Severe storms possible Wednesday night!

Wednesday 6:00pm

MESOSCALE DISCUSSION 1208
NWS STORM PREDICTION CENTER NORMAN OK
0551 PM CDT WED JUN 04 2008

AREAS AFFECTED...FAR ERN IA...NRN IL AND NRN IND

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 042251Z - 050015Z

A SEVERE THREAT MAY DEVELOP ACROSS FAR ERN IA...NRN IL AND NRN IND
OVER THE NEXT FEW HOURS. A TORNADO ALONG WITH A THREAT FOR LARGE
HAIL AND WIND DAMAGE WILL BE POSSIBLE AS STORMS INCREASE IN
COVERAGE. A WW MAY BECOME NECESSARY THIS EVENING

LATEST SFC ANALYSIS SHOWS A WARM FRONT EXTENDING EAST TO WEST FROM
ERN IA ACROSS NRN IL AND NRN IND WITH DEWPOINTS IN THE LOWER 70S F
SOUTH OF THE BOUNDARY. RUC OBJECTIVE ANALYSIS INDICATES THE CAPPING
INVERSION HAS WEAKENED OVER THE LAST HOUR AND THIS MAY ALLOW
SCATTERED THUNDERSTORMS TO INITIATE AND MOVE NNEWD ACROSS THE MCD
AREA EARLY THIS EVENING. STRONG VERTICAL SHEAR PROFILES EVIDENT ON
REGIONAL WSR-88D VWPS AND THE AMOUNT OF INSTABILITY SUGGEST
SUPERCELLS WITH LARGE HAIL WILL BE POSSIBLE. IN ADDITION...VEERED
LOW-LEVEL FLOW WITH UNIDIRECTIONAL WINDS BELOW 6 KM MAY ALSO PROMOTE
LINEAR DEVELOPMENT WITH WIND DAMAGE POTENTIAL. ALTHOUGH THESE SHOULD
BE THE PRIMARY THREATS...LOW-LEVEL SHEAR IS STRONG ENOUGH FOR AN
ISOLATED TORNADO THREAT AS WELL.

The atmosphere will remain stable during the overnight as a stationary front remains over Central Illinois. During the day on Wednesday, the front will begin its trek to the north. During the late afternoon hours thunderstorms are expected to develop...and may turn severe. There are more indications by our computer models that tornadoes may be possible for Northern Illinois. Please be alert and aware of the weather tomorrow and know what to do if severe weather watches and warnings are issued.

Here is the NAM model's depiction of instability for tonight vs. tomorrow night. It appears that the warm front might either get caught up by the cool waters of Lake Michigan or a lake front may set up. Either way it points toward an active day for the stateline area.