Strong, damaging Santa Ana winds are expected to bring an extreme wildfire threat to Southern California Monday through Tuesday as the landscape remains dangerously starved and firefighters continue to work to fully contain the wildfires that have killed at least 27 people and thousands of homes were destroyed this month.
While an offshore wind pattern is expected across Los Angeles and Ventura counties Monday through Friday, winds are expected to pose the greatest threat Monday night through Tuesday morning.
There is a possibility that the winds will be similar in strength to the intense gusts that reached speeds of over 90 miles per hour and fueled the devastating wildfires in Altadena and Pacific Palisades.
The big difference in these winds, however, is that they are expected to affect different locations because they will blow with a stronger northeast-to-east tilt than the Jan. 7 event, which had a north-northeast tilt, Rose said Schoenfeld, a meteorologist with the National Weather Service office in Oxnard, California.
Areas likely to experience the strongest gusts include the San Fernando and Santa Clarita valleys, the mountains and foothills of Los Angeles County and much of Ventura County.
Fallen trees, power outages and dangerous ocean conditions are also likely due to the windy conditions.
The ongoing offshore pattern will suck any remaining moisture from vegetation that is already dangerously dry as rain has been “historically rare” in Southwest California, the weather service said.
Relative humidity is expected to drop, especially on Tuesday, reaching single digits in some cases. The winds, along with dry fuels and bone-dry air, would “lead to rapid fire growth locally in new fires,” Ms. Schoenfeld said.
Southern California is ready to burn. Major storms have drenched the landscape over the past two winters, allowing vegetation to thrive. But since spring there has been little rainfall in the region, grasses and bushes have withered and are flammable.
The weather gauge in downtown Los Angeles, a good indicator of precipitation in the county, has recorded just 0.29 inches of rain since May 1. This would be on track to equal the lowest rainfall ever recorded between May and January, with records dating back to 1877.
According to Brian Newman, who analyzes wildfire behavior for Cal Fire, at least five centimeters of rain is needed to significantly reduce the risk of fires. As for expected weather conditions next week, he said: “Hopefully we won't get any new ignitions, any new fire outbreaks – at all.”
Santa Anas are those drying winds that often occur in winter and blow from Nevada and Utah into southwestern California. Using dry desert air, they push themselves over the mountains in the Transverse Ranges, accelerating as they move downhill and howl into the canyons and valleys.
The winds are expected to primarily affect northern and western portions of Los Angeles County and much of Ventura County. At its peak, isolated gusts of 72 to 100 km/h are expected along the coast and in valleys, while isolated gusts of up to 130 km/h are possible in the foothills and mountains.
On Tuesday, warm weather with afternoon temperatures in the high 60s to low 70s and low relative humidity in the teens and single digits will increase the high fire danger.
Winds are expected to weaken on Wednesday, but could regain strength Thursday night into Friday before expected to ease again Friday afternoon.
The weather service is warning the community of severe fires through red flag warnings, and the agency has issued an advisory for portions of Los Angeles County and much of Ventura County from 10 a.m. Monday to 10 p.m. Tuesday. A less severe fire weather warning has been issued for 10 p.m. Tuesday through 10 p.m. Thursday.
In the extreme wind event earlier this month, the weather service increased the severity of the warning, calling it a “particularly dangerous situation,” as isolated gusts of up to 100 miles per hour were predicted.
The agency may release another copy for Monday to Tuesday.
There was no rain in Los Angeles in January, but there's finally a chance of some rain at the end of the month – although it looks like it will be lighter.
“This is frankly bad news for the future fire weather season here,” Ms. Schoenfeld said.