Environment & Science

Santa Ana winds may increase during El Niño, data suggest

El Nino Rains Overflow River --El Nino storms flood the Russian River in California in March, 1998.
El Nino Rains Overflow River --El Nino storms flood the Russian River in California in March, 1998.
NASA/FEMA

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El Niño rains and Santa Ana winds can both have a huge impact on life in Southern California, and a new analysis suggests they could be correlated.

Researchers at the Scripps Institution of Oceanography found that if El Niños occur when an ocean temperature pattern known as the Pacific Decadal Oscillation is in a warm phase, then Santa Ana winds increase.

Janin Guzman Morales analyzed 65 years of data to reach this conclusion, and it is a timely one.

She says the strong El Niño predicted for this winter is coinciding with a warm Pacific Decadal Oscillation.

"According to my data, I expect to see higher activity of Santa Ana winds."

Likewise, she said her research suggests that La Niña years during a negative Pacific Decadal Oscillation tend to see fewer Santa Ana events.

Still, she said this is preliminary data and while the correlation is strong, it's not clear how the two patterns interact. Guzman Morales and her colleagues plan to study this further in the months to come.

Prior to this analysis, researchers hadn't seen any strong relationship between El Niño years and Santa Ana winds.

Luckily for Californians, these two powerful weather patterns can't team up and strike at the same time, says Mark Jackson of the National Weather Service.

That's because they generate opposite wind patterns with Santa Anas coming over the mountains from the east and El Niño storms blowing in from the Pacific Oceans to the west.

"It’s a yin and a yang, one’s a dry and one’s a wet. They are not occurring at the same time," Jackson noted.

Santa Ana winds occur when a large amount of high pressure air builds up in the area known as the Great Basin, just northeast of Southern California, roughly between the Sierra Nevada and the Rocky Mountains.

The air eventually spills over the mountains and heats up as it rushes west toward the coast.

El Niño rains begin out in the Pacific Ocean and travel east to come ashore and drench the land.

Jackson says during an El Niño winter, the jet stream can shift between rainy stretches and dry Santa Ana events.

He cautioned though, heavy rains aren't expected until later in the year but dry Santa Ana winds can show up as early as October.

That means hot breezes could stoke fires before the moisture arrives to dampen chaparral and other forest fuels.

So even if a wet winter is on the way, we're not in the clear yet, he noted.