ZCZC SPCSWOMCD ALL ACUS11 KWNS 261622 SPC MCD 261622 MIZ000-WIZ000-ILZ000-261815- MESOSCALE DISCUSSION 0783 NWS STORM PREDICTION CENTER NORMAN OK 1122 AM CDT TUE MAY 26 2015 AREAS AFFECTED...NERN IL/ERN WI/PORTIONS OF CENTRAL UPPER MI AND INTO NRN AND WRN LOWER MI CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE VALID 261622Z - 261815Z PROBABILITY OF WATCH ISSUANCE...40 PERCENT SUMMARY...SEVERE THREAT IS EXPECTED TO VERY GRADUALLY INCREASE ACROSS THE DISCUSSION AREA THIS AFTERNOON -- INCLUDING RISK FOR ISOLATED/BRIEF TORNADOES. WW MAY EVENTUALLY BE NEEDED. DISCUSSION...LATEST VISIBLE SATELLITE LOOP SHOWS SOME BREAKS IN THE EXPANSIVE CLOUDINESS ACROSS THE UPPER GREAT LAKES REGION -- MAINLY OVER NRN WI AND INTO PORTIONS OF UPPER MI...AS WELL AS OVER MUCH OF LOWER MI ATTM. SOME HEATING THROUGH THE BREAKS IN CLOUD COVER HAS RESULTED IN MODEST DESTABILIZATION...WITH UP TO 500 J/KG MIXED-LAYER CAPE NOW INDICATED IN THE MOST CLOUD-FREE AREAS. AS A MID-LEVEL VORT MAX CENTERED CROSSING THE NRN MO/SRN IA VICINITY CONTINUES SHIFTING...LARGE-SCALE ASCENT WILL CONTINUE TO OVERSPREAD THIS AREA. A BAND OF SHOWERS/EMBEDDED THUNDERSTORMS IS SPREADING NEWD ACROSS SRN WI/NRN AND ERN IL ATTM...WITH A STRONGER STORM OR TWO ALSO INDICATED AHEAD OF THIS BAND OVER S CENTRAL WI. WITH VEERING/INCREASING FLOW WITH HEIGHT AHEAD OF THE BAND SUFFICIENT FOR UPDRAFT ROTATION /AND A FEW CELLS EXHIBITING VERY WEAK ROTATION PER WSR-88D SRV/...EXPECT SEVERE/BRIEF TORNADO RISK TO GRADUALLY/MODESTLY INCREASE OVER THE NEXT FEW HOURS AS STORMS EXPAND/OVERSPREAD THE DISCUSSION AREA. WHILE WW IS NOT IMMINENT...WE WILL MONITOR HEATING/DESTABILIZATION /AND ANY ASSOCIATED INCREASE IN CONVECTIVE INTENSITY/ ACROSS THE AREA WHICH COULD EVENTUALLY WARRANT WW CONSIDERATION. ..GOSS/MEAD.. 05/26/2015 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...DTX...APX...GRR...MQT...GRB...LOT...MKX...DVN... ARX... LAT...LON 44409006 45628916 46458787 45918442 44478305 43728397 42378629 41118865 42068927 42859013 44409006 NNNN