Arctic Blast Is Sweeping East, Bringing First Snow of the Season

Temperatures are expected to plunge 10 to 20 degrees below normal, forecasters said, with the chill reaching deep into the South, where overnight lows could dip to freezing.

Brian Hurley, a meteorologist at the Weather Prediction Center, said on Sunday that temperatures had already started to fall, particularly in northern North Dakota, where readings had dipped to below zero.

“The cold air is going to continue to filter across the central part of the United States today,” he said. “Then tonight, and then on Monday, many areas in the Eastern part of the United States are really going to feel the effects.”

Conditions will also turn wintry and blustery as a storm system brings the first significant snow of the season to the Great Lakes, parts of the Northeast and the Appalachians. Some areas could get more than a foot of snow, while ice and frost could bring additional hazards.

Here’s what you need to know:

The Midwest

• The cold snap has already settled in, with the sharpest chill coming from late Sunday into Monday. More than 7.5 million people were under a winter storm warning as of Sunday afternoon.

• Chicago, Detroit, Milwaukee and Minneapolis will see highs in the 30s before a gradual warm-up on Tuesday. Topeka and Jefferson City, Kan., will reach the mid-30s to low 40s.

• Light snow will continue around the Great Lakes on Sunday, but “extremely fast and heavy” snowfall rates above three inches per hour are expected Sunday night through Monday, forecasters said.

• The greater Chicago area will see “intense lake effect snow” Sunday evening and into Monday with more than three inches of snow falling per hour, according to forecasters. That may extend to Lake and Porter Counties in Indiana. There is a strong probability of more than eight inches of total snowfall in some parts.

• Winter storm warnings cover northeast Illinois, northern Indiana, southwestern and northern Michigan through Monday. Marquette, Mich., and Chicago could get more than a foot of snow by Tuesday.

• Elsewhere near the Great Lakes, one to three inches of snow is expected, with local amounts up to five inches.

• Strong winds will cause blowing snow and low visibility across the Upper Midwest through Monday afternoon.

• Thundersnow — snow with lightning and thunder — is possible because of the sharp temperature contrast over the lakes.

• The Northern Indiana office of the National Weather Service warned that travel could be “very difficult” during Monday’s commutes.

The Northeast

• From late Sunday onward, the arctic air will begin to spread into the region.

• Overnight lows will fall into the 20s and 30s through Monday night, with highs only reaching the 40s.

• Winter weather advisories for a mix of freezing rain, sleet, snow and ice are in effect for northern and western New York State and northern Maine through Monday morning. Around one tenth of an inch of ice could form in those areas, affecting the Monday morning commute.

• Snow totals up to three inches are expected, with four to six inches possible in northern New York counties, including Chautauqua, Jefferson and Lewis.

The Mid-Atlantic

• The cold air arrives Sunday night, dropping lows near 20 degrees by Monday morning.

• Highs will remain in the upper 20s to low 50s Monday, before a widespread freeze Monday night, when lows fall into the teens and 20s.

• Snow showers will develop early Monday, lingering mainly in the mountains through Tuesday, with heavy snow forecast for western parts of Virginia as well as West Virginia.

• Four to seven inches are likely in higher elevations, with up to six inches in western Greenbrier County in West Virginia.

• Winter storm warnings are in effect from Sunday evening through Tuesday morning, with up to four inches possible elsewhere in the region.

• Winds could gust up to 40 miles per hour in West Virginia, causing blowing snow and reduced visibility.

• Frost is likely through Tuesday night and slick roads could affect Monday travel.

The South

• The cold moves in Sunday night, with temperatures expected to drop into the 50s, and for parts of northwest Georgia and Alabama, possibly into the 30s.

• Northern Florida will remain warmer, with highs into the upper 50s and low 60s on Monday, but lows could plunge to the upper 20s by Monday night.

• Mr. Hurley said some temperature records may be challenged, especially on Monday night into the early hours of Tuesday for Jacksonville, Fla., where 30 degrees is forecast. The current record low for Jacksonville on Nov. 11 is 35 degrees, which was set in 1977.

• Freeze warnings stretch from north-central Texas and Oklahoma to northwest Georgia, with lows near 19 degrees expected in parts of Arkansas and Oklahoma.

• Gusty winds will also make it feel even colder for much of the South, with wind chills falling into the teens and 20s by Monday morning.

• A freeze watch is in effect from central Georgia to the Carolinas from Monday night into Tuesday, when subfreezing temperatures are expected.

• Four to eight inches of snow is possible in the Smoky Mountains, with local totals of 10 to 12 inches. Strong winds may cause blowing snow in these areas, reducing visibility and travel could be hazardous during Monday commutes.

• Frost could reach as far south as northern Florida by Tuesday morning.

While temperatures are expected to fall as much as 20 degrees below average, the chill isn’t unusual for this time of year — except in parts of the South, Mr. Hurley said.

The cold will eventually loosen its grip, with temperatures expected to recover across the central United States after Monday and return to near normal in the East starting on Tuesday.

Johnny Diaz contributed reporting.