New maps reveal who could see more snow during this year’s super El Niño

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This year’s potentially record-setting El Niño is expected to shape winter weather and snowfall across the US. A new CNN Weather analysis shows how snowfall has changed during El Niño winters, offering clues as to what to expect this season.

El Niño is a natural climate pattern marked by unusually warm water in the central and eastern tropical Pacific Ocean. That extra warmth changes rainfall and atmospheric circulation patterns, with effects on weather that extend far beyond the Pacific.

El Niño’s influence on US weather is strongest in winter , when the jet stream — a fast-moving current of air that helps steer storms — typically shifts south and extends east across North America. That change favors wetter conditions across the United States, while much of the north tends to be drier and experience milder temperatures.

But a wetter winter is not necessarily a snowier one. Snowstorms need sufficiently cold air, so if temperatures are too warm for snow, an increase in precipitation just means more rain.

To get a sense of what El Niño’s impacts can look like , CNN Weather analyzed January-through-March snowfall from 1959 through 2026. The maps below show how past El Niño winters varied from average after controlling for long-term changes in snowfall. They describe historical relationships, rather than predicting this winter’s snowfall.

During past El Niño winters, snowfall was generally above-average across the southern US, stretching from parts of the Southwest and southern Rockies through the southern Plains, southern Appalachians and Mid-Atlantic.

Storms that affect the Mid-Atlantic’s snow chances typically take a track along the spine of the Appalachians or push off the coast and become nor’easters.

These nor’easters are “juiced” by El Niño, according to Jon Gottshalck, chief of the Operational Prediciton Branch of NOAA’s Climate Prediciton Center and lead forecaster for the agency’s winter outlook this year. “They’re very strong, energetic and they’re very wet,” Gottshalck said.

This could bring above-average snowfall to places like Washington, DC, and Baltimore.

Even though the Northeast typically misses out on snow during a strong El Niño winter, all it takes is one massive storm to skew snow totals for the whole season.

Parts of the Pacific Northwest, northern Rockies, Great Lakes and Interior Northeast saw less snow. The shift in storm tracks can leave some northern areas with fewer opportunities for snow, and warmer conditions can also make storms more likely to bring rain.

But remember : This is relative to each location’s average, not a measure of which places get the most snow. So in the South, where snowfall is typically scarce, even a large percentage increase well above average snowfall can still amount to a small total on the ground.

This year’s El Niño is set to be one of the strongest on record. A stronger El Niño increases the likelihood of its typical effects, Gottschalck said.

But it does not necessarily produce a larger increase in rain or snow at a particular location than compared to a weaker event. and Gottschalck noted there are also relatively few strong El Niño events in the historical record to draw firm conclusions from.

An average alone can also be misleading. A few exceptionally snowy winters can pull the totals upward, even if many other winters fall short.

To see where snowier El Niño winters were more common, CNN Weather also examined how often snowfall finished above average during El Niño those years.

Above-average snowfall occurred in more than half of the El Niño winters analyzed across parts of the Southwest, lower Midwest, southern Appalachians and i Interior Northeast. Much of the Pacific Northwest, northern Rockies and parts of the Great Lakes had below-average snowfall more often than not.

And in a moderate-to-strong El Niño, like this year’s super El Niño, those differences grow. Places that typically see above-average snowfall during an El Niño tend to see even more frequent snow during a strong El Niño, while places that typically see less tend to have snow even less frequently.

The wide spread in totals in cities across individual El Niño winters illustrates how El Niño only offers a rough guide to how snowy an individual winter could be.

For December through February, NOAA’s outlook favors warmer-than-average temperatures across much of the northern and eastern US.

The Pacific jet stream will be “flooding North America with Pacific Ocean air,” Gottschalck said. That milder ocean air should make prolonged Arctic outbreaks harder to sustain, although shorter bursts of cold remain possible.

One wild card is how atmospheric circulation patterns over the Arctic and North Atlantic evolve. Changes there can allow cold air to spread into the eastern US and alter the paths of storms, even under a strong El Niño.

A persistent pattern favoring cold could disrupt the expected mild winter across the north, Gottschalck said. But forecasters cannot reliably predict in October when those episodes will occur or how long they will last.

The timing of the cold air will become clearer much closer to individual storms, he said. Even in a generally mild winter, a brief cold spell that coincides with a powerful coastal storm can make a big difference in a season’s snowfall.

During the very strong 2015-16 El Niño, New York City had one of its warmest winters on record according to the National Weather Service. Yet the January 2016 blizzard dropped 27.5 inches in Central Park, setting the city’s single-storm snowfall record.

CNN Meteorologist Mary Gilbert contributed to this story.

