Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 417 AM EST Wed Feb 15 2023 Valid 12Z Wed Feb 15 2023 - 12Z Sat Feb 18 2023 ...Southern Rockies, Central Plains, Corn Belt, Great Lakes, Northeast... Days 1-3... A closed low over the Four Corners this morning will move onto the western central High Plains (southwest KS) and start to shear out to the northeast toward the Corn Belt on Thursday as it becomes positively-tilted. Mid-level height falls, lower-level FGEN, and upslope enhancement will yield a significant snowfall for southeastern CO as lee-side cyclogenesis occurs over northeastern NM. Gulf moisture will surge northward today as the low moves through OK (700mb low through KS), wrapping moisture around its circulation into the colder air. D1 probabilities for at least 6 inches of snow are high (>70%) over parts of northern/northwestern KS and southeastern CO with upslope enhancement into the Raton Mesa. On D2, the low will track across the mid-MS Valley and into the Upper OH Valley with frontogenetical banding north of the low center that translates parallel to the low's track to the northeast. Models have been struggling with how much QPF may be realized on the cold side of the system but most CAM guidance showing potential for high single-digit snowfall totals embedded in a broader area of lower amounts as 850 FGEN lifts northeastward. WPC probabilities for at least 4 inches of snow are >50% from eastern Iowa northeastward across southern WI into northern lower Michigan. With northeasterly flow, some enhancement off Lake Michigan into southeastern WI and far northeastern IL is likely. Guidance has recently trended lower over Michigan, even as the low continues to deepen (though well to the southeast) and another shortwave moves through the western Great Lakes. Into D3, surface low will exit through northern New England, bringing the rain/snow line well north for mid-February. Generally lighter amounts are expected north of I-90 in NY and across portions of VT/NH/ME as the low quickly pulls away. Some lake effect will continue through D3 but will generally light. There, WPC probabilities for at least 4 inches of snow are low, generally <30%. South of the stripe of snow, a narrow area of mixed precip is likely from MO northeastward into southern Lower Michigan. Some sleet and icing are possible but amounts should be light with a transient ptype evolution. ...Pacific Northwest... Days 2-3... Mid-level trough in the northeastern Pacific will approach the Pac NW and split between a northern shortwave and a southern portion that will close off and sink southward along 130W well offshore. Cold front will weaken as it moves into Washington late Thursday (D2) with a few inches of snow for the Cascades, continuing into D3. Fracasso ...Key Messages for Feb 14-17 Winter Storm... --A winter storm over the Four Corners will spread heavy snow across the Southern Rockies and Central Plains today, continuing through the Corn Belt into the Great Lakes on Thursday. --Intense 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, expect heavy snow including intense snow rates between 1-2â€/hr and gusty winds. This will lead result in difficult to dangerous travel conditions today and tonight. --Heavy snow is then likely across portions of the Great Lakes Thursday. While some uncertainty remains in exact locations of the heavy snow, intense snow rates may lead to difficult travel.