ZCZC SPCSWOMCD ALL
ACUS11 KWNS 211823 
SPC MCD 211823 
OHZ000-MIZ000-INZ000-ILZ000-212030-

MESOSCALE DISCUSSION 1349
NWS STORM PREDICTION CENTER NORMAN OK
0123 PM CDT THU JUL 21 2016

AREAS AFFECTED...EXTREME NERN IL...PORTIONS OF SRN LOWER MI...NRN
INDIANA...NWRN OH...ADJACENT LE

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 211823Z - 212030Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THUNDERSTORM COVERAGE IS EXPECTED TO INCREASE THIS
AFTERNOON WITH A RISK FOR ISOLATED DAMAGING WINDS AND PERHAPS LARGE
HAIL. IT REMAINS UNCLEAR WHETHER A WATCH WILL BE NEEDED...HOWEVER
THUNDERSTORM TRENDS WILL BE MONITORED.

DISCUSSION...THE LEADING EDGE OF A BROKEN LINE OF THUNDERSTORMS
CONTINUES TO MOVE SOUTHEAST AT 35 MPH ACROSS SOUTHWEST LOWER
MI/NORTHWEST INDIANA WITH SEVERAL CELLS DEVELOPING AHEAD OF THE LINE
IN THE VICINITY. DOWNSTREAM...STRONG HEATING OF UPPER 60S/LOWER 70S
SURFACE DEW POINTS HAS YIELDED MODERATE-STRONG SURFACE-BASED
INSTABILITY. ENVIRONMENTAL WIND FIELDS WITHIN THE DISCUSSION AREA
REMAIN MODEST AT BEST...AND THE LATEST KIWX VWP INDICATES AROUND 20
KTS OF DEEP-LAYER SHEAR. 

A PRONOUNCED COLD POOL ASSOCIATED WITH THE LONG-LIVED MCS CONTINUES
TO MOVE SOUTHEAST AND IS EXPECTED TO RESULT IN AN INCREASE IN
THUNDERSTORM COVERAGE DURING THE NEXT FEW HOURS AS IT ENCOUNTERS AN
UNCAPPED AIR MASS AS INDICATED BY A DEEPENING CUMULUS FIELD ON
VISIBLE IMAGERY. CLUSTERS OF STRONG/ISOLATED SEVERE STORMS WILL BE
POSSIBLE WITH SEVERE WINDS THE PRIMARY THREAT...THOUGH MARGINALLY
SEVERE HAIL WILL ALSO BE POSSIBLE WITH THE STRONGEST STORMS.

IT REMAINS UNCLEAR WHETHER A WATCH WILL BE NEEDED GIVEN CONCERNS
ABOUT THE OVERALL SEVERE COVERAGE...AND CONVECTIVE TRENDS WILL
CONTINUE TO BE MONITORED.

..BUNTING/HART.. 07/21/2016

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...CLE...DTX...IWX...GRR...LOT...

LAT...LON   40778461 40818707 41348769 41768728 41798659 41998605
            42498469 42668376 42558311 41948323 41408255 41038258
            40888299 40778461 

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