Wintry weather to return: Arctic air to whisk away record-breaking warmth in East, Midwest
Record-challenging warmth will give way to Arctic cold waves that could bring a return of snow in parts of the central and eastern United States in the upcoming weeks. A polar vortex displacement will be involved.
This robot from the company Reflex Robotics helped shovel snow off the streets of New York City on March 4.
Winter is staging a comeback later this week across the Northeast and Midwest following several days of unusual warmth. Unlike the persistence from late January to February, colder air will come in waves with warm surges in between, and March sunshine lending a hand.
Record-challenging warmth both day and night started the week
In much of the eastern half of the nation, temperatures surged to their highest levels since last autumn during the first part of this week. Dozens of locations from the Ohio Valley to the Gulf and Atlantic coasts came close to or even set record daytime highs and record high minimums (warmest overnight lows).
"The temperature reached 80 F in New York City's Central Park on Tuesday, which was the earliest 80-degree reading on record," said AccuWeather Senior Meteorologist Bob Larson. "The old record was 85 on March 13, 1990." Records in New York City date back to the mid-1800s.
Higher humidity and thunderstorms will also spread northward from the central Plains into the Ohio Valley, the mid-Atlantic and parts of the South through midweek, giving some residents a taste of summer despite the calendar saying March.
Large storm to initiate a change
A potent storm and its trailing cold front began sweeping away the warmth Tuesday night and moved east across parts of the Mississippi Valley Wednesday. The front is forecast to reach the Southeast by Thursday.
The storm unleashed a dangerous severe weather outbreak across parts of the central and eastern United States as it tracked eastward.
Along the storm's northern edge, a significant ice and snow event unfolded. Ice accumulation on power lines led to widespread power outages in Canada. As of early Thursday morning, around 165,000 customers were without power in the province of Quebec.
Is sneaky snow from North Carolina to Maryland possible Thursday?
As colder air rushes in behind drenching showers and gusty thunderstorms in parts of North Carolina, Virginia and Delmarva Thursday, a period of wet snow may occur. Wet snowflakes may even mix in on the tail end of the rain as far to the northeast as Delaware, New Jersey, southeastern New York and southern New England.
Temperatures starting the day in the 60s and 70s will be swapped by early-evening temperatures in the 30s to near 40.
Cold shocks, spring setbacks on the way
As the cold front reaches the Atlantic Coast later this week, some areas' daytime highs will plunge by 20-30 degrees. Highs in the 60s, 70s and 80s will be replaced by highs in the 40s, 50s and 60s.
The temperature swing from early-week highs to late-week lows could be as much as 60 degrees Fahrenheit in some cases.
Where winter storms occur, the strength of the March sun may limit snow accumulation on roads and sidewalks during the middle of the day. However, at night and during the morning commute, as surfaces cool and snow falls steadily, travel could become slippery.
While the stretch of temperatures above the historical average that began more than a week ago continued into Wednesday, the temperature pattern beyond that is likely to bring several days of below-average temperatures during the latter part of the second week and into the third week of March.
Multiple waves of cold air will invade the Central and Eastern states with the main impacts on the Midwest and Northeast.
The first push of colder air will hack down the warmth late this week. Subsequent waves of colder air from Sunday and Monday in the Midwest and the Northeast Tuesday and Wednesday will have progressively more punch.
That cold blast will roll along in the wake of a large storm that will spread vast areas of snow and a wintry mix to the North-Central states and interior Northeast.
What's driving the upcoming cold surges?
Not every cold wave is tied to the polar vortex, but these will be.
Another displacement or weakening of the polar vortex is underway, which can allow bursts of Arctic air to spill into the Midwest and Northeast at times, according to AccuWeather Lead Long-Range Meteorologist Paul Pastelok.
"There will be an active storm track with snow and ice along the U.S./Canada border this week," Pastelok said. "The wake of these storms will help draw colder air farther south. As the pattern evolves, a storm sometime from March 16-19 can bring mixed snow, ice and rain to parts of the East, with a more significant discharge of cold air to follow from the Plains to the East."
Pastelok added that the cold will be interrupted by brief warmups, unlike the prolonged chill of late January and February. Additional cold waves could follow during the first part of April if the polar vortex weakens again.
Through decades of research, it was discovered that sudden warming in the stratosphere (SSW event) is what tends to trigger polar vortex weakening, shifting or splitting days later.
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