AREAS AFFECTED...PORTIONS OF NERN IL / CNTRL-NRN IND
CONCERNING...SEVERE POTENTIAL...SEVERE THUNDERSTORM WATCH LIKELY
VALID 011633Z - 011730Z
PROBABILITY OF WATCH ISSUANCE...80 PERCENT
SUMMARY...THE RISK FOR ISOLD LARGE HAIL AND SEVERE MICROBURSTS WILL
INCREASE AS STORM COVERAGE INCREASES THIS AFTERNOON. SHORT TERM
TRENDS WILL BE MONITORED.
DISCUSSION...VISIBLE SATELLITE/RADAR MOSAIC OVER THE PAST FEW HOURS
HAS SHOWN A COLLAPSING TSTM COMPLEX INVOF THE IA/IL/MO BORDER. A
GROWING AREA OF TSTMS OVER NERN IL MAY BE THE RESULT OF AN ARCING
GRAVITY WAVE INTERACTING WITH A FRONTAL ZONE DRAPED ACROSS THE
REGION. 12Z DVN/ILX RAOBS FEATURED STEEP MID LEVEL LAPSE RATES
AROUND 8 DEG C/KM. AS THE BOUNDARY LAYER CONTINUES TO HEAT AND
DESTABILIZES FURTHER...UPWARDS OF 3000-4000 J/KG MLCAPE PER NAM
FORECAST SOUNDINGS WITHIN A BELT OF MODEST WLY-NWLY FLOW...ON THE
FRINGE OF A SRN MICH MID LEVEL SPEED MAX...WILL ACT TO SUPPORT
ORGANIZED SEVERE MULTICELLS CAPABLE OF ISOLD LARGE HAIL/SEVERE WIND
GUSTS.
..SMITH/THOMPSON.. 07/01/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...ILN...IWX...IND...LOT...ILX...DVN...
LAT...LON 39568647 41328918 41988935 42028795 40788485 40028462
39408541 39568647
