This winter across the Northern Hemisphere, a prominent meandering of the westerlies is anticipated under the influence of a Super El Niño. While cold air masses are prone to surge into areas around the Gulf of Alaska and the southern United States, warmer-than-normal air is expected to dominate northeastern Canada, Western Europe, and regions near Japan.
1. Westerly Jet Stream Outlook (Atmospheric Circulation Characteristics)
According to the 500 hPa geopotential height and anomaly forecasts averaged from December 2026 to February 2027, the impact of a Super El Niño is projected to be pronounced this winter.
- Cold Air Inflow Zones: The jet stream will dip southward predominantly over the Gulf of Alaska and the southern United States, facilitating cold air outbreaks.
- Warm Air Inflow Zones: The jet stream will track further north than normal over northeastern Canada, Western Europe, and near Japan, favoring the advection of warm air masses.
2. Regional Snowfall Outlook
■ Japan
【Meteorological Factors & Drivers】 The typical winter-type pressure pattern (west-high, east-low) will remain weak, and southward cold air intrusions are expected to be milder than normal. However, troughs of low pressure will influence the region periodically, and the transit frequency of southern coastal low-pressure systems (Nankan lows) is projected to increase. Temporary surges of strong cold air remain possible. In addition, sea surface temperatures around Japan are above average, supplying higher moisture levels than normal.
【Snowfall Trends】
- Sea of Japan Coast (San'in to Tohoku): Below average.
- Hokkaido (Sea of Japan Coast): Near average.
- Hokkaido (Pacific Coast): Near to above average, particularly along the Pacific side.
- Pacific Coast (Tohoku to Western Japan) & Northern Kyushu: Near average.
【Flight Operations Advisory】 In southern Tohoku and Kanto-Koshin, heightened vigilance is required for heavy snowfall associated with the passage of southern coastal low-pressure systems.
■ South Korea
【Meteorological Factors & Drivers】 The winter monsoon pressure pattern is forecast to be weaker than normal, leading to milder cold air outbreaks. Nonetheless, periods of trough activity will periodically impact the peninsula. Elevated sea surface temperatures in the Yellow Sea will supply above-average atmospheric moisture.
【Snowfall Trends】 Near normal overall.
【Flight Operations Advisory】 Temporary surges of strong cold air may bring sudden heavy snow, requiring close attention to abrupt weather deterioration and reduced flight visibility.
■ China
【Snowfall Trends】
- Northeast China & Inland Eastern China: Influenced more frequently by upper troughs; snowfall is likely to be near to above normal.
- Mountainous Areas of Southwest China: Snowfall is likely to be near to below normal.
- Other Regions: Generally near normal.
■ North America (United States & Canada)
【Meteorological Factors & Drivers】 Under the influence of the Super El Niño, the Aleutian Low will shift eastward, favoring development over the Gulf of Alaska.
【Snowfall Trends】
- Alaska, Western Canada & U.S. Pacific Northwest: Warm air advection will dominate; snowfall is expected to be near to below normal.
- United States (South-Central / Southern States): Southward meandering of the jet stream will facilitate cold air intrusions; snowfall is expected to be near to above normal.
- Northeastern U.S. to Eastern Canada: The jet stream will track further north than usual, drawing in warm and humid air masses that bring above-average precipitation. Given the persistently cold temperatures in this region, precipitation is likely to fall mostly as snow, leading to near- to above-normal snowfall.
■ Europe
【Snowfall Trends】
- Western Europe & Western Scandinavia: The jet stream will meander northward, drawing warm air from the south. Consequently, snowfall is likely to be near to below normal, primarily in western Scandinavia.
- Central/Eastern Scandinavia & Eastern Europe: The jet stream will dip southward from the Black Sea toward western Russia; cold air from the north will readily filter into areas to the west of this trough (eastern Scandinavia and Eastern Europe). Thus, snowfall is projected to be near to above normal across central/eastern Scandinavia and Eastern Europe.
■ Russia
【Snowfall Trends】 In the Central Federal District, Southern Federal District, Volga Federal District, Ural Federal District, Northern Siberian Federal District, and Southern Far Eastern Federal District (around Sakhalin), cold air intrusions and cyclonic moisture will be frequent, with snowfall likely to be near to above normal.
Conversely, in the Eastern Far Eastern Federal District, where cyclonic activity is expected to be below normal, snowfall is likely to be near to below average.
Disclaimer
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