“This year is remarkably different than the last two Novembers,” said Capital Weather Gang meteorologist Matt Rogers, who specializes in long-range forecasting. “The cold air supply in North America is a serious feature and we have to go back to 2014 to see something similar.”

The temperature pattern in the Northern Hemisphere has completely rearranged itself. Last year, North America was bathed in warm air and Siberia was frigid. Now it’s the opposite.

Cold air has infiltrated much of Canada and is also spilling south into the Lower 48. The cold has led to widespread snows.

Snow covers about 9 million square miles of North America this week compared with about 6 million square miles at the same time last year. Almost all of Canada is blanketed in snow, whereas the ground was bare in many areas a year ago.

In the Lower 48, snow covers nearly a quarter (22.9 percent) of the nation. Last year at this time, there was basically no snow (it covered a mere 0.6 percent of the Lower 48) and the quantity ranked as the lowest on record.

The cold and snow, so far, have mostly concentrated in the Pacific Northwest and Northern Rockies. A coating of snow (0.4 inches) even fell in Seattle on Friday, the most on record so early in November.

Downright frigid temperatures have gripped the Northern Rockies. Low temperatures in northern Montana fell as low as minus-20 Tuesday morning and high temperatures Monday were only in the single digits and teens.

While the core of the cold so far this month has focused in the northwest part of the nation, chilly air has begun to bleed eastward. Wet snow fell Tuesday in parts of Pennsylvania, including State College, and New York , as a cold front sank southward.

On Friday, a stronger, reinforcing blast of Arctic air is expected to plunge southeastward through the Great Lakes into the Mid-Atlantic and Northeast, bringing the coldest air of the season.

This early siege of cold will not endure, however, at least east of the Rockies. The National Weather Service’s eight-to-14-day outlook slightly favors milder-than-normal conditions for much of the eastern two-thirds of the country for the middle part of November — with the strongest signal in the South Central United States — which has recently experienced record hot weather.

However, Rogers sees the potential for a resurgence of cold for large parts of the nation later this month. He explained the current cold building over North America is the result of a big blocking ridge of high pressure over the Bering Sea, which is forcing the jet stream to dive south and deliver cold air.

By late November, Rogers said, the Bering Sea ridge may “hand off the baton to a blocking ridge in the North Atlantic” — which would also cause the jet stream to buckle, bringing the next blast of cold, potentially focused more on the Eastern United States.

Rogers said the cold air accumulating in Canada is ready to be tapped for any future Arctic blasts. “Having the cold air so nearby is pretty constructive for cold risk,” he said.

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