Los Angeles fires: Why forecasters are so alarmed by new extreme winds

An unprecedented fourth “particularly hazardous conditions” fire weather warning came into effect Tuesday morning and is expected to last until Wednesday.

The National Weather Service reserves the designation for an extreme red flag warning when particularly hazardous fire weather conditions are expected.

Of the three warnings issued this season, destructive wildfires broke out in each: the 19,904-acre Wildfire in Ventura County, which burned more than 240 structures; and the 4,037-acre Franklin Fire in Mali in December. The fire spread quickly, destroying 20 structures; last week's Palisades and Eaton fires are now among the deadliest and most destructive fires in modern California history.

Why are forecasters so worried?

Traditionally, National Weather Service offices rarely use the “particularly hazardous conditions” label because forecasters believe long, strong and violent tornadoes are likely. The National Weather Service office in Oxnard, which covers Los Angeles, Ventura, Santa Barbara and San Luis Obispo counties, adopted the system in 2020 in hopes of providing a warning for the most extreme fire weather conditions.

“Any kind of red flag warning is dangerous. But even within this range of conditions there are gradients, so we wanted a way to communicate the extremes of the extremes. That's where PDS came from,” said Weather Service Weather says scientist Ryan Kittell.

timing

A “particularly hazardous condition” went into effect at 4 a.m. Tuesday and will remain in effect until noon Wednesday, covering large swaths of Los Angeles and Ventura counties.

affected areas

The latest alert covers areas including Camarillo, Fillmore, Northridge, Simi Valley and Thousand Oaks. Traditional red flag warnings — for a combination of strong winds, dry air and vegetation, and the expected severe wildfire behavior if ignition occurs — are in effect throughout the region, including Los Angeles, San Diego, Orange, Riverside, San Bernardino Novo and most of San Bernardino. Ventura County and some mountainous areas of Santa Barbara and San Luis Obispo counties.

forecast

There are already strong winds. Peak wind gusts of 72 mph were detected in the San Gabriel Mountains Tuesday morning.

New fires have the potential to spread quickly. With the Palisade and Eaton fires still burning, Kittle said, “those winds are definitely going to stir up some hot spots and reignite the fires.”

Forecasters warn that winds are likely to weaken or weaken throughout the warning period.

“If you do get a lull, don't expect the event to end or the forecast to be broken,” Kittel said. “Stay alert throughout Wednesday as winds could peak at any time.”

This event will be a more traditional Santa Ana event, with winds blowing from the east and fire spreading westward. That means winds will be concentrated more in Ventura County than last week, with winds typically blowing from the north hitting Los Angeles County hard.

“It's definitely going to be more focused in (specific) areas rather than as broad as what we saw last week,” Kittle said.

power problem

Kittle said localized power outages and downed trees are expected, but to a lesser extent than last week.

winter fire

Alex Tardy, a weather service meteorologist, said this time of year in Southern California typically has “the ground is wet, the grass is green, and there's no fragile vegetation.” “Normally we don't get continuous Santa Ana winds either.”

By his count, the region is set to experience its fourth Santa Ana storm since last week's catastrophic fires.

Extremely dry weather also contributes to extreme fire weather. The most recent significant rain in downtown Los Angeles was on May 5, when 0.13 inches fell. Only 0.16 inches of rain has fallen there since Oct. 1, a drop in the bucket compared to the 5.34 inches of historical average rainfall that should be down at this point in the season.

The last time there was so little rainfall between early May and late December was in 1962, when just 0.14 inches fell in downtown Los Angeles, according to National Weather Service meteorologist Rose Schoenfeld.

“We're certainly very close to an extreme record for winter dryness,” Kittel said.

“In my opinion,” said retired climatologist Bill Patzert, “the past nine months have been among the driest in recorded history going back to 1900. In my career, I have never seen a severe Santa Ana event so overwhelming a normal “rainy season.” “

There haven't been many red flag warnings or fires in the past few years. During the water year ending September 30, 2024, downtown Los Angeles received 22.15 inches of rainfall; last year, it measured 31.07 inches. The average annual rainfall in downtown Los Angeles is 14.25 inches.

Conditions should ease and improve starting Wednesday night. Winds will be blowing from the ocean on Friday and Saturday and humidity will increase, but gusty winds could still be a problem in some areas, such as the Antelope Valley and southwest Santa Barbara County.

But this relief may be short-lived. There are signs that another Santa Ana wind event could occur on Sunday and Monday, with a 30 to 40 percent chance of another red flag warning in Los Angeles and Ventura counties.

Are there any signs of relief?

Kittle said next week's fire weather likely won't be “as intense” as last week's, but even that glimmer of hope is tempered by the complete lack of rain in the near-term forecast.

Currently, Los Angeles does not have a high chance of rainfall through January 25th.