马修·乔纳斯/媒体新闻集团/博尔德每日相机报/盖蒂图片社

今年可能打破纪录的厄尔尼诺现象预计将影响美国冬季的天气和降雪量。CNN天气频道的一项最新分析显示了厄尔尼诺现象期间冬季降雪量的变化，并为我们预测本季的降雪情况提供了线索。

厄尔尼诺现象是一种自然气候模式，其特征是太平洋中部和东部热带海域海水异常温暖。这种额外的热量会改变降雨和大气环流模式，其对天气的影响远远超出太平洋地区。

厄尔尼诺现象对美国天气的影响在冬季最为显著，此时，高速气流（一种有助于引导风暴的快速移动气流）通常会南移并向东延伸至北美各地。这种变化使得美国大部分地区更加潮湿，而北部大部分地区则往往更加干燥，气温也更加温和。

但冬季降水增多并不一定意味着降雪增多。暴风雪需要足够冷的空气，所以如果气温过高不适宜下雪，降水量的增加就仅仅意味着雨水增多。

为了了解厄尔尼诺现象的影响，CNN天气频道分析了1959年至2026年1月至3月的降雪量。下图显示了在控制了长期降雪量变化后，过去厄尔尼诺冬季与平均水平的差异。这些地图描述的是历史关系，而非预测今年冬季的降雪量。

在过去的厄尔尼诺冬季，美国南部地区的降雪量普遍高于平均水平，从西南部和南部落基山脉延伸到南部平原、南部阿巴拉契亚山脉和中大西洋地区。

影响大西洋中部地区降雪概率的风暴通常会沿着阿巴拉契亚山脉脊线移动，或者从海岸向外推进，变成东北风暴。

据美国国家海洋和大气管理局（NOAA）气候预测中心业务预测部门负责人、该机构今年冬季展望首席预报员乔恩·戈特沙尔克称，这些东北风暴受到厄尔尼诺现象的“增强”。戈特沙尔克说：“它们非常强劲、能量充沛，而且降雨量非常大。”

这可能会导致华盛顿特区和巴尔的摩等地出现高于平均水平的降雪。

尽管在强厄尔尼诺冬季，东北地区通常会错过降雪，但只需要一场特大暴雪就能改变整个冬季的降雪量。

太平洋西北部部分地区、北部落基山脉、五大湖区和内陆东北部地区降雪量较少。风暴路径的改变可能导致一些北部地区降雪机会减少，而气温升高也可能使风暴带来降雨的可能性增加。

但请记住：这是相对于各地平均降雪量而言的，而不是衡量哪些地方降雪量最大的。因此，在降雪量通常较少的南方，即使降雪量远高于平均水平，百分比增幅也可能很小。

戈特沙尔克表示，今年的厄尔尼诺现象预计将是有记录以来最强的厄尔尼诺现象之一。厄尔尼诺现象越强，其典型影响出现的可能性就越大。

但与较弱的厄尔尼诺事件相比，它并不一定会导致特定地点降雨或降雪量的显著增加。戈特沙尔克指出，历史记录中强厄尔尼诺事件相对较少，因此难以从中得出确切结论。

单凭平均值也可能具有误导性。少数几个降雪量异常大的冬季会拉高总降雪量，即使其他许多冬季的降雪量不足。

为了了解厄尔尼诺现象导致冬季降雪量增加的地区更为常见，CNN 天气频道还调查了厄尔尼诺现象发生年份中降雪量高于平均水平的频率。

在分析的厄尔尼诺冬季中，美国西南部、中西部南部、阿巴拉契亚山脉南部和东北部内陆部分地区，超过一半的年份降雪量高于平均水平。而太平洋西北部大部分地区、落基山脉北部和五大湖区部分地区，降雪量低于平均水平的情况则更为常见。

在像今年这样的中强厄尔尼诺现象中，这些差异会更加明显。通常在厄尔尼诺现象期间降雪量高于平均水平的地区，在强厄尔尼诺现象期间降雪频率会更高；而通常降雪量较低的地区，降雪频率则会更低。

不同城市在厄尔尼诺冬季降雪总量上的巨大差异表明，厄尔尼诺现象只能大致预测某个冬季的降雪量。

美国国家海洋和大气管理局 (NOAA) 预测，12 月至 2 月期间，美国北部和东部大部分地区的气温将高于平均水平。

戈特沙尔克表示，太平洋急流将“把太平洋的冷空气倾泻到北美”。这种较为温和的海洋冷空气应该会使北极寒流持续时间更长，但短时寒潮仍有可能出现。

一个不确定因素是北极和北大西洋上空的大气环流模式如何演变。这些区域的变化可能导致冷空气扩散到美国东部，并改变风暴的路径，即使在强厄尔尼诺现象的影响下也是如此。

戈特沙尔克表示，持续的寒冷天气模式可能会扰乱北方地区预期的暖冬。但预报员在10月份无法准确预测这些寒冷天气何时发生或持续多久。

他表示，冷空气到来的时间要等到临近具体风暴时才能更加明朗。即使在总体温和的冬季，短暂的寒流如果与强烈的沿海风暴同时出现，也会对整个冬季的降雪量产生重大影响。

据美国国家气象局称，在2015-16年强厄尔尼诺现象期间，纽约市经历了有记录以来最温暖的冬季之一。然而，2016年1月的一场暴风雪在中央公园降下了27.5英寸的积雪，创下了该市单次暴风雪降雪量的纪录。

CNN气象学家玛丽·吉尔伯特对本文亦有贡献。