Fall is in full swing, but it鈥檚 not too soon to look ahead to winter, especially one that could feel considerably different than last year鈥檚 dominated by El Ni帽o.
A weak La Ni帽a is expected to develop ahead of the season and influence temperatures, precipitation, and by extension, even snow across the United States.
La Ni帽a is a natural climate pattern that influences global weather marked by cooler than average ocean temperatures in the equatorial Pacific. The effects on weather are most pronounced during the winter months in the Northern Hemisphere and have a much weaker influence in the summer.
Last winter was the warmest on record for the Lower 48 because it was dominated by La Ni帽a鈥檚 counterpart El Ni帽o in a world also warming due to fossil fuel pollution.
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The prolonged warmth prevented many heavy聽snow events聽in the Northeast and Midwest and created a winter snow drought measured in feet of missing snow.
La Ni帽a isn鈥檛 here yet, but has a 60% chance of emerging through November, according to the Climate Prediction Center. Once it arrives, it鈥檒l stick around all winter and likely persist into at least early spring of next year.
La Ni帽a or El Ni帽o are never the only factors influencing weather in a given season or location, but emphasis is placed on them because they typically have an outsized effect on winter weather in the U.S. 鈥 especially when they are strong.
While it鈥檚 still unclear just how strong La Ni帽a will get, current forecasts favor a weaker one.
The strength of La Ni帽a matters 鈥 the stronger it is the more of a 鈥渃onsistent鈥 impact it can have on weather, according to Emily Becker, an atmospheric scientist at the University of Miami.
鈥淎 weaker event makes it more likely that other weather and climate phenomena could play the role of spoiler,鈥 Becker wrote in NOAA鈥檚 latest La Ni帽a/El Ni帽o blog.
Earlier forecasts from the Climate Prediction Center show many of the hallmarks of typical La Ni帽a winters. That outlook could be change when the center releases its latest forecast on Thursday based on trends toward a weaker La Ni帽a.
What could this winter look like?
No two La Ni帽a winters are the same, but many have temperature and precipitation trends in common.
This is due to the behavior of the jet stream 鈥 essentially a river of air that storms flow through 鈥 which often shifts north during a La Ni帽a winter. This typically shifts stormy weather out of the South and into parts of the northern U.S.
That鈥檚 almost exactly what the Climate Prediction Center鈥檚 latest winter forecast shows for December through February.
The entire northern tier of the U.S. is expected to end up wetter than normal this winter, especially the Pacific Northwest, Midwest and parts of the interior Northeast. Wet weather will be crucial to combat ongoing dryness and drought in the Midwest.
It鈥檚 a complete flip from last winter鈥檚 pattern, which favored a wetter South and a drier North.
More precipitation than normal doesn鈥檛 guarantee there will be more snow. Temperatures still have to be chilly enough both above and at the surface for snow to fall and stick to the ground.
Weak La Ni帽a events tend to allow for more snow in the Northeast, while snow is more limited during stronger La Ni帽as because warmer temperatures often creep farther up the East Coast.
If this year鈥檚 La Ni帽a ends up rather weak, this outlook could shift. Still, the latest winter temperature forecasts from the center aren鈥檛 ideal for snow lovers in the Northeast.
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 some winter storms in parts of the East end up wetter, rather than snowier. But with drier and warmer than normal conditions expected across the South, drought conditions could worsen throughout the season.
Parts of the Midwest, Plains and Rockies could end up with temperatures closer to normal this winter while cooler than normal conditions are expected from the Pacific Northwest to parts of the Dakotas.
The combination of wetter and cooler than normal conditions could potentially mean more snow for the Pacific Northwest, an area where a significant snowpack is crucial to tourism in the winter and the water supply for the warmer months.
Northern California is typically wetter during a La Ni帽a winter, but the Climate Prediction Center鈥檚 forecast keeps the region near normal this season. La Ni帽a had a hand in the extremely wet winter much of the state endured from December 2022 to February 2023 and during the wet winter before that.
Southern California is expected to be drier and warmer than average 鈥 typical for La Ni帽a. It鈥檚 crucial the region gets a period of soaking rain in the next few months; wet weather is needed to shut down wildfire season. Without enough rain, fires could continue to burn through the overabundance of fire fuels like grasses or brush available this year.