A new study reveals Santa Ana wind events are stronger during El Niño years when they’re also combined with warm sea surface temperatures in the North Pacific Ocean, known as positive Pacific Decadal Oscillation (PDO).
Researchers from Scripps Institution of Oceanography looked at 65 years of Santa Ana winds, dating back to 1948. There were 19 years when both climate events were in play, just as they are now, said Janin Guzman-Morales, a Scripps graduate student.
“I see that during years where you have El Niño and positive PDO conditions, you see an increase in the total Santa Ana wind activity,” said Guzman-Morales.
“And when I say Santa Ana wind activity, I mean stronger events,” she said.
Guzman-Morales said wind speeds were approximately 10 percent stronger on average. She expects this year to be no different.
"I would expect high Santa Ana wind activity," she said.
The North Pacific recently shifted from a cool PDO phase, which was in place for most of the past 15 years. A cool phase is linked to wet weather up north and dry conditions in Southern California.
Guzman-Morales said El Niño doesn’t always go hand-in-hand with a warm North Pacific.
“You can have El Niño and a negative PDO, but when you have El Nino and positive PDO is when you have that significant Santa Ana wind.”
Guzman-Morales said warm sea surface temperatures can lead to an increase of low pressure systems over the Pacific Ocean. Santa Ana winds form when there’s a low pressure system off the California coast and a high-pressure system over the Great Basin region. The combination will create a strong difference of pressure gradient that will push air from east to west in order to alleviate that pressure.
Extreme Santa Ana wind events have increased slightly in general over the last six decades, said Guzman-Morales.
In May 2014, winds in San Diego County were clocked at their highest level on record at 101 miles-per-hour near Lake Cuyamaca.
