Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 341 PM EST Tue Feb 14 2023 Valid 00Z Wed Feb 15 2023 - 00Z Sat Feb 18 2023 ...Upper Midwest... Day 1... Low pressure over KS this afternoon is turning north and will lift over MN/northern WI tonight. The upper low will open into a negatively-tilted trough with plenty of warm air and rain along/ahead of the system. However, the wrap around band, already formed over western KS/central Neb to eastern SD will continue to strengthen and cool, allowing snow to develop that becomes heavy at times. With a 1027mb sfc high over MT, increased northerly to northeasterly winds will create blowing snow and blizzard conditions for parts of the eastern Dakotas into MN this evening (12Z HREF blizzard probs around 30% from 03Z-10Z). There is a risk that as the system lifts north the band could move long its axis of orientation and result in snowfall maxima. Day 1 snow probs are moderate for 4 or more inches from east-central SD (especially over the Coteau des Prairies) to the Boundary Waters of northern MN. As the system passes Wednesday morning, a shift to NW flow will bring lake enhanced snow to the south shore of Lake Superior. The northern WI coast also has moderate Day 1 probabilities for 4 or more inches. ...Four Corners, Central Plains, Upper Midwest/Great Lakes, Northern New England... Days 1-3... A positively-tilted trough shifting south through the Great Basin this afternoon is reinvigorated by a shortwave diving south over the PacNW and will close off a mid-level low over northern AZ tonight that tracks over the Four Corners early Wednesday and the southern Rockies Wednesday afternoon. Diffluence aloft coupled with mid-level height falls, lower-level FGEN, and upslope enhancement will yield a significant snowfall for the Mogollon Rim and smaller ranges northeast from there through the San Juans and Sangre de Cristos. Moisture anomalies are about normal, but the strong dynamics will make up for that. WPC snow probabilities for at least 8 inches of snow are high in these areas. Lee-side cyclogenesis occurs on the southern High Plains Wednesday with Gulf moisture wrapping around the low center (which shifts from northeast NM across the TX Panhandle), making for heavy snow bands over southeast CO, northern NM into the OK Panhandle and far southwest KS where Day 1.5 snow probabilities for 8 or more inches are moderately high. The low tracks over southern OK Wednesday night before shifting northeast over the Mid-South and tracking north of the Ohio River Thursday afternoon/evening. Frontogenetical banding persist north of the low center with moderate Day 2 probabilities for 8 or more inches stretching from central KS through southeast Neb/northwest MO over southern and eastern IA to the WI/IL border. This developing low will feature particularly heavy banding that moves along its axis of orientation and has the potential for producing a foot or more of snow in a narrow swath. This particularly becomes true as the system reaches the Great Lakes Thursday where northeastern flow will enhance snow totals over southern WI/northern IL and over portions of the north-central L.P. There will be plenty of cold air entering into this system with deep/saturated DGZ and high snow ratios. Day 2.5 snow probabilities are moderate for 8 or more inches over southeastern WI/far northern IL and across north-central L.P. Among 12Z guidance, the ECMWF and RDPS stand out for consistency and placement of the snow band (while the NAM is farther south and the GFS is farther north). Enough cold air is present to allow overrunning and a stripe of wintry mix, particularly beginning Wednesday night near the IA/MO border, continuing across Chicagoland and south-central L.P. of MI through Thursday. As of now the Day 2.5 ice probs over a tenth inch or more are limited to 10-30% for a narrow stripe over the south-central L.P. Jackson ...Key Messages for Feb 14-17 Winter Storm... --A winter storm reaching the Four Corners tonight will spread heavy snow across the Southern Rockies and Plains through Wednesday, continuing across the Upper Midwest and Great Lakes on Thursday. --Heavy snow rates and wind gusts above 40 mph will likely bring near-blizzard conditions for the Southern High Plains. Plan on considerable blowing and drifting of snow, very low visibility, near impossible travel, and impacts to infrastructure. Much colder temperatures, possibly near record lows over the Southwest, will follow this system. --Across the Central Plains and Great Lakes, expect a swath of heavy snow with intense snow rates between 1-2â€/hr and gusty winds. This will result in difficult to dangerous travel conditions Wednesday Night through Thursday.