Winter Temperature Outlook Update | weather.com | Bot To News


  • A generally colder-than-usual winter is expected in the northern tier of the states.
  • Meanwhile, the southern US is expected to have a warmer than average winter.
  • Multiple factors are driving the forecast, including La Niña.

Temperatures in an updated winter outlook have tended to be cooler in the northern tier of the nation, but that stands in stark contrast to the warmer-than-average conditions anticipated in the south.

Areas from northern New England west to the upper Midwest and Pacific Northwest are likely to see below-average temperatures for the three-month winter period of December through February, according to outlooks released Friday by The Weather Company, an IBM business company. , and atmospheric G2.

In particular, the northern half of Washington to parts of Montana, North Dakota, Minnesota, and northern Wisconsin are more likely to experience cooler than average temperatures.

On the opposite side of the spectrum, a broad area from the Southeast to the Southern Plains and Southwest is forecast to have the best chance of above-average temperatures over the next three months overall.

Keep in mind that this outlook is a three-month general trend. Therefore, we are likely to see warmer or colder periods in each respective region of the country compared to what is shown above.

With that in mind, let’s dive into the month-by-month details and continue with some of the factors driving this forecast.

december

In December, the outlook has tended to be cooler in the Midwest, but generally remains the same as before along the East Coast.

Meanwhile, the Southwest and much of the Rocky Mountains are likely to see a warmer-than-usual December. However, the extreme of expected heat compared to average has decreased from previous projections in the interior West, that is, from southern Montana to much of Utah, Colorado, Arizona and New Mexico.

January

The dramatic contrast between a colder-than-average north and above-average temperatures in the south begins to sharpen as we head into the New Year.

Overall, the forecast for January is trending cooler from Washington east into parts of Montana, the Dakotas, much of Minnesota, northern Wisconsin and the Upper Peninsula of Michigan.

The area most favored by warmer than average temperatures has shrunk, but still includes parts of the Southwest to the southern Plains.

february

The last full month of winter is expected to have the most pronounced north-south temperature contrast.

Much of the Southeast could be thinking an early start to spring is on the horizon, as well-above-average temperatures are favored in that region.

Meanwhile, locations from the Northwest to the Northern Plains will need to keep winter coats on hand given the higher chance of colder-than-average conditions.

Questions and answers on winter prospects

What is driving the forecast?

La Niña, the periodic cooling of the waters of the equatorial Pacific Ocean, is at play as one of the drivers of the winter outlook once again this year.

“We continue the remarkable momentum toward a third consecutive La Niña winter, a relatively rare event in our recorded history, with the last three peats occurring between 1998 and 2000,” said Dr. Todd Crawford, Atmospheric G2 Vice President of Meteorology.

The cooling of these waters can have an atmospheric ripple effect that influences weather patterns around the world.

In the US, La Niña generally means a colder-than-average winter in the northern and western parts of the country, and a warmer southern and eastern part.

But there is a potential curve with La Niña this winter. The atmosphere’s response, which is ultimately important to our weather patterns, could be weaker than normally expected in a La Niña winter. Therefore, other factors in the atmosphere could nullify the influence of La Niña and lead to a greater number of changes in weather patterns for weeks at a time.

There are other pieces of the puzzle besides La Niña to consider in the forecast, which brings us to the next question.

What is the role of the polar vortex and the NAO?

If the polar vortex stays strong or weakens at some point in winter, it can definitely affect the forecast. However, this ingredient in the forecast cannot be predicted until winter is underway.

In the winter of 2020-21, the polar vortex weakened, and although La Niña was present, a large cold snap contributed to the coldest February 19 on record in the lower 48 states. -Dollar disaster, with Texas especially affected.

Crawford said there is less than a 50% chance of a sudden stratospheric warming (SSW) event this winter. This warming of the stratosphere in the Arctic region is what normally creates the domino effect that weakens the polar vortex.

Since an SSW is unlikely, it implies that the polar vortex will continue to be stronger this winter, keeping colder air more bottled up in northern latitudes like last winter.

The only wild card for this expectation is the NAO, or the North Atlantic Oscillation.

There are some indications that the NAO could enter its so-called negative phase at times this winter, allowing cooler air to spill over to the south and northeast.

This is because there is a high pressure lock near Greenland when the NAO is in its negative phase, forcing cold air to lock in over the eastern states via a southward dip of the jet stream.

Again, this is a factor that cannot be predicted very far in advance, so we will be monitoring it throughout the winter.

Colder air and a locking pattern of weather often develop when the polar vortex is weak.

Will the huge eruption of the volcano in Tonga last January play a role?

While it’s true that large volcanic eruptions have historically had a temporary cooling effect on Earth’s climate, that’s not the case with the Tonga eruption.

“The eruption of (the volcano) in January probably won’t cool the weather, since it was an underwater volcano that spewed water vapor, rather than particles, into the stratosphere; rather, since water vapor is a gas greenhouse gases, may have a warming impact on the climate for years to come,” Crawford explained.

The bottom line, according to Crawford, is that this eruption is not expected to have a significant influence on the weather this winter.

The Weather Company’s primary journalistic mission is to report on the latest weather news, the environment, and the importance of science in our lives. This story does not necessarily represent the position of our parent company, IBM.



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