WASHINGTON — La Niña is expected to be back and it may wreck your winter. But that depends on where you live and if you do or don’t like the cold.
NOAA’s Climate Prediction Center has released its winter outlook. This forecast is not a guide for deciding your detailed ski vacation or New Year’s Eve plans, but it may give you an idea of which winter coat you should buy for the season and if you need to stock up on whiskey and coffee.
“It would be quite surprising to see a third very warm winter in a row,” said Mike Halpert, the deputy director of NOAA’s Climate Prediction Center.
He said the forecast shows conditions will be warmer, but he doesn’t think we will see a top 10 record warm winter like we have the past two years.
You can probably leave the long underwear in storage if you live in the South. NOAA says two-thirds of the continental US will likely experience warmer-than-normal conditions.
The East Coast has anywhere from a 33%-40% chance of having an above-average winter. This doesn’t mean a cold snap or two won’t happen, it’s just less likely.
The Northern Plains and Northwest are the only locations the CPC thinks the winter season will be below average. The rest of the continental US has equal chances of experiencing a normal winter — meaning residents there will have equal chances of having above, near or below-normal temperatures.
You may want to get a waterproof jacket this season if you live in the northern Rockies or Midwest. The CPC is forecasting above-average precipitation in these areas, while a stretch from Southern California to the Carolinas is expected to be drier. Northern Florida and south Georgia — regions that have had drought conditions within the past year, but not now — have the greatest probability of drier conditions.
Drought could develop in some areas of the South due to the drier conditions — especially in areas that missed the rainfall associated with the active 2017 hurricane season.
The winter pattern that is setting up looks to favor storm tracks across the northern tier of the country. This pattern makes it less likely to have Mid-Atlantic and New England coastal storms that develop in the Gulf of Mexico and track up the East Coast.
La Niña is to blame
We are currently in a La Niña watch, according to the CPC’s October discussion. Forecasters give about a 55%-65% chance during the fall and winter that La Niña will fully form.
The effects of El Niño and La Niña are much more noticeable during the winter months across the US. If La Niña forms, this will have a direct impact on the weather this winter.
“If La Nina conditions develop, we predict it will be weak and potentially short-lived, but it could still shape the character of the upcoming winter,” said Halpert.
During a typical La Niña winter, the Northwest and Midwest are typically colder and wetter, while the Southwest to Southeast remains drier than average.
This all happens because the Pacific jet stream meanders higher into Alaska and Canada, helping to keep some of the dips in the jet stream farther north across the Eastern US.
It doesn’t mean that the Southeast will escape winter weather altogether — the chances are just lower, and the average temperature is likely to be above average.
If La Niña does not form as expected, the updated winter outlook issued in mid-November will look different.
Just how accurate is this forecast?
If we look at last year’s winter outlook, most of the US would likely give forecasters a B+ rating on their 2016-2017 temperature outlook.
A year ago, they predicted an outlook very similar to this year’s forecast: warm across the South and cooler across the Northern Plains. They were right about above-average temperatures across the South. However, the jet stream set up a little bit differently than expected and the below-average temperatures expected in the Northern Plains occurred farther west into the Northwestern US.
So, in the big picture, they were close, but if you live in Seattle, you might have had a few choice words to say about last year’s snowy winter and the big fluffy jacket you didn’t buy.
Then there was the precipitation outlook last year. If we stay with the grade-school analogy, forecasters still passed, but their predictions were just slightly better than flipping a coin.
We again turn our attention to the West, where the overall winter forecast was for drier weather, especially in the Southwest. But multiple atmospheric river events in December, January and February of last year wrecked that prediction. Again, overall a passing grade.
Winter is coming
So, look at the big picture: Winter is coming, and we have a bit of an idea as to where.
But there are a lot of dynamics at play here — thermodynamics in fact — and this is not a pinpoint forecast showing you where it will or won’t snow this season. Instead, this is a way to help you mentally prepare yourself for what lies ahead this winter.
Now you know that you might want to buy a raincoat for every day of the week in the Northwest, while in the South you will likely get away with a lighter coat or vest most of the winter.
The coffee and/or whiskey are just a given no matter where you are this winter.