Warm weather beginning to grip the Midwest and Northeast is expected to last well into November with only brief interruptions of cooler blasts of air. The warm pattern will spurred on by El Niño.
El Niño is the warm phase of routine water temperature fluctuations in the tropical Pacific Ocean and can alter weather patterns around a large part of the globe.
"The weather pattern in much of the Midwest and Northeast will feature more mild days than cool days from the middle of this week into early November," According to AccuWeather Long Range Meteorologist Ben Noll.
The cold pattern and snow from last weekend had roots in north-central Canada. Strong winds aloft, or the jet stream, lined up with surface winds and allowed the cold air to quickly drain a couple thousand miles to the south.
"We have a real El Niño pattern kicking across much of the nation now," Noll said. "The prevailing jet stream over much of the nation will be from the west or southwest in the upcoming weeks."
Warmth will build from the Midwest to the Northeast through Wednesday.
A couple of dips of cool air will follow and graze the Great Lakes and the Northeast through early November, but they will be fast-moving and will pale in comparison to the cold blast from this past weekend.
According to AccuWeather Chief Meteorologist Elliot Abrams, "When compared to this past weekend in the Midwest and Northeast, the weather is not likely to get that cold again until November."
The cool air coming into the Upper Midwest on Thursday and exiting New England on Saturday will originate from southern Canada, rather than the North Pole.
During the warmest days from now into early November, temperatures will climb well into the 50s to the lower 60s in the northern tier states and well into the 70s over the Ohio Valley and much of the mid-Atlantic coast.
During the second half of October, normal temperatures trend downward but generally range from the upper 40s and lower 50s across the northern tier to the middle 60s around the Ohio Valley and much of the mid-Atlantic coast.
"The overall pattern during the next two weeks is also likely to continue through November with most days bringing above-average temperatures across the northern United States," Noll said.
The same pattern can allow storm systems and fronts to tap into the warm air and subtropical moisture in the Southern states.
The upsurge of severe weather during the fall is often called the "secondary severe weather season," and can be enhanced by El Niño conditions.
According to AccuWeather Senior Meteorologist Henry Margusity, "The surge of warm and moist air ahead of advancing cool fronts could bring significant outbreaks of severe weather, especially over the Plains, Midwest and South during the balance of the autumn."
One such severe weather outbreak may begin on the southern and central Plains Thursday into Friday, following locally heavy storms and flash flooding in the Rockies through midweek, Margusity said.