Autumn is just beginning, but it’s never too early to think about winter in the northern hemisphere.
It is expected that the La Niña phenomenon will develop before the season and influence temperatures, precipitation, and, by extension, even the amount of snow in the United States this season.
La Niña is a natural climate phenomenon that influences global weather, marked by cooler-than-average ocean temperatures in the equatorial Pacific. The effects on the climate are most pronounced during the winter months in the Northern Hemisphere and have a much weaker influence in the summer.
Last winter was one of the warmest on record and was dominated by La Niña’s cousin, El Niño, which brought warmer-than-average ocean temperatures and caused prolonged heat to prevent heavy snow from developing in the Northeast and Midwest of the country.
La Niña has not yet arrived, but there is a 60% chance it will emerge by November, according to the Climate Prediction Center. When it arrives, it will stay throughout the winter and is likely to persist at least until early spring next year.
Although it is still unclear how strong La Niña will be, current forecasts believe it will be a weaker phenomenon.
The strength of La Niña matters— the stronger it is, the more “consistent” impact it can have on the weather.
So, in other words, what will winter be like?
No two La Niña winters are the same, but they share common temperature and precipitation trends.
This is due to the behavior of the jet streams, which often shift north during a La Niña winter. This typically shifts stormy weather from the South to parts of the northern U.S.
This is almost exactly what the latest winter forecast from the Climate Prediction Center shows for December to February.
The entire northern U.S. is expected to end up wetter than normal this winter, especially the Pacific Northwest, the Midwest, and parts of the interior Northeast. The wet weather will be crucial in combating the ongoing drought in the Midwest.
It’s a complete turnaround from last winter’s pattern, which favored a wetter South and a drier North.
More precipitation than normal does not guarantee that there will be more snow. Temperatures still need to be cold enough for snow to fall.
Weaker La Niña phenomena tend to generate more snow in the Northeast, while snow becomes more limited during stronger La Niñas because higher temperatures generally rise more on the East Coast.
The season is expected to be warmer than normal across almost the entire southern half of the U.S. and much of the East. This could mean that some winter storms in parts of the East will end up wetter, rather than snowier.
Source: CNN