Oct 10, 2023 - News

El Niño may bring extreme weather to West Coast, models suggest

Illustration of overlapping caution icons with exclamation points and severe weather imagery

Illustration: Natalie Peeples/Axios

Climate models are suggesting that El Niño could become a "strong" or even "super'' strong event this winter, potentially bringing a wide range of extreme weather to the West Coast.

Why it matters: Never before have we gone into an El Niño event with global ocean and air temperatures as high as they are now, Daniel Swain, a climate scientist at UCLA, told Axios.

  • "This year has been unbelievably, insanely warm and we are shattering records by margins that are, quite frankly, shocking" he said.

Both climate change and El Niño — a normal and predictable phenomenon — contribute to higher global temperatures and extreme weather events like flooding, heat waves and intense tropical cyclones, writes Axios' Andrew Freedman.

Driving the news: The most recent forecast from NOAA's Climate Prediction Center (CPC) gives a roughly 70% chance for a "strong" El Niño from November through January, NOAA meteorologist Scott Handel told Axios.

  • But the greatest impacts and most extreme weather events will more likely occur between January and March, said Swain.
  • One experimental model developed by the National Science Foundation's National Center for Atmospheric Research (NCAR) suggests that because ocean temperatures in the tropical Pacific are above a certain threshold, we could even see a "super" El Niño.
  • If so, it could become one of the strongest such events on record, comparable to the 1997–1998 El Niño that brought massive flooding to parts of Mexico and dumped 7 inches of rain on Orange County, California, in one day.

Be smart: El Niño predictions are based on a composite of information, including different forecast models, data from the last 15 years and the 30-year climate trend, said Handel. That said, no two El Niños are the same and it's impossible to predict precisely what will happen, he said.

Details: Generally, El Niños bring drier, warmer winter conditions to the Pacific Northwest and wetter conditions to the southern two-thirds of California, said Handel. State officials and climate experts on the West Coast expect varying conditions by state.

  • For Seattle and Western Washington, this could mean less rain and less of our critically important snowpack this winter.
  • In Portland and Northwest Oregon, warm and dry conditions could impact the ski season and aggravate existing drought conditions.
  • San Francisco and southern Oregon are the wild cards, as the region is right at the dividing line between the expected drier conditions of the Northwest and the potentially wetter conditions of the Southwest.
  • San Diego and the rest of Southern California could see much higher than normal levels of precipitation and flooding.

How it works: In the simplest terms, you can think of El Niño as generating atmospheric ripples that spread out from areas of tall tropical thunderstorm clouds that form over a blob of unusually warm water in the Pacific Ocean, said Swain.

  • The reverberation of these ripples, which can cause shifts in the Pacific storm tracks during winter, will depend on the intensity of the blob and where in the ocean it's located, with an east-centered blob having greater impact, he said.

What's next: The Climate Prediction Center will issue the next set of seasonal outlooks on Oct. 19.

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