STEVE INSKEEP, HOST:
California firefighters have made it clear there's not much they can do when wildfires spread as quickly and relentlessly as they have this week. It's hard to do much more because there is fuel - dry vegetation, buildings - and because of the Santa Ana winds blowing beyond hurricane strength. We're going to discuss them with Ariel Cohen, who is chief meteorologist for the National Weather Service Los Angeles/Oxnard. He's on the line. Welcome to the program, sir.
ARIEL COHEN: Thank you for having me.
INSKEEP: What are Santa Ana winds?
COHEN: Santa Ana winds are a regime of atmospheric flow unique to portions of Southern California, where we have strong high pressure that builds over the Great Basin area. It spreads through the coastal ranges and adjacent foothills of Southern California. And as it enters the constrictions in the mountains and the gaps in the mountains, we end up getting an acceleration of that flow offshore and to the coast. It dries out, warms up and creates a very favorable environment for wildfires to spread rapidly and grow explosively.
INSKEEP: When you say the Great Basin area, we're talking about that giant inland area that's a lot of desert and mountains. It's coming from there, down through the mountain passes, accelerating as it goes. Is that right?
COHEN: Exactly.
INSKEEP: Now, I know this is an eternal part of life in Los Angeles. There's a famous passage from a Raymond Chandler short story in which he writes about, quote, "one of those hot, dry Santa Anas that come down through the mountain passes and curl your hair," which is a passage we've actually read on this program multiple times because we've had multiple stories about Santa Ana winds. Do people just accept them as a part of life if you live around LA?
COHEN: The typical strengths of these winds are on the order of, say, 30-60 miles per hour when they occur a couple times a year. Every once in a while, we get a much stronger Santa Ana wind event like what we had over the past 24-36 hours, in which case we ended up with a widespread, life-threatening and destructive windstorm.
INSKEEP: When we talk about winds of over 80 miles per hour, that is what makes these fires almost impossible to fight, isn't it?
COHEN: Exactly. In fact, we had - local wind gusts measured upwards of 100 miles per hour.
INSKEEP: Is this worse than it has been in the past?
COHEN: We did see a major wind event that impacted Pasadena back in late 2011, in which case we got a large area of destructive winds occur. However, with that event, we did not experience the same very favorable fire weather conditions compared to what we experienced during the last 24-36 hours.
INSKEEP: How do you think about climate change when you think about an episode like this?
COHEN: We've experienced major wildfires before here in Southern California. And we need to be ready at any time of the year. We're not talking about just a fire season. It's a fire year. You know, the last couple of years, we had major rainