At a Glance

Over one-quarter of the area of the Lower 48 had snow on the ground on Nov. 8.This is the largest areal coverage of snow on that date in at least 14 years, according to NOAA data.This is a sharp contrast to one year ago, which was one of the warmest Novembers on record.

Snow cover in the United States and North America is the most expansive for any early November in over a decade, despite recent warmth over parts of the Northeast.

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As of Nov. 8, almost 26 percent of the contiguous U.S. had snow on the ground, according to an analysis from NOAA's .

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This is the most expansive Nov. 8 snow cover in the Lower 48in NOHRSC's 15-year analysis, topping Nov. 8, 2011's 21-percent coverage.

In fact, snow cover over North America for this time of year since the middle of the past decade, as, director of seasonal forecasting at Atmospheric and Environmental Research (AER), a Verisk Business, brought to our attention.

The heaviest snow cover was found in the northern Rockies and theCanadian Rockies, but snow was also on the ground over a sizable swath of the High Plains, northern and central Plains, and dusted parts of the interior Northeast after a brief round of snow the previous day.

This included the on Nov. 8.

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This is all despite what has been an abnormally warm fall in much of the Great Lakes and Northeast –.

It's a sharp contrast to one year ago, when hardly any snow cover could be found over the Lower 48 states. dating to 1895, and record warmest in North Dakota, Idahoand Washington, according to NOAA.

Snow cover on Nov. 8, 2017, compared to that same date in 2016, when scant snow cover was seen anywhere in the Lower 48 states.

(NOAA/NOHRSC)

November started with a pair of potent snow events in the Cascades and Rockies.Additionally, cold air spilledthrough gaps in the Cascades to produce snowat sea level in western Washington.

The second of these events on Nov. 6 was the , the earliest such eventtherein 42 years. This was of the season.

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What Impact Might This Have?

In general, fresh snow cover helps refrigerate cold air masses coming south from Canada. These polar air masses moderate, or warm slower, if they're passing over more area with snow on the ground.

In the short term, this expansive snow cover may be contributing toa weekend plunge of record cold into the Northeast.

"I do think that the extensive snow cover is an important factorfor the record-breaking Arctic air predicted in the Northeast at the end ofthe week," said Dr. Cohen in an email to weather.com.

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Cohen saidweather models tend to underestimate the influence of snow coverandtend to be slow to catch onto theintensity of Arctic outbreaks.

by The Weather Company and NOAA each anticipate a colder-than-average December-through-Februaryin at least parts of the Northwest and northern Plains.

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December 2017 - February 2018 temperature outlook issued Oct. 20 by The Weather Company. The red contour in the South corresponds to higher probabilities of above-average temperatures. The darker blue areas in the Northwest and Upper Midwest have the highest odds of below-average temperatures. The light blue and orange contours show where temperatures may be slightly below or slightly above average, respectively.

This is consistent with La Niña winters generally being colder than average in the Northwest and parts of the northern Plains.

La Niña winters are also and thenorthern Rockies.

This early snow cover seems consistent with what you might expect in mostlate autumn periods headed into a La Niña winter, with 2016 being an exception.

Regardless, this is great news for , or those looking to build a solid base of snow by the Thanksgiving holiday weekend.

Jonathan Erdman is a senior meteorologist at weather.com and has been an incurable weather geek since a tornado narrowly missed his childhood home in Wisconsin at age 7. Follow him on and .