Thanksgiving Outlook Favors Northern Warmth as Polar Vortex Wobbles

Early outlooks from NOAA and AccuWeather point to warmer-than-normal weather across much of the northern United States in the run-up to Thanksgiving, with less than three weeks to go before the Nov. 26 holiday. The picture for the South and Southeast is far less settled, and an unusually early disruption of the polar vortex could still change the forecast.

The outlooks describe broad temperature and rain patterns over a week or more. They are not Thanksgiving Day forecasts for any particular city, and forecasters say those details will sharpen as the date gets closer, according to Newsweek.

What NOAA and AccuWeather are seeing

NOAA meteorologist Laura Ciasto told Newsweek that the agency’s latest Week 3-4 outlook favors above-normal temperatures across the northern half of the country and in California. She said that warmth fits the usual pattern of the very strong El Niño now under way. El Niño is the warm phase of the El Niño-Southern Oscillation (ENSO), a Pacific Ocean climate cycle that shifts weather patterns around the world.

The South and Southeast are harder to call. Ciasto said the numerical models, the computer simulations forecasters rely on, have not yet agreed on a clear signal for that region during Thanksgiving week.

AccuWeather told Newsweek it expects dry, warm weather in the northern U.S. during the holiday week and some rain in the South. The company also expects some snow at high elevations in the West. NOAA said the National Weather Service does not put out specific snowfall forecasts three to four weeks ahead.

The Old Farmer’s Almanac published its own long-range Thanksgiving forecast the week before, calling for rain and mild temperatures in the Northeast and snow in the Upper Midwest. The almanac uses its own long-range method and is separate from the government and private forecasting services.

A record-early polar vortex disruption

The polar vortex is a large band of cold, fast-moving air that circles the Arctic high in the atmosphere. FOX Weather reported on Friday that the vortex had been disrupted at the earliest point in a calendar year on record. When the vortex is knocked off balance, Arctic air can sometimes spill south into North America. FOX Weather said any cold that follows could take several weeks to arrive and is not guaranteed.

A NOAA spokesperson called possible Sudden Stratospheric Warming “the wildcard” in the outlook. A Sudden Stratospheric Warming is a rapid jump in temperature high above the Arctic that can weaken or split the vortex. The spokesperson said such an event can push Arctic air into the eastern and southeastern U.S., and that the way it interacts with El Niño will matter for temperatures in the East and Southeast.

FOX Weather framed the question in terms of odds: El Niño generally works against widespread snow at Thanksgiving, while the vortex disruption adds uncertainty. Whether the disruption leads to noticeably colder weather in the U.S., and when, is still unclear.

Why it matters for holiday travel

Thanksgiving is one of the busiest travel periods of the year in the U.S., and weather on the roads and at airports can affect millions of people. Last year, AAA projected a record 81.1 million Americans would travel at least 50 miles from home over the holiday period.

The two signals pull in opposite directions. A very strong El Niño tends to keep the northern states mild, while a disturbed polar vortex can open the door to Arctic outbreaks. That tension is why forecasters describe the South and Southeast as the most uncertain part of the map right now.

When forecasts will firm up

More detailed guidance will come in stages. The Climate Prediction Center publishes 6-to-10-day and 8-to-14-day outlooks for temperature and precipitation, and local National Weather Service offices issue the shorter-range forecasts closer to the holiday. NOAA and AccuWeather have not yet released their most detailed Thanksgiving forecasts.

Travelers should check updates from the National Weather Service and follow official warnings and advice from local authorities as the holiday approaches.

Source: Newsweek