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The upcoming winter in the United States is set to be more unpredictable compared to last year, according to the National Oceanic and Atmospheric Administration (NOAA). Released on Thursday, NOAA's latest forecast outlines a season influenced by a weak La Niña climate pattern, suggesting colder and snowier conditions in the North, potential dryness in the South, and relative warmth in the Southeast.

La Niña, characterized by cooler-than-normal water in the equatorial Pacific Ocean, last occurred in the 2022-2023 winter season. Although the current La Niña pattern has been slow to develop, there remains a 75% chance of its establishment between December and February. This shift comes after last winter's robust El Niño phase, with NOAA and other agencies expecting the La Niña to bring typical seasonal weather variations.

One hallmark of La Niña winters is a semi-permanent dip in the jet stream over Canada and the northwest United States, along with higher pressure off the Southeast coast. This often results in warmer conditions in the East and cooler conditions in the West. Additionally, an active inland storm track is common, which can lead to storms that are less moisture-laden compared to El Niño storms originating farther south.

NOAA's outlook also hints at a higher risk of severe weather in the Southeast and increased variability in weather patterns this winter. Warmer-than-normal temperatures are expected from the southern United States up to the East Coast, while the Pacific Northwest to the northern Plains are at higher risk for cooler-than-normal conditions. Northern Alaska is predicted to experience warmer-than-normal weather, contrasting with cooler conditions expected in the southern part of the state.

Precipitation forecasts are consistent with typical La Niña winters. The southern United States is likely to see below-average precipitation, whereas the Northwest U.S., northern Rockies, and Great Lakes may receive above-average precipitation. This could benefit drought-affected regions in the Midwest and central Appalachians by providing much-needed moisture.

The forecast for California suggests a potentially dry winter, contrasting with the wet conditions observed during the last La Niña two years ago. For the Northeast, La Niña winters generally bring mixed storms that start with snow and transition to other forms of precipitation, particularly favoring an inland track until reaching New England.

AccuWeather's forecast, also released recently, echoes NOAA's expectations, predicting above-average snowfall for northern New England, the Great Lakes, and along the U.S.-Canada border. In contrast, the Midwest, Mid-Atlantic, and central California through the central Plains may experience below-average snowfall.

Weak La Niña events, like the one anticipated, can allow other, less-predictable factors to influence winter weather more significantly. Other climatic phenomena, such as the Arctic Oscillation and the Madden-Julian Oscillation, along with ongoing climate change and record-warm ocean temperatures, contribute additional layers of complexity to the forecast.

Researchers like Judah Cohen, a meteorologist at Atmospheric and Environmental Research, also consider factors such as autumn snow coverage in Siberia, which can affect U.S. winter conditions. This October has seen significant snow coverage in Siberia, the most since 2014, although its impact on the upcoming winter remains to be seen.

Emily Becker, an atmospheric scientist at the University of Miami, highlights the evolving nature of La Niña amid climate change. "The expected La Niña is occurring in the context of climate change, and the global oceans are much, much warmer than in our recorded history," she noted, emphasizing the uncertainties surrounding La Niña's development and its potential impacts on winter weather.