Winter Storm Tracker: Cold, Snow and Rain to Sweep US and Canada

The heaviest snowfall, according to forecasters, is likely to occur between Wednesday night and Friday over the Great Lakes, where the total depth could exceed a foot. Wind gusts of more than 50 m.p.h. will create near-zero visibility, leading to what the Weather Service described as “dangerous, to at times impossible, land and air travel.” There is also concern for tree damage and widespread power failures.

But the snow doesn’t have to be heavy to become dangerous. Snow combined with 50 m.p.h. winds across the Plains, through the Midwest and into the Great Lakes will create blizzard conditions with any snow falling or on the ground already.

The potential for this to be a “bomb cyclone,” which is meteorologist jargon for a storm system that drops 24 millibars (a measure of air pressure) or greater in 24 hours or less, will lead to extreme winds across the region.

Cities across the region, including Cleveland and Peoria, Ill., are preparing to open warming centers to allow residents to seek shelter during the storm.

Northeastern United States

By late Thursday or Friday, the storm system will have reached the Mid-Atlantic, bringing with it moderate to heavy rainfall of one to three inches, forecasters say. Strong southerly winds, combined with the new moon-tide cycle, could also bring coastal flooding from northern New Jersey to northeast Massachusetts, the Weather Service said.

In parts of Vermont and Maine, heavy rain over a fresh snowpack could lead to flooding, according to the service. Parts of the central Appalachians may also receive light freezing rain and locally heavy snowfall on Thursday morning.

On Friday, as the Arctic cold front races eastward, temperatures will drop suddenly from the mid to upper 50s down to the 20s or the teens, the service said. This rapid plunge in temperature can flash freeze wet surfaces like roads and pavements, creating hazardous conditions.