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An extremely potent Arctic cold front and weather system in the upper levels of the atmosphere will effectively postpone spring for several days at least across the Midwest and Northeast beginning on Saturday. 

The storm system that will be responsible for causing accumulating snow from southern New England to the Great Lakes states on Saturday night into Sunday, and potentially again next week, is part of a splinter group of the polar vortex rotating as far south as the Canada-Vermont border. 

SEE ALSO:With a collapsing West Antarctica, sea level rise may be twice as high as we thought

Thanks to a massive, blocking ridge of high pressure over British Columbia during the past week, the airflow in the mid and upper levels of the atmosphere across northern Canada turned more northwesterly, driving cold air and disturbed areas of weather southeast, toward the U.S. 

>90% 500mb heights outside climatology (NAEFS) across western Canada from amplified ridge over the eastern Pacific pic.twitter.com/XghZ3hqMEX

— Zack Labe (@ZLabe) April 1, 2016

The high pressure dome over British Columbia is itself extraordinarily strong, so it follows that conditions downstream from it might be unusual too. 

While the details may change, computer models are consistently signaling the arrival of a potent weather system that could bring damaging winds in excess of 60 miles per hour to much of Illinois, Michigan, Ohio, Pennsylvania, New York State and New England during the weekend. 

So you might be hearing about snow in the NE this weekend;Room here for snow-totals to be MUCH higher than expected pic.twitter.com/fUSfZdteSy

— Michael Ventrice (@MJVentrice) April 1, 2016

Accompanying these winds will be plunging temperatures, tumbling from the mid-70s Fahrenheit on Friday to the upper 20s and low 30s by Sunday and Monday morning in areas including Allentown, Pennsylvania, New York City and Boston. 

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500 millibar heights and vorticity projection for Sunday morning, showing the strong disturbance (red fist-like appearance) moving through the Northeast.Credit: WEATHERTIDBITS

Bernie Rayno, a meteorologist at AccuWeather in State College, Pennsylvania, remarked on Twitter and in an online video that he doesn't think the general public in the Northeast and Midwest is well-prepared for what is coming this weekend. 

"You’re going to get up in the morning, look out the window, and you’re gonna say 'holy crap,'" he said, specifically referring to the possibility of accumulating snow on Sunday morning.

“It’s a holy crap situation."

The National Weather Service in New York City has already issued a high wind watch for Saturday night into Sunday morning, and is forecasting rain showers to transition to snow showers overnight. At least two more storms, one potentially involving wintry precipitation, are slated to move through during the week, too. 

Surface weather map for Sunday morning showing snow falling in New England.Credit: Weathertidbits

The National Weather Service forecast office in Boston is advertising a "winter-like" weather pattern in its morning forecast discussion, highlighting "two potential accumulating snow events" including one with "thundersnow possible." 

Thundersnow is the ultimate prize for any winter weather fan, and it has been in short supply this winter in much of New England.

The strength of the upper level weather system rotating through New England on Saturday into Sunday morning suggests the potential for a surprise jackpot of at least several inches of snow somewhere from Massachusetts to Maine.

The air temperature in the mid-levels of the atmosphere on Sunday morning is predicted to be three standard deviations below average for this time of year, which suggests a very unstable air mass capable of spawning heavy snow showers and possible thundersnow. 

Another storm on Monday threatens to bring more accumulating snow to southern New England, with much colder-than-average conditions lasting through much of the week. 

(责任编辑：焦點)