Major Winter Storm System- Heavy Snow and Nor'easter

A couple of rounds of winter weather forecasted to impacts parts of the Midwest and the Northeast. A prolonged winter storm is expected to begin across parts of the Midwest beginning this evening and persisting into early next week. Heavy snowfall expected to fall across parts of the midwest tonight into Sunday, with snow also spreading across the Appalachians into the Mid-Atlantic. This system will then get hung up on the Appalachian with a new low-pressure system forming along the Atlantic Coast becoming a Nor'easter type storm system which will bring heavy snowfall to the Northeast. Uncertainty still remains with the low track but we will continue to monitor weather models and make adjustments for this region. Across the Midwest snowfall rates of 1-2" an hour are possible across the region. This will cause reduced visibility across the area for periods of time, which along with heavy snowfall will create hazardous travel conditions across the region. Snow will be wet and heavy so power outages could be possible across the region too. Across the Mid Atlantic and into the NE, snow starting tonight with freezing rain also likely across ports of WV, NC, and VA. We also continue to monitor for a second system is set to develop move across the US at the beginning of February bringing another round of snow to the Central Plains and into the Upper Midwest.

An area of energy (MSWT) is ejecting out of the Four Corners will sharpen into a negatively tilted trough and close off over Missouri this

evening before lifting towards lower Michigan by Sunday afternoon.

This feature will be accompanied by modest but coupled jet streaks driving upper-level support and divergence aloft as the system ejects out over the Rockies which will drive surface cyclogenesis from the TX Panhandle northeast towards the lower Ohio Valley through Sunday.

Downstream of this trough, mid-level divergence will rapidly increase, which combined with low-level WAA will drive an expanding precipitation shield across the Mid-MS Valley northeastward into the Great Lakes and Ohio Valley due to isentropic ascent with moisture wrapping around the deformation zone into the comma head of this developing mature mid-latitude cyclone. As the precip lifts northward, it will encounter slowly retreating cold high pressure. The isentropic ascent of the moist air atop this high will spread snowfall from eastern IA into southern WI, northern IL, northern IN, and into OH. This area of ascent accompanied by upper-level support from the shortwave, frontogenesis band head of the warm front and divergence aloft will drive heavy snow rates of 1" an hour or greater as noted by HREF probabilities. While the developing TROWAL may remain modest and somewhat south of the axis of heaviest snow, a prolonged period of moderate to heavy snow north of the eastward shifting 700mb low will likely produce heavy accumulations, although some moderation is likely due to the heavy wet nature of the snow.

To the south in the warm sector, this region will be warm enough for all rain, there is likely to be a stripe of heavy snow on the northern edge of this precipitation shield north of the 700mb low track near the TWORAL or the trough of warm air aloft, with a narrow band of modest freezing rain in between.

WPC probabilities on D1 are high for 6 inches in northeast IL into northwest IN, shifting east across northern IN into western OH. There is likely to be some isolated totals approaching 10", with the highest amounts possible in the Chicago vicinity due to some lake enhancement as easterly flow moves across Lake Michigan enhancing moisture due to the fetch across the lakes.


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72 Hour Snowfall Forecast Model Charts

Hand Drawn Forecasted Accumulated Snowfall Maps


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