accuweather is flagging a sharp shift as winter makes a comeback later this week across the Northeast and Midwest after several days of unusual warmth. The setup includes record-challenging highs and warm overnight lows early in the week, followed by a potent storm and trailing cold front expected to begin sweeping the warmth away Tuesday night into Wednesday (ET). The same storm track is expected to bring a dangerous severe weather outbreak in parts of the central and eastern United States, while ice and snow develop along its northern edge.
Record-challenging warmth gives way to a fast, forceful pattern change
Through the first part of this week, temperatures across much of the eastern half of the nation are expected to surge to their highest levels since last autumn. Dozens of locations from the Ohio Valley to the Gulf and Atlantic coasts are expected to challenge or set record daytime highs, as well as record high minimums—meaning unusually warm overnight lows.
In New England, highs in the 60s and 70s are expected to make it feel more like April. Farther south and southwest, widespread highs in the 70s and 80s are expected to resemble typical May conditions. Higher humidity and thunderstorms are also expected to spread northward from the central Plains into the Ohio Valley, the mid-Atlantic, and parts of the South, giving some residents a taste of summer even as the calendar says March.
That warmth is expected to be swept out as a potent storm and its trailing cold front begin pushing through the central states Tuesday night into Wednesday (ET), then into the Southeast later this week.
Storm threats: severe weather, then ice and snow on the northern edge
The storm is expected to unleash a dangerous severe weather outbreak across parts of the central and eastern United States as it tracks eastward. Along the northern edge of the system, a significant ice and snow event is expected to unfold.
A major ice accumulation is possible in parts of southern Canada, with the potential for widespread and long-lasting power outages in heavily populated areas including Montreal, Ottawa, and Quebec City. While the main ice and snow are expected to be in Canada, some ice buildup is also expected in the northern tier of the Northeast—mostly in sparsely populated areas of northern New England and northeastern New York state.
As the cold front reaches the Atlantic Coast later this week, some areas are expected to see daytime highs plunge by 20 to 30 degrees. Highs in the 60s, 70s, and 80s are expected to be replaced by highs in the 40s, 50s, and 60s. The overall temperature swing from early-week highs to late-week lows could reach as much as 60 degrees Fahrenheit in some cases.
Accuweather meteorologist: polar vortex shift is opening the door to Arctic air
accuweather connects this reversal to changes tied to the polar vortex. AccuWeather Lead Long-Range Meteorologist Paul Pastelok said 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.
“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. ”
Quick context: March sun may limit daytime buildup, but travel can still turn slick
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—when surfaces cool and snow falls steadily—travel could become slippery.
What’s next: below-average temperatures favored later in March
The stretch of above-historical-average temperatures that began more than a week ago is expected to continue through Tuesday or Wednesday (ET), before the colder pattern takes hold. Beyond that, the pattern is expected to bring several days of below-average temperatures during the latter part of the second week and into the third week of March—an outlook that accuweather frames as part of an active storm track with repeated shots of colder air.
