Mesoscale Discussion NWS Storm Prediction Center Norman OK 0327 PM CST Wed Feb 22 2023 Areas affected...Parts of WI...lower MI...and far northern IL Concerning...Winter mixed precipitation Valid 3:27PM - 7:30PM CST SUMMARY...Mixed winter precipitation, including freezing rain, sleet, and moderate to heavy snow, will continue into the evening across portions of Wisconsin, lower Michigan, and far northern Illinois. DISCUSSION...Freezing rain and sleet are ongoing across southern Wisconsin, southern lower Michigan, and far northern Illinois in association with isentropic lift from a strong mid-level shortwave trough currently near the Mississippi River. As the trough and associated differential vorticity advection continue to approach the region, heavy precipitation will expand northward. Across southern portions of this region, short-term RAP guidance indicates warm temperatures aloft (approximately 5C at 850mb), which is favorable for freezing rain where surface temperatures are below freezing, though some sleet may mix in. Farther north, the entire column is below freezing, which is favorable for snow. Snow rates of around 1"/hour are possible, particularly as the differential vorticity advection results in deeper lift and a more saturated dendritic growth zone.
