First arctic blast of season to shift weather patterns across US

By Linda Lam for Weather.com

The record warmth that much of the U.S. experienced this fall will just be a distant memory this week. A change is coming, courtesy of the first arctic blast of the season, arriving first in the western states early in the week, then spreading east throughout much of the Lower 48 into next weekend.

The pool of arctic air that is set to invade the Lower 48 is currently located in Alaska and northwest Canada. A pattern change will dislodge that arctic air and allow it to spill southward in the days ahead.

Specifically, a southward dip in the jet stream, or upper-level trough, will dig southward from the Gulf of Alaska and western Canada into the western U.S., and will then slide eastward as the week progresses. High pressure at the surface will then dive southward, allowing arctic air to spread into parts of the Lower 48.

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10 of the biggest snowstorms in history

10. The Knickerbocker Storm of 1922

View of a car buried in snow during the so-called Knickerbocker Storm, a blizzard that dropped 28 inches of snow on Washington DC, January 28, 1922. The storm, which also affected a large portion of the Eastern Seaboard, was named after the collapse of DC's Knickerbocker Theatre, caused by the excess weight of the snow on the structure's roof, which resulted in 98 deaths and 113 injuries; later, both the building's owner and architect committed suicide.

(Photo by Herbert A. French/Buyenlarge/Getty Images)

9. Blizzard Of 1888

A man stands by a snow hut, after the Great Blizzard of 1888, with U.S. Capitol in background, Washington, D.C. According to History.com, 55 inches of snow piled up in some areas and hundreds of people were killed.

(Photo by Buyenlarge/Getty Images)

8. The Blizzard of 1996

The Blizzard of '96 was a severe nor'easter that paralyzed the U.S. East Coast with up to 4 feet of wind-driven snow from January 6 to January 8, 1996. It is one of only two snowstorms to receive the top rating of 5, or 'Extreme', on the Northeast Snowfall Impact Scale. Looking west down Penn. Ave from the US Capitol during the Blizzard.

(Mark Reinstein/Corbis via Getty Images)

7. 2008 Blizzard in Tibet

Journeying outside of the Unites States, Tibet got a surprise storm that lasted 36 hours and dropped upwards of five feet of snow causing buildings to collapse and at least seven deaths

(Photo credit: Getty)

6. 1959 storm on Mount Shasta

Number six is the storm on Mount Shasta in California in 1959 which unloaded 189 inches of snow on the locals and is considered the largest snowfall from a single storm in North America according to NOAA.

(Photo by Frederic Lewis/Archive Photos/Getty Images)

2. Blizzard of 1977

At number two is the blizzard of '77 in Buffalo, New York. Powerful and sustained winds created massive snow drifts.

(Photo by Ira Block/National Geographic/Getty Images)

5. Blizzard of 1971

Next is the Eastern Canadian Blizzard of 1971. It is said the event closed down the Montreal Forum, canceling a Montreal Canadiens hockey game, something that hasn't occurred since the flu epidemic of 1918.

(Photo by Dave Norris/Toronto Star via Getty Images)

4. New England Blizzard of 1978

At number four is the New England Blizzard of 1978. Stalling over New England, this storm struck during the day, dropping over 27 inches of snow and stranding many at schools, businesses and others in their cars.

(Photo by David L Ryan/The Boston Globe via Getty Images)

3. The Great Snow of 1717

Then there was the Great Snow of 1717 over the New England Area. With five feet of snow already on the ground, around four more fell on top of that creating drifts as tall as 25 feet, burying entire houses.

(Photo via Getty Images)

1. Blizzard of 1967

But the storm to top them all is the Blizzard of 1967. Laying waste to the Midwest, this storm took 76 lives, set the record snowfall for Chicago with 23 inches and was preceded by a severe tornado outbreak with temperatures in the 60's.

(Photo by Robert Abbott Sengstacke/Getty Images)

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This will be the first arctic air mass of the season for the U.S., just in time for the first full week of December.

How Cold Will It Get, and When?

The coldest temperatures of the season, so far, are expected to arrive in the week ahead. Big temperature drops are anticipated, with highs and lows falling 20 to 30 degrees.

These very cold conditions will first be felt in the northern Rockies on Monday and will spread through much of the West and into portions of the northern and central Plains by Tuesday.

The first sub-zero temperatures of the season for some locations are expected Tuesday through Thursday mornings from the Rockies to the northern Plains.

High and low temperatures will be as much as 35 degrees colder than average. This translates to high temperatures below freezing for much of the West and into the northern and central Plains and Midwest. In fact, highs will struggle to reach double digits midweek in parts of the northern Rockies and northern Plains.

Even with these very cold temperatures, widespread record lows are not expected.

It will be windy as well, which will make it feel even colder than what the thermometer reads, resulting in brutal wind chills.

In addition, snow will accompany the cold temperatures in some locations.

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Arctic air will continue to plunge through the Plains and into the Midwest midweek. Above-average temperatures will be replaced with below-average readings. Highs will drop from the 40s to the 20s for much of the Midwest.

Late in the week, the colder conditions will reach the East Coast.

At this time, it appears that temperatures will not be as cold for the East as for the West and Plains. However, it will feel more like winter.

High temperatures will drop from the mid-40s to the low to mid-30s for much of the Northeast, and many areas of the South will see highs in the 50s and 60s replaced with highs only in the 30s and 40s.

The chilly conditions will reach all the way to Florida. Temperatures in central Florida will only reach the upper 50s by late week, compared to 80s early in the week. Lows in the 40s may push into the central Florida peninsula, including Orlando, by Saturday morning.

Check back to weather.com for forecast updates as we get closer to this expected cold blast.

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