Powerful Santa Ana winds and drought conditions have fueled the wildfires...

Powerful Santa Ana winds and drought conditions have fueled the wildfires in Greater Los Angeles, including the Palisades Fire, above last week after it began. Credit: Getty Images/Apu Gomes

As firefighters continue to battle the Greater Los Angeles wildfires that have raged for a week, leading to 24 deaths as of Monday and estimated damage in billions of dollars, investigators are still searching for the cause.

Newsday meteorologist Rich Von Ohlen described a "perfect 1, 2, 3 setup" of factors that sparked a disaster that California Gov. Gavin Newsom said could become the nation’s costliest ever.

A combination of drought, atmospheric conditions and land management issues all came together on Jan. 7 to create a "perfect storm" of variables, driven by seasonal Santa Ana winds ripping through Southern California mountain passes, fanning the flames of what have been extraordinarily destructive wildfires that have leveled entire neighborhoods.

What are the Santa Ana winds and how do they factor into the wildfires?

Von Ohlen likened them to "a snowball rolling down a mountain slope."

Known as "devil winds" or "katabatic winds," Greek for "flowing downhill," Santa Ana winds form from cool and dry high-pressure air mass areas in the so-called Great Basin of Central California. The winds are blocked by the Rocky Mountains to the east, and then funnel their way through the Sierra Nevada range to the west.

Why are they so strong?

They become compressed as they move through the funnel, the way air is compressed in a jet engine, to create what on the East Coast would be hurricane-force winds. Mild Santa Anas gust between 30 and 60 mph, according to the National Weather Service. Strong ones? Up to 100 mph as they form in the mountains.

Does climate change play a role? 

Global warming could play a role.

"A generalization is that there has been an increase in the average temperature the past 20, 30 years in Los Angeles," Von Ohlen said, "so there's definitely been a general warming pattern that comes into play — just as it has in many parts of the country."

Smoke from the Palisades wildfire as seen from Venice Beach in Los...

Smoke from the Palisades wildfire as seen from Venice Beach in Los Angeles. Credit: AP/Jae C. Hong

In fact, of the 10 driest years in LA area history, the National Weather Service said six were recorded in the past 20 years — four within the past decade.

Santa Ana winds are dry, warm and fast, adding to the mix of ingredients leading up to a wildfire.

Does population density play a role?

Not only do water resources become stressed as population density increases but, Von Ohlen and other experts said, so does evaporation of water in the soil and vegetation. California Public Radio reported this week that the state now sees 78 more annual fire days a year than it did 50 years ago.

All of which, according to the U.S. Drought Monitor, has led to exceedingly dry conditions that Von Ohlen said "creates a tinderbox," and allows the Santa Ana winds to drive the fire from structure to structure. 

Are the Santa Ana winds returning?

On Monday, Los Angeles Fire Department Chief Kristin Crowley said at a news conference that Southern California was "not in the clear" from wildfire threat — especially, amid weather service directives stating the area remains under a red-flag warning through Wednesday.

The weather service warned Santa Ana wind threats will increase again Tuesday and Wednesday, with winds of 25 to 35 mph likely — and gusts as strong as 65 mph or higher expected in some of the hard-hit fire areas.

Does the Northeast ever experience a similar wind pattern?

Though Long Island and downstate New York saw a number of wildfires in late summer and fall, experts say conditions on the East Coast and Long Island differ greatly from those that lead to situations like the roaring California wildfires.

Most of our destructive winds on Long Island, Von Ohlen said, are connected with precipitation — whether in the form of hurricanes, nor'easters, tropical storms or blizzards.

"We rarely get summer winds like that and our dry winds are typically in the 35-45 mph range, so it's just different," he said.

"Most of our destructive winds," he said, "come with water."

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