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Santa Ana winds explained
01:08 - Source: CNN
CNN  — 

A windstorm is forecast to bring strong and possibly damaging winds to the western US, starting this weekend.

Over 30 million people are under wind alerts across portions of California, Nevada and far western Arizona and Utah. These alerts include San Francisco, Sacramento, Las Vegas and Los Angeles.

Forecast wind models “show a high probability of an unusually strong January wind event tonight,” the National Weather Service (NWS) office in San Francisco said Friday morning. Winds across the region could reach 20 to 35 mph, and wind gusts in some areas could reach up to hurricane-force (75 mph).

Strong offshore winds will develop, blowing from the Intermountain West toward the Pacific Coast.

Santa Ana, off-shore winds blow from inland areas toward the ocean.

Locally across different areas of California, these strong offshore wind events are often referred to as “Diablo winds,” “Mono winds,” or “Santa Ana winds.”

This type of offshore wind event is more commonly seen in the fall across the western US, when the the threat of wildfire is the greatest, but the strength of this particular event is unusual in the winter months.

Hurricane force wind gusts

Some of the strongest winds will occur across Southern California in the form of a Santa Ana wind.

“Winds will likely quickly ramp up to near damaging levels across much of Los Angeles and Ventura Counties by this evening,” the NWS office in Los Angeles said.

These same areas saw strong winds of 40 to 60 mph on Thursday when a slightly weaker Santa Ana wind event occurred. The highest wind gust during Thursday’s event was 62 mph at Magic Mountain Truck Trail in Los Angeles County. However, even higher winds are forecast Friday night into Saturday.

High wind warnings are in effect for the mountains across Southern California until 3pm PT (6pm ET) on Saturday. Northeast sustained winds of 25 to 35 mph, with gusts to 65 mph are expected; however, localized wind gusts to 85 mph near and below the coastal slopes of the mountains are possible, according to the NWS office in San Diego.

“Wind gusts of over hurricane force are possible across Southern California as Santa Ana conditions develop,” CNN meteorologist Dave Hennen said.

Strong winds are forecast to peak in strength Friday night into Saturday morning across the Southwest.

The winds are forecast to peak late Friday into Saturday morning where “widespread damaging winds [are] possible along and below the coastal slopes of the mountains for Orange and southwestern San Bernardino Counties,” according to the weather service.

These damaging winds could blow down trees and power lines leading to power outages and travel will be difficult, especially for high profile vehicles.

It’s not just Southern California that will be impacted by this windstorm. Strong offshore winds will also impact the Bay Area and Central Valley where wind advisories have been issued for the lower elevations and high wind warnings are in effect for the mountains.

Sustained winds of 20 to 35 mph are forecast for this area but gusts up to 70 mph are possible.

As these strong winds blow from areas of high elevation to areas of lower elevation the air in turn warms.

And even though high temperatures are forecast to be in the 60s and 70s, “it’s possible that record highs could be tied or broken today with favorable downslope warming late this afternoon,” the NWS in San Francisco said.

Gusty winds are forecast to gradually weaken on Saturday and Sunday before onshore flow returns to the West on Monday.

Minimal fire threat

Strong winds coupled with low humidity values and warmer than normal temperatures typically raise concern for wildfires, especially out West which has been dealing with extensive drought conditions, but there is a glimmer of good news.

“Despite the strong winds and areas of lowered RH [relative hunidity], fuels are not particularly supportive of fire spread due to precipitation over the last month” the Storm Prediction Center said in their fire weather outlook.

While overall this is very good news, it does not mean to drop your guard. Local conditions could lead to a few hours of elevated to near-critical fire conditions on Saturday afternoon, NWS San Diego tweeted.

The fire threat across North and Central California also remains low Friday into Saturday despite the strong winds.

“Luckily, we don’t have fire weather concerns in NorCal due to the fall and early winter rains,” NWS San Francisco said.

The heavy rains across California have eradicated the highest level of drought across the state and have greatly reduced the level 3 out of 4 “extreme drought” from 80% of the state in mid-December to only 1% this past week.

Nonetheless, while the drought has improved in recent weeks, hundreds of fires have still burned across the nation since the start of the year.

So far, the National Interagency Fire Center estimates that there have been 457 fires across the US in 2022, burning a total of 7,080 acres.

Vice President Kamala Harris was traveling to San Bernardino, California on Friday, receiving an aerial briefing and touring the San Bernardino National Forest in an effort to highlight provisions in the administration’s infrastructure bill to combat the nation’s wildfires.

“As climate change increasingly fuels hotter, drier, and longer wildfire seasons, and development continues to expand in the Wildland Urban Interface, the proactive and preventative measures that are taken while fires are not burning become even more essential.” an administration official tells CNN.