SOUTHWEST OF RACINE WISCONSIN. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU0).

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 298...WW 299...

DISCUSSION...THUNDERSTORMS ARE EXPECTED TO CONSOLIDATE INTO A
FORWARD PROPAGATING CONVECTIVE SYSTEM OVER THE NEXT SEVERAL HOURS AS
A COMPACT BUT PROGRESSIVE SHORTWAVE TROUGH ACTS ON A VERY UNSTABLE
AIRMASS ACROSS THE UPPER MIDWEST/LOWER GREAT LAKES REGION. ONGOING
CONVECTION NEAR A SURFACE LOW AND WARM FRONT...FROM IOWA EAST ACROSS
NORTHERN ILLINOIS...EXISTS WHERE LOW LEVEL SHEAR AND ASCENT WILL
CONTRIBUTE TO A FEW MORE HOURS OF TORNADO POTENTIAL IN WATCH 298.
EVENTUALLY STORMS WILL CONGEAL INTO A LARGE MASS OF CONVECTION WITH
ASCENT AND STRENGTHENING SHEAR SUPPORTING A POSSIBLE DERECHO OR
WIDESPREAD DAMAGING WIND EVENT. THIS TRANSITION IS LIKELY TO OCCUR
ACROSS THE CHICAGO AREA AND SRN LAKE MICHIGAN INTO EARLY EVENING.
PRIOR TO THIS EVOLUTION THE LARGE HAIL AND TORNADO POSSIBILITIES
WILL BE GREATEST WITHIN THE WESTERN PORTIONS OF WATCH 300. WITH
TIME...MORE WIDESPREAD DAMAGING WIND POTENTIAL WILL DEVELOP AS THE
MCS RACES EAST ACROSS SOUTHERN MI/NORTHERN IND...AND INTO NORTHWEST
OH THROUGH LATE TONIGHT.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM
MOTION VECTOR 28045.


...CARBIN

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