Travelers planning to hit the road this Thanksgiving holiday weekend should brace for a mix of snow, rain, and chilly temperatures. As of Friday, winter storm warnings were issued across the northern United States, with the Great Lakes region already seeing snowfall.

The National Weather Service reports that the storm warnings and advisories span from Montana to New York. Snowfall was expected to begin on Friday, continuing through the weekend, with Iowa and Illinois likely facing the heaviest accumulation. For west-central Illinois, forecasts predict six inches to a foot of snow from Friday night into Saturday night.

Meteorologists have noted that while the conditions are severe, they do not currently meet the criteria for a blizzard warning. Such a warning requires winds of at least 35 mph (56 kph), visibility under a quarter mile (400 meters), and conditions lasting over three hours.

This storm, which has already dumped snow over parts of the northern Plains and Great Lakes, persisted on Friday. By the storm’s end, areas downwind of Lake Superior in Michigan’s northern Lower Peninsula and downwind of lakes Erie and Ontario could see more than a foot of snow. Central New York state is also expected to receive up to a foot (30 centimeters) of snow.

On Friday, the weather service warned of potential snow squalls in the interior Northeast, which could bring brief but intense snowfall and create hazardous, whiteout conditions for drivers.

In the Pacific Northwest and the Rockies, a combination of snow and rain was expected Friday. By Saturday, the snow will taper off for the Rockies and northern Plains, but continue on to the Midwest.

To the south, storms — some of them heavy — are in the forecast, with some flash flooding possible Saturday in the western Gulf Coast.

Temperatures were well below average in the eastern and central parts of the country, with highs Friday expected in the 20s degrees F and 30s degrees F in the Midwest, the 30s and 40s in New England and Mid-Atlantic areas, and the 40s and 50s in the Southeast.

The snowy weather on Thanksgiving brought a number of vehicle crashes in western Michigan.