An Arctic blast across the Northern Plains, Midwest and Great Lakes on Saturday left millions of Americans under frostbite warning.

More than 17 million people were warned under the National Weather Service’s winter warnings on Saturday; these include 3.6 million lake effect snow warnings, 4.5 million freeze warnings, 8.5 million winter weather advisories and 1 million freeze warnings.

Affected areas ranged from the Great Lakes and Central Plains to the Appalachians, with most of these freeze warnings focused on the Southeast.

National Weather Service He warned that the Arctic air mass was showing the coldest temperatures since last winter. Wind chills in the Northern Plains and Upper Midwest are expected to drop below freezing Saturday morning. Parts of North Dakota could experience wind chills as low as minus 30 to 40 degrees, according to the agency.

Federal forecasters said the icy air mass also helped produce severe, travel-impeding lake-effect snow on the Great Lakes in northeastern Ohio, northwestern Pennsylvania, western New York and parts of northwestern New York.

The NWS said the highest snow accumulations are expected east of Lake Ontario, where some isolated areas around the Watertown, New York, area could be covered in up to 60 inches of lake-effect snow by early next week.

Lake-effect snow occurs when a cold air mass moves south from Canada and beyond the relatively warm Great Lakes, rapidly pulling some of the lake water into the atmosphere, creating fertile clouds and producing snow at the rate of 2 tons, the weather service says. 3 inches and more every hour.

By early Saturday evening, Watertown International Airport measured just one inch of precipitation during the day, and the weather service reported snow depths of 4 to 7 inches for the entire city. The weather service in Buffalo said more serious snowfall was still possible.

“100% chance of precipitation,” said an extended forecast for Watertown on Saturday. “A total of 15 to 21 inches of snow accumulation is possible overnight.”

Strong winds will likely cause blowing and drifting snow, as well as isolated power outages, and visibility will be greatly reduced due to near-whiteout conditions.

Gov. Kathy Hochul warned New Yorkers Saturday to avoid unnecessary travel. More than 100 National Guard soldiers are deployed in Western New York “to support local communities,” Hochul said in a statement.

“Please heed travel advice and look out for each other,” he said.

Hochul announced that Interstate 90 in western New York reopened to passenger vehicles Saturday afternoon after being closed Friday in response to snow closures near Pennsylvania.

He said commercial trucks are banned in both directions on the westernmost part of the interstate from exit 46. social media platform

A day earlier, the governor declared a state of emergency in several counties, including Erie and Oswego. Sometimes, snowfall rates of 3 to 4 inches per hour can be blinding and may be accompanied by thundersnow, a rare weather phenomenon that combines a blizzard with thunder and lightning, creating hazardous travel conditions.

By Friday night, more than 20 inches of snow had fallen along the shores of Lake Erie in parts of Ohio, Pennsylvania and New York, according to the NWS. Video taken Saturday morning showed snow-covered roads in Ashtabula, Ohio, making it difficult for drivers to use them.

Erie, Pennsylvania, recorded 30 inches of snow, the highest total ever, according to the agency.

A power outage at Philadelphia International Airport Terminal D on Friday night affected about 40 flights, but none were canceled. Power was restored to the terminal on Saturday afternoon.

Also Saturday, Pennsylvania Governor Josh Shapiro signed a disaster declaration that his office said will help those affected by lake-effect snow quickly receive response and recovery funds, according to a statement.

More than a dozen Pennsylvania National Guard members were deployed to assist the Erie County Emergency Operations Center in rescuing stranded motorists and moving abandoned, crashed or otherwise immobilized vehicles, he said.

More than 12 inches of lake-effect snowfall is possible in parts of the region from noon Sunday through 7 a.m. Tuesday, the weather office in Cleveland said Saturday.

Additional travel disruptions disrupted post-Thanksgiving travel plans, especially along Interstate 90 between Cleveland and Buffalo. Social media videos taken Friday show drivers stuck in bumper-to-bumper traffic on the interstate during a blizzard.

Storms of 3 to 6 feet will be possible through Monday and will continue to impact travel between Cleveland and Buffalo.

Buffalo Mayor Christopher P. Scanlon said the city is ready for snow.

“I can tell you that the city of Buffalo is prepared for weather moving forward, not just today, but for days and weeks to come,” he said at a news conference Saturday.

He said the city has opened three warming centers, which are open 24 hours a day for now, for those who need heat and shelter.

The National Weather Service said travel “may be very difficult or impossible” in points downwind of the Great Lakes.