Arctic Blast, Sudden Stratospheric Warming Signals, and a Shifting Jet Stream Could Transform Holiday Weather for Chicago and Michigan

An Unsettled Atmosphere Before the Holiday

Meteorologists across the Midwest are monitoring a developing pattern that could send Arctic air plunging into the central United States around Thanksgiving. In Chicago, IL skies have carried a muted, heavy look as the jet stream begins to buckle over the Pacific Northwest. A resident on the city’s North Side said simply, “You can feel the cold waiting."

The setup includes ridging in the jet stream, a strengthening La Niña influence, a moving thunderstorm pulse known as the Madden-Julian Oscillation, and the possibility of a rare November Sudden Stratospheric Warming event. Together they form the ingredients for a sharp turn toward winter conditions in late November and early December.

Sudden Stratospheric Warming and the Polar Vortex

Sudden Stratospheric Warming, or SSW, occurs when large atmospheric waves, called Rossby waves, climb into the stratosphere. Air then sinks and warms around the polar vortex, weakening the tight circulation that normally keeps Arctic air locked near the North Pole. When that band weakens, cold lobes can slip south.

Judah Cohen of MIT described the phenomenon as “the largest type of disruption that occurs to the polar vortex," noting that the atmosphere is at a “critical juncture." He added that if an SSW develops this November, it would be the first such event observed during the satellite era.

The National Weather Service Climate Prediction Center reported that combined atmospheric influences “may usher in a significant pattern change later in the month and into early December," with much of the West, Northern Plains and Central Plains turning colder.

Chicago Region: Arctic Air and Temperature Swings

The Chicago area could see a blast of Arctic air just before or immediately after Thanksgiving. Meteorologist Kevin Jeanes of NBC 5 noted that this early-season cold will not match the intensity of January or February outbreaks, but temperatures in the 20s remain possible.

Forecasters also cautioned that the unstable pattern may produce abrupt rebounds, meaning rapid temperature swings across northern Illinois. Snowfall chances through the end of November appear low, with early signals showing moderate snow staying south of the Chicago region. But the first week or two of December could bring one or two stronger, snow-producing storms if the jet stream allows.

One resident in Joliet, IL commented on the shifting winds. “The cold is coming in pieces. It hits, then it backs off. It feels unsettled."

Michigan: Bitter Air and Storm Potential

Farther east, Michigan is also facing the potential for a significant holiday shift. An Arctic blast could arrive during Thanksgiving weekend or early December, though forecasters say it is unlikely to match the early November storm that dropped up to 18 inches across parts of the Upper Peninsula.

As of Wednesday, November 19, projections for Michigan’s Thanksgiving call for dry weather, with temperatures between 28 and 36 degrees. Those values could support lake-effect snow, and chances for those bands continue to grow. Meteorologists noted the potential for gusty winds, blowing snow and reduced visibility across the Northern and Central Plains, with some wrap-around lake-effect snow possibly affecting the southern Great Lakes.

A resident near Grand Rapids, MI described the early-season chill. “The wind cut straight across the fields. It felt like winter arriving early."

Jet Stream to Control Early December Snow Tracks

Forecasters across the Midwest emphasized that the storm track will depend entirely on how the jet stream responds to the evolving pattern. La Niña tends to push cold air farther south, while the Madden-Julian Oscillation distributes pulses of tropical convection that shift temperature patterns across the United States.

If the jet stream dips sharply, snowstorms could form closer to the Midwest in early December. If it arcs higher, heavier snow may remain south and west of the Chicago and Michigan regions.

National Holiday Travel Concerns

Across the country, AccuWeather meteorologists warned of major travel disruptions as a storm system targets the western United States and parts of the Midwest with heavy snow and cold rain during the holiday. The Northeast is expected to see mainly rain in the days before Thanksgiving.

On the back side of the system, strong winds are forecast to sweep from the Great Lakes into the Northeast, affecting airports and high-profile vehicles. Meteorologists noted that dangerously high gusts could impact holiday events in New York, NY and Philadelphia, PA, potentially grounding parade balloons.

A traveler passing through Detroit Metropolitan Airport summed up the mood. “Everyone is watching the forecasts. The weather feels ready to turn."