Winter ended weeks ago, but blizzard warnings were in effect on Monday for parts of three states across the northern Plains as AccuWeather forecasters warned that a “storm of the century” could unfold across the region this week. Elsewhere, winter storm warnings and watches dotted the weather map across the northern tier of the United States as a storm system, which came ashore in the Pacific Northwest, was expected to track eastward.

The storm system brought snowfall to Portland, Oregon, on Monday, the first time the city has ever recorded measurable snowfall in the month of April, according to AccuWeather Meteorologist Renee Duff.

As of Monday morning local time, 1 inch of snow had been tallied at Portland International Aiport. Records there go back to 1940, according to the National Weather Service. Interestingly, the snow on Monday was not even close to the latest snowfall ever recorded in Portland. The city got snow on May 8, 1953, when a half-inch was measured.

Since last week, AccuWeather meteorologists have been monitoring for the potential for a large storm to track from the Northwest through the northern Plains where it is expected to strengthen quickly, bringing widespread gusty winds, blizzard conditions and substantial snow totals to the northern Plains.

There is the potential for this storm to bring record snowfall for the month of April to cities such as Bismarck and Grand Forks, North Dakota. A record-setting, late-season snowstorm in 1966 unloaded up to 2 feet of snow to these areas, and similar totals are expected from this week’s storm, making it likely this will rank as “one of the worst storms in recent history,” AccuWeather Senior Meteorologist Adam Douty said.

The combination of high winds and snow will shut down roads and interstates across many areas, and snowdrifts may reach up to 20 feet.

The large storm is expected to move eastward from the Rockies into the center of the country Monday night into Tuesday where it will clash with warm, humid air in the East from the Gulf of Mexico, serving as the storm’s moisture source. Meanwhile, a southward dip in the jet stream will allow cold Canadian air to filter into the Southwest, the Rockies and northern Plains, setting the stage for a more robust amount of snow as the week progresses.

On the northwest side of the storm, heavy accumulating snow is likely to begin on Monday night and continue through Thursday, especially for portions of the northern Plains into the Canadian Prairies.

Areas in the northern Plains and high terrain of the Rockies can pick up more than a foot of snow. Winds are expected to be strong enough to produce blizzard conditions later on Tuesday through early Thursday.

The storm will bring snowfall to an expansive swath of the nation from Idaho and Utah across western Nebraska into the Arrowhead of Minnesota by the time the storm is all said and done. Those places that don’t get the heaviest accumulation totals are expected to pick up a few inches of snow.

The exact track of the storm will determine where the heaviest snow extends from the Rockies to the northern Plains. However, communities from Bismarck, North Dakota, to Winnipeg, Manitoba, and well into Ontario, could receive over 18 inches of snow with 2 to 3 feet in spots. AccuWeather meteorologists are forecasting an AccuWeather Local StormMax™ of 40 inches (100 cm).

“In the hardest-hit areas, people need to plan to be self-sufficient for several days with enough water, food and supplies as it may take considerable time to clear roadways from the snow that will fall and then blow and drift,” AccuWeather Chief Meteorologist Jonathan Porter said. “Power outages may occur as well, adding more challenges for people in these areas.”

In Grand Forks, North Dakota, the snowiest April ever on record was in 1970 when 17 inches of snow fell. It is not out of the realm of possibility that this snowstorm alone could produce that much snow there. The highest three-day snowfall total ever recorded in South Dakota during the month of April was in Custer, where snow ending on April 20, 1920, piled up to 44 inches.

While the specific track of this system can shift, confidence continues to increase that blizzard conditions will occur from the Front Range of the northern Rockies extending northeast through the Dakotas into northwestern Minnesota.