AREAS AFFECTED...ERN IL...MUCH OF INDIANA...SWRN LOWER MI
CONCERNING...SEVERE POTENTIAL...WATCH LIKELY
VALID 181225Z - 181400Z
PROBABILITY OF WATCH ISSUANCE...80 PERCENT
SUMMARY...LINE OF THUNDERSTORMS WILL ADVANCE EWD ACROSS ERN IL INTO
INDIANA AND SWRN LOWER MI THIS MORNING...WITH SVR THREAT EXPECTED TO
INCREASE WITH TIME. ALTHOUGH A WW IS NOT IMMEDIATELY NECESSARY...ONE
WILL LIKELY BE ISSUED LATER THIS MORNING.
DISCUSSION...SURFACE LOW PRESSURE CONTINUES TO ADVANCE NEWD ACROSS
THE MID MS VALLEY THIS MORNING AHEAD OF A SHORTWAVE TROUGH EJECTING
OVER THE CNTRL PLAINS. LINE OF THUNDERSTORMS OCCURRING AHEAD OF THE
SURFACE LOW IS CURRENTLY MOVING EWD ACROSS CNTRL IL WITHIN A WEAKLY
UNSTABLE AIRMASS. HOWEVER...LATEST SURFACE OBSERVATIONS AND
OBJECTIVE ANALYSIS GUIDANCE INDICATE INCREASING THETA-E VALUES AHEAD
OF THE LINE OVER ERN IL AND WRN INDIANA. IN ADDITION...EARLY VISIBLE
SATELLITE IMAGERY SHOWS MAINLY CLEAR SKIES ACROSS INDIANA...WHICH
WILL FURTHER AID IN BOUNDARY LAYER DESTABILIZATION WITH CONTINUED
DAYTIME HEATING. GIVEN THE PRESENCE OF 60+ KT OF DEEP-LAYER SWLY
FLOW OVERSPREADING THE AREA...THE THREAT FOR DAMAGING WIND GUSTS AND
A COUPLE OF TORNADOES IS EXPECTED TO INCREASE THIS MORNING.
..GARNER/HART.. 04/18/2013
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...IWX...GRR...IND...PAH...LOT...ILX...LSX...
LAT...LON 39828903 41828776 42388506 40108523 38528691 38408927
39828903
