Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 353 PM EST Wed Feb 15 2023 Valid 00Z Thu Feb 16 2023 - 00Z Sun Feb 19 2023 ...Central Plains, Corn Belt, Great Lakes, Northeast... Days 1-2... An upper low over the Southern Rockies will shift a bit east-northeast tonight as it moves over the south-central Plains before opening into a positively-tilted trough as it moves into the Midwest Thursday. 12Z Guidance certainly trended south/weaker in the snowband intensity. However, height falls, lower-level FGEN, Gulf moisture and cold Canadian air spilling down the Plains into the snow zone still provide a robust threat for mesoscale snow bands and locally heavy snowfall. Day 1 snow probabilities for 6 or more inches are 40 to 70% from the Neb/KS border, across southeast Neb, much of southern and east-central IA, and along the WI/IL border. Lake enhancement off southern Lake Michigan makes for a greater heavy snow threat in southeast WI/far northeast IL. Additionally, enough cold air gets in place below the warm air advection to allow stripes of sleet and freezing rain south of the heavy snow. Day 1 freezing rain probabilities for a tenth inch or more area 10 to 25% over northeast MO into western IL and over southern/southeast MI. 12Z guidance continues to not have latitudinal consensus on where the bands set up over the L.P. of MI Thursday afternoon/evening. There is still decent fgen forcing along with lake enhancement from Huron to contend with. Day 1.5 snow probabilities for 6 or more inches are generally 30 to 50% north from I-94 to the Tip of the Mitt which is a broad area and locally higher totals expected inside there. Guidance has shifted east a bit to a surface low track along/just off the northern New England coast, but the rain/mixed/snow line is still well north for mid-February. Day 2 snow probs for 6 or more inches are moderately high for northern Maine with single digit risk for a tenth inch or more of ice over northern New England. Lake effect snow in the wake of the system is rather limited, though northerly flow down Lake Michigan should bring a single band into northwest IN Thursday night into Friday. Day 2 snow probabilities for 4 or more inches are around 10% over Gary/Portage. ...Pacific Northwest... Days 2-3... Confidence increases on the mid-level trough currently extending from the Gulf of Alaska will spin off a low that stays off the West Coast while tracking south, eventually approaching southern CA/the Baja early next week. Day 2 snow probabilities for 6 or more inches are low over the northern WA Cascades as the sheared northern end of the trough pushes east over BC/WA Thursday night. Snow levels at this time are around 2000ft, so there is a wintry impact potential for the WA Cascades passes. Jackson ...Key Messages for Feb 14-17 Winter Storm... --Snow is expected to diminish across the High Plains this evening. However, windy conditions, with blowing and drifting snow, will reduce visibility and create dangerous travel conditions. --Across the Central Plains into the Midwest, expect heavy snow, including intense snow rates between 1-2"/hr. Gusty winds and blowing snow may reduce visibility. A stripe of mixed precipitation, with sleet and freezing rain, is likely south of the heavier snow. Difficult to dangerous travel conditions are expected tonight into Thursday. --Locally heavy snow is then likely across portions of the Lower Peninsula of Michigan Thursday afternoon/evening. While uncertainty remains in the exact locations of the heavy snow, intense snow rates may lead to difficult travel.