The National Weather Service's prediction for morning lows Friday. (WeatherBell)

What’s worse than a temperature of minus-13 degrees? How about a wind chill of minus-49! That’s how residents of Grand Forks, N.D., started their day Wednesday. Temperatures fell from near freezing to minus-9 in just six hours amid 50 mph gusts and a “ground blizzard.” It heralded the leading edge of bone-chilling Arctic air that’s sweeping east.

The deep freeze will mark the coldest stretch of the season for some, with temperatures plummeting more than 40 degrees in just 12 to 24 hours’ time in many spots. Grand Forks hit a low of minus-28 early Thursday (some locations nearby fell as low as minus-37) as wind chill alerts stretch across much of the Upper Midwest and Northern Plains.

The National Weather Service warned that “the dangerously cold wind chills could cause frostbite on exposed skin in as little as 10 minutes.” And the wind chill in northern Minnesota fell as low as minus-50 early Thursday.

Temperatures on Thursday morning were modeled to be up to 40 degrees below average. (WeatherBell)

Eventually, this intense, albeit brief, icy air mass will make it all the way to the Mid-Atlantic and New England — though in a moderated form.

Along the cold shot’s southern periphery, an insurgence of moisture from the Deep South was helping make for a narrow strip of snow from the Chicagoland to Maine. Earlier on, a so-called ground blizzard had raged in the Red River Valley of the Dakotas, where strong winds lofted previously fallen snow.

The instigator behind the impending cold is not a low-pressure system, the type of setup we usually associate with unwelcome weather — including storms. Instead, the culprit for the cold is a dome of high pressure sagging south from Manitoba, Canada. The air it transports has origins as far away as the East Siberian Sea in the Arctic Ocean. Cold air is denser than warm air, and subsequently is compressed toward the ground, raising surface pressure.

NOAA's HYSPLIT model illustrates the Arctic origins of the air mass chilling the nation's center. (NOAA)

That high Thursday morning was anchored over the Dakotas, spilling the coldest air south over the Upper Midwest, Corn Belt and central/northern Plains. Minneapolis plunged to minus-10 (with a wind chill of minus-30) and Kansas City dropped to a mere 3 degrees early Thursday, the coldest temperature observed there this season. The temperature fell swiftly since midnight, at which time the mercury stood at 19 degrees. And air pressure climbed as the Arctic high sauntered south — from 1012.3 millibars to 1028.5 in just 12 hours.

In Omaha, the temperature fell to minus-4 overnight, also its coldest reading of the season. It’s nowhere near a record though — the city hit minus-22 degrees on Feb. 13, 1905.

The cold front had made it as far south as Oklahoma by Thursday morning, the Sooner State hosting a substantial temperature gradient as the front passed through. Broken Bow, in the state’s southeastern corner, stood at a comparatively balmy 40 degrees, while Newkirk, about 275 miles to the north-northwest, had nose-dived to just 10 degrees.

By Friday morning, the high will be anchored over the central Mississippi Valley as it inches into Illinois. Already, morning lows hit minus-7 in Sioux City, Iowa, and a staggering minus-27 in Park Rapids, Minn., on Thursday morning. The most severe cold will soon eye the Great Lakes. Chicago is forecast to flirt with zero early Friday morning. The Windy City has not dipped below 2 degrees this season, which occurred Jan. 19.

A look at Friday morning's low temperatures as predicted by the National Weather Service. (WeatherBell)

Indianapolis and Detroit could also find themselves in the single digits to start their Friday, although those are the single digits above zero.

Ahead of the cold, a bit of light snow had developed along the southern and eastern fringes of Lake Michigan.

In the East, cuddle weather arrives just in time for Valentine’s Day. The abrupt cold front will pass through Friday for folks in the nation’s capital, Philadelphia, Baltimore and New York. That will make early Saturday the chilliest.

In Washington, D.C., the temperature might actually make it to near 20 degrees. That may not sound impressive, but it hasn’t fallen below 22 degrees this season. That’s only happened once before, during the winter of 1931-32. The local National Weather Service wrote that “this winter’s lack of extreme cold is almost unprecedented.”

Highs there will struggle to escape the mid- to upper 30s on Friday and Saturday.

A look at how much colder it could be Friday morning vs. early Thursday, as predicted by the American GFS model. (WeatherBell)

In extreme northern New England, daylight could dawn Friday on regions 40 degrees colder than they were at the same time Thursday morning! Take Plattsburgh, N.Y., for example. It was 32 degrees as the sun rose Thursday morning; on Friday, it could be 5 degrees below zero.

The cold shot, while in some places packing a punch, will be brief. By Sunday, most locales will rebound to near or above seasonable norms. And with the polar vortex keeping to itself in the northernmost confines of the Arctic, those of us in the Lower 48 are unlikely to be dealing with a prolonged batch of cold anytime soon.