ACUS11 KWNS 281234 SWOMCD SPC MCD 281233 MIZ000-WIZ000-MNZ000-281700- Mesoscale Discussion 0056 NWS Storm Prediction Center Norman OK 0633 AM CST Tue Jan 28 2025 Areas affected...the Upper Michigan vicinity Concerning...Heavy snow Valid 281233Z - 281700Z SUMMARY...A period of heavy snow, at rates on the order of 1-2+ inches per hour, appears possible in a corridor overspreading the central Upper Peninsula of Michigan vicinity by midday. DISCUSSION...Downstream of a low-amplitude short wave perturbation, accompanying an intense (110+ kt at 500 mb) jet streak digging east-southeast of the Canadian Prairies, lower/mid-tropospheric warm advection is overspreading the Upper Midwest into Great Lakes region. Associated forcing for ascent is becoming focused across the southwestern flank of an arctic air mass now entrenched across much of the Great Lakes region, particularly near a zone of strong lower/mid-tropospheric frontogenesis, which is forecast to shift from northwestern Ontario across the western Lake Superior and central Upper Peninsula of Michigan vicinity through 17-18z. Forecast soundings across this region indicate that the sub-freezing thermodynamic profiles are in the process of saturating, ahead of an ongoing band of moderate to heavy snow, which appears likely to be maintained through at least early afternoon. Temperatures appear within a few degrees of -15C through an initially deep layer from lower-levels into the 700-600 mb layer, where conditions will be most conducive to large dendritic ice crystal growth. Coinciding with maximizing lift associated with the frontogenetic forcing, it appears that this may support a 2-3 hour period of heavy snow rates on the order of 1-2 inches per hour. Forecast soundings also indicate that a layer a steepening mid-level lapse rates may be accompanied by the development of weak CAPE and embedded convective development with heavier snow rates possible. ..Kerr.. 01/28/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...APX...MQT...GRB...DLH... LAT...LON 48538911 47918791 46888619 46278519 45418590 44838674 45668731 46428796 46938875 47878969 48538911