ZCZC SPCSWOMCD ALL ACUS11 KWNS 020921 SPC MCD 020921 MIZ000-WIZ000-MNZ000-021145- MESOSCALE DISCUSSION 1580 NWS STORM PREDICTION CENTER NORMAN OK 0421 AM CDT SUN AUG 02 2015 AREAS AFFECTED...PORTIONS OF ERN MN...WI...UPPER PENINSULA OF MI CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY VALID 020921Z - 021145Z PROBABILITY OF WATCH ISSUANCE...20 PERCENT SUMMARY...A RISK FOR AT LEAST ISOLATED SVR TSTMS WILL INCREASE DURING THE EARLY-MORNING HOURS. WHILE CONVECTIVE TRENDS WILL CONTINUE TO BE MONITORED...THE ISSUANCE OF A WW IS PRESENTLY UNLIKELY. DISCUSSION...RECENT MOISTURE-CHANNEL IMAGERY IMPLIES A SUBTLE MID-LEVEL SPEED MAX ADVANCING ESEWD ACROSS PARTS OF THE UPPER MS VALLEY. THIS IS LIKELY AUGMENTING LOW-LEVEL WAA TO RESULT IN A COMPACT ZONE OF 2-HRLY SFC PRESSURE FALLS OF 1.5-2.5 MB ACROSS THE SRN HALF OF MN INTO W-CNTRL WI. RECENT MOSAIC RADAR AND IR IMAGERY INDICATE DEEPER CONVECTION BEGINNING TO EVOLVE FROM ACCAS/PATCHY SHOWERS ACROSS CNTRL/E-CNTRL MN...WITH CG LIGHTNING STRIKES NOW OCCURRING ESE OF BRD. AS THE SUBTLY ENHANCED DEEP ASCENT CONTINUES TO OVERSPREAD MODERATE TO STRONG ELEVATED BUOYANCY -- FED BY EWD-DIRECTED FLUXES OF RICH LOW-LEVEL THETA-E AIR PRECEDING THE SPEED MAX -- CONVECTION MAY CONTINUE TO INCREASE IN COVERAGE/INTENSITY DURING THE NEXT FEW HOURS. ALSO...REMNANT CONVECTION FROM NRN MN TO WRN LAKE SUPERIOR MAY DEVELOP ESEWD INTO WRN UPPER MI. ALL OF THIS ACTIVITY SHOULD SPREAD ESEWD/SEWD THROUGH THE EARLY-MORNING HOURS...AND BE CAPABLE OF ISOLATED SVR HAIL OWING TO 35-50 KT OF MID-LEVEL WLYS/NWLYS ENHANCING DEEP SHEAR TO ENCOURAGE CONVECTIVE ORGANIZATION. GIVEN THE MODEST NATURE OF THE LARGE-SCALE ASCENT...CONFIDENCE IN A STRONG NOCTURNAL UPSWING IN CONVECTIVE COVERAGE IS PRESENTLY LIMITED. REGARDLESS...THE MODERATELY STEEP NATURE OF MID-LEVEL LAPSE RATES -- AROUND 7.0-7.5 C/KM IN THE H7-H5 LAYER PER EARLIER ABR/MPX RAOBS -- COUPLED WITH THE PRESENCE OF A MID-LEVEL PERTURBATION OFFER CONCERN FOR AT LEAST ISOLATED SVR POTENTIAL. IF GREATER CONVECTIVE COVERAGE WERE TO ENSUE THAN PREVIOUSLY ANTICIPATED...AND IF CONFIDENCE WERE TO INCREASE IN AMALGAMATING COLD POOLS BREEDING UPSCALE GROWTH OF A LARGER CONVECTIVE SYSTEM AND GREATER SVR-WIND POTENTIAL...WW PROBABILITIES WOULD NEED TO BE RE-EVALUATED. ASIDE FROM THAT LOW-CONFIDENCE SCENARIO AT PRESENT...NOCTURNAL STATIC STABILITY MAY BE DETRIMENTAL FOR DOWNDRAFT PENETRATION TO THE SFC...MINIMIZING THE OVERALL SVR-WIND RISK. ..COHEN/EDWARDS.. 08/02/2015 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...MQT...GRB...MKX...DLH...ARX...MPX... LAT...LON 46119445 46729279 46868873 45458748 43718843 43819133 44989412 46119445 NNNN