As fall unfolds, it’s already time to prepare for the upcoming winter, which promises to be quite different from last year’s El Niño-dominated season. This year, meteorologists predict the arrival of a weak La Niña, which could affect temperatures, precipitation, and snowfall across the United States.
La Niña is a natural climate phenomenon characterized by cooler-than-average ocean temperatures in the equatorial Pacific. Its effects are more pronounced during winter in the Northern Hemisphere, while its summer impact is less significant. This upcoming winter’s La Niña pattern is expected to shape weather trends across the country.
Looking Back: The Impact of Last Year’s Winter
Last year’s winter was the warmest on record for the Lower 48 states, largely due to the influence of El Niño, La Niña’s counterpart, combined with the effects of global warming driven by fossil fuel emissions. The warmth of last winter led to fewer heavy snow events in regions like the Northeast and Midwest, causing a snow drought, with snowfall totals missing by several feet in some areas.
As of now, La Niña hasn’t fully developed, but the Climate Prediction Center (CPC) gives it a 60% chance of materializing by November. Once in place, La Niña is expected to linger throughout the winter and could last into early spring of the following year.
It’s important to note that while La Niña and El Niño play significant roles in shaping seasonal weather patterns, they are not the sole factors at play. However, they tend to have an outsized influence, especially when they are strong. This winter’s La Niña is forecasted to be relatively weak, which could lead to less predictable weather outcomes.
What to Expect: La Niña’s Potential Impact on Winter Weather
No two La Niña winters are exactly alike, but they often share similar temperature and precipitation trends. One of the key ways La Niña affects winter weather is through the jet stream, a fast-flowing river of air in the atmosphere that directs storms. During a La Niña winter, the jet stream tends to shift northward, moving stormy weather away from the southern United States and bringing it to the northern parts.
This is reflected in the CPC’s winter forecast for December through February, which suggests that the northern tier of the U.S. is likely to see wetter-than-normal conditions. This includes areas like the Pacific Northwest, the Midwest, and parts of the interior Northeast. The Midwest, in particular, could benefit from this wet weather, as it would help alleviate ongoing drought conditions.
This winter’s pattern stands in stark contrast to last year’s, which saw wetter conditions in the South and drier weather in the North.
Snow Outlook: Will There Be More Snow This Year?
While an increase in precipitation is likely, more precipitation does not necessarily mean more snow. For snowfall to occur, temperatures both at the surface and in the atmosphere must be cold enough. Weak La Niña events, like the one predicted for this year, often allow for increased snowfall in the Northeast. In contrast, stronger La Niña events tend to limit snowfall due to warmer temperatures creeping up the East Coast.
The CPC’s latest winter temperature outlook isn’t promising for snow enthusiasts in the Northeast. It predicts warmer-than-normal temperatures across much of the southern U.S. and the East, which could result in more rain than snow in some winter storms in the East. Additionally, drier and warmer conditions are forecasted for the South, which could worsen drought conditions throughout the season.
In contrast, parts of the Midwest, the Plains, and the Rockies are expected to see temperatures closer to normal, while cooler-than-normal conditions are forecasted for the Pacific Northwest and parts of the Dakotas. The combination of cooler temperatures and increased precipitation could mean a significant snowpack in the Pacific Northwest, an area where snow is vital for both tourism in the winter and water supply during the warmer months.
California’s Forecast: Wet North, Dry South
La Niña winters typically bring wetter conditions to Northern California. However, the CPC’s forecast suggests that Northern California might see near-normal precipitation levels this season. La Niña has played a role in the extremely wet winters that have affected much of the state in the past, including the December 2022 to February 2023 period.
Southern California, on the other hand, is expected to be drier and warmer than usual, which is typical for La Niña winters. This region is in critical need of rain in the coming months to help shut down wildfire season. Wildfires could continue to be a major threat if the area doesn’t receive enough rainfall, as there is an abundance of dry fire fuels like grasses and brush that could sustain fires.
What’s at Stake This Winter
A weaker La Niña event, like the one currently forecasted, means that other weather and climate factors could interfere with La Niña’s typical patterns. As Emily Becker, an atmospheric scientist at the University of Miami, explained, “A weaker event makes it more likely that other weather and climate phenomena could play the role of spoiler.”
La Niña’s strength is a critical factor in determining how much influence it will have on the weather. Stronger La Niña events tend to create more consistent and predictable weather patterns, while weaker events lead to more variability. As Becker pointed out in the National Oceanic and Atmospheric Administration’s (NOAA) latest La Niña/El Niño blog, a weaker La Niña could result in a wider range of weather outcomes.
The Bottom Line: Expect a Different Winter
In summary, the coming winter will likely be wetter in the northern U.S. and warmer in the South. Snowfall could be more frequent in the Pacific Northwest, the Rockies, and the Northeast, depending on how cold temperatures get. Southern regions, including California, may experience warmer and drier conditions, which could exacerbate wildfire risks if sufficient rain doesn’t arrive early in the season.
While La Niña is expected to be the dominant weather pattern this winter, its weak nature means that other climate forces could also shape the season’s weather. So, while some regions might see more snow than last year, others might experience continued dryness and warmth. As the season progresses, we’ll gain a clearer picture of how La Niña will influence the U.S. this winter, but for now, the focus is on cooler and wetter conditions in the North and warmer, drier weather in the South.