As North America prepares for the winter of 2024/25, meteorologists are turning their attention to the Pacific Ocean when analyzing the snow forecast, where a weak La Niña phenomenon is looming. This climate phenomenon is expected to significantly affect weather patterns across the continent, particularly the distribution of snowfall. According to Severe Weather Europe, the coming winter could bring a mix of snowy and dry conditions depending on the region.
More detailed analyses and graphics can be found on the Severe Weather Europe website.
In short: For the winter of 2024/2025, above-average snowfall is expected in the northwestern United States and western Canada, while below-average snowfall is forecast across much of the southern and eastern United States, including the northeast.
Understanding the role of La Niña
La Niña is characterized by below-average sea surface temperatures in the central and eastern Pacific Ocean. This phase of the El Niño-Southern Oscillation (ENSO) typically alters atmospheric circulation patterns, resulting in a stronger jet stream over North America. As a result, colder air masses are more likely to descend into the northern United States, increasing the likelihood of snowfall in certain areas.
Model predictions: ECMWF vs. UKMO
Two well-known forecast models, the European Centre for Medium-Range Weather Forecasts (ECMWF) and the United Kingdom Met Office (UKMO), offer insights into possible snowfall patterns for the coming winter. Although both models provide valuable predictions, they differ in some important areas.
ECMWF Model Insights
The ECMWF model suggests different snowfall outcomes in North America:
- Western USA and Canada: Above-average snowfall is expected in the northwestern United States and western Canada, especially in January. This is consistent with typical La Niña patterns that often bring increased precipitation in the Pacific Northwest.
- Midwest and Northeast: Surprisingly, the model predicts below-average snowfall for much of the Midwest and Northeast U.S. This is unexpected, as these regions typically receive more snow during La Niña winters.
- Southern USA: In line with La Niña trends, the southern states are likely to experience below-average snowfall and warmer, drier conditions will prevail.
- Canada: Above-average snowfall is expected for most of Canada, except for parts of the south and southeast.
UKMO model forecast
The UKMO model shows a slightly different picture:
- Northwest USA: Like the ECMWF, this model predicts increased snowfall in the northwestern United States, reinforcing expectations of a snowy winter for states such as Washington, Oregon and Idaho.
- Midwest and Great Lakes: The UKMO model predicts above-average snowfall for the Midwestern United States and the Great Lakes region, more consistent with typical La Niña patterns.
- Northeast USA: Both models surprisingly predict less snowfall than usual for the northeastern United States, which is atypical for a La Niña winter.
- Southern Canada: The UKMO model predicts below-average snowfall for southern parts of Canada. The ECMWF, on the other hand, predicts increased snowfall for large parts of the country.
- Ohio River Basin: Uniquely, the UKMO model indicates potentially above-average snowfall in the Ohio River basin, a detail not highlighted in the ECMWF forecast.
Monthly snowfall patterns
Snow forecast patterns are expected to change throughout the winter season:
- November: Both models indicate increased snowfall in the western United States, likely at higher elevations. The UKMO model in particular indicates potentially above-average snowfall in the Ohio River basin.
- December: The ECMWF model shows an improvement in snowfall totals in the North-Central United States and the Upper Midwest. The UKMO model forecasts increased snowfall totals around the Great Lakes and in much of Canada.
- January: This month, the La Niña influence is strongest in both models. The ECMWF forecasts a significant area of above-average snowfall in the western/northwestern US and the Midwest. The UKMO model reinforces this pattern and extends the area of increased snowfall further into the Midwest.
Conclusion and considerations
While these forecasts provide valuable insight, they are based on data from mid-August and do not include predictions for February. As the La Niña event continues to develop, subsequent model runs may provide refined and possibly different forecasts.
Particularly interesting is the discrepancy between the models regarding snowfall in the northeastern United States. Typically, La Niña winters bring more snowfall to this region, but both models are currently predicting below-average snowfall. This unexpected forecast requires close monitoring as the winter season approaches.
For winter sports enthusiasts and the tourism industry, forecasts of increased snowfall in the Western United States and parts of the Midwest could be a sign of a promising season. Conversely, the possibility of reduced snowfall in the Northeastern United States could pose a challenge for ski resorts and winter-dependent businesses in that region.
As the winter months approach, meteorologists will continue to refine their forecasts. The strength and persistence of the La Niña pattern will play a crucial role in determining the actual snowfall distribution in North America.
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