Super El Niño Set to Upend US Winter

El Niño is strengthening fast and is on track to become a Super El Niño no later than October, forecasters say — with a nearly 70% chance of ending the year as the strongest on record.

The effects land hardest on the United States in winter, when the pattern peaks and its grip on global weather is strongest.

The short version for Americans: a wetter, cooler, stormier southern tier, and a warmer, drier northern tier with less snow than usual.

What El Niño does

El Niño is a natural climate cycle marked by warmer-than-average water along the equator in the Pacific Ocean. Those warm waters shift the atmosphere in ways that ripple through weather patterns worldwide, and largely predictably.

In a typical El Niño winter, the jet stream — the cross-country river of air storms ride along — is pushed south of its normal position into the southern United States, according to the National Oceanic and Atmospheric Administration. That means more storms and wetter, cooler weather across the South, while northern states turn drier and warmer.

For the Northeast, NOAA data shows strong El Niño winters bring less snow on average. For the Southeast and parts of the southern Plains, the cooler and wetter trend sets the table for snow, sleet and freezing rain — how wintry it actually gets depends on how cold it gets.

Severe thunderstorms shift too. El Niño puts Florida at higher risk of them during winter, while other parts of the Gulf Coast run less active than normal, according to Michael Tippett, a climate scientist at Columbia University.

The forecast numbers

The Climate Prediction Center's December-through-February outlooks already carry El Niño's fingerprints.

The highest odds of above-average temperatures stretch across the entire northern tier, from the Pacific Northwest to the Midwest. Warmer-than-normal temperatures are possible across more than half of the Lower 48.

On precipitation, wetter-than-normal conditions are possible for Southern California, the entire southern tier and even the East Coast, with the highest confidence centered on the Southeast. The drier-than-normal areas are confined to the northern tier — the same places forecast to run hot. Hot and dry does not make snow.