Record-Early Polar Vortex Disruption: Will It Bring a Cold Outbreak? Plus Next Week's Heavy Snow Outlook

High above the Arctic, the polar vortex is breaking down earlier in the season than scientists have ever recorded. That has many Americans wondering whether a blast of Arctic air is on the way. For now, forecasters’ answer is not yet, and maybe not at all this month. The only clear winter threat on NOAA’s near-term hazards map is heavy mountain snow in the West.

What is happening to the polar vortex?

The polar vortex is a ring of strong westerly winds about 10 to 30 miles above the Earth that usually keeps the coldest air locked up near the North Pole. When strong atmospheric waves disturb it, the stratosphere can warm suddenly and the winds can weaken, reverse or split. Scientists call this a sudden stratospheric warming (SSW).

According to Smithsonian Magazine, only two other SSWs have been documented in November since reliable records began in 1958. The earliest previous disruption happened on Nov. 28, 1968. On Thursday, the FOX Forecast Center said a major disruption could come within 24 hours or about a week later. In its November outlook, NOAA’s Climate Prediction Center (CPC) called a November SSW “very rare” and said its effects can show up for up to two months.

Will it cause a cold outbreak in the U.S.?

Not right away, according to current forecasts.

• “So far, models continue to show no major cold air outbreaks in the future,” the FOX Forecast Center said.
• Changes in the stratosphere usually take several weeks to work down and affect the jet stream. FOX Weather said any North American impacts are more likely in late November or December.
• For now, models show the coldest air pooling over Eastern Europe and Siberia, while North America stays much warmer than average.

The big counterweight is El Niño. The CPC said the ongoing El Niño “remains the dominant” influence on its November forecast. Its updated outlook favors above-normal temperatures across the northern U.S. and along both coasts. FOX Weather said a stronger Pacific jet stream should carry mild air across the country starting next week.

There is still real uncertainty. The CPC noted that a disrupted vortex often leads to a negative Arctic Oscillation, which can favor cold in the East. That pattern would compete with El Niño’s warmth. Smithsonian pointed to the 2021 disruption that helped bring the deadly Great Texas Freeze. It also said experts aren’t sure how this year’s event will interact with a “super” El Niño. One AccuWeather meteorologist said El Niño will still be “the primary driver” this winter.

The heavy snow map: who is at risk next week?

The CPC’s week-two hazards outlook, often shared as a heavy snow map, shows a moderate risk of heavy snow from Friday, Nov. 13, through Sunday, Nov. 15. According to Autoblog’s summary of the map, that risk covers:

CPC forecaster Thomas Collow said the chances of three-day snow totals above six inches have declined since the Nov. 4 outlook, according to Autoblog. That means the risk could be lowered again.

What it means for travel

The snow zone includes Interstate 80 over Donner Summit and U.S. 50 over Echo Summit. Drivers crossing the Sierra on those dates should expect possible chain controls near the passes, even if lower elevations only get rain. Check Caltrans QuickMap or ODOT TripCheck before you go.

A late first freeze in the East

Most of the Lower 48 leans warm. According to Autoblog’s summary of the CPC map, the main exception is near-freezing overnight lows in parts of the Middle Mississippi Valley, Ohio Valley and Mid-Atlantic. For many places there, that would be the first freeze of the season, arriving two to three weeks later than usual.

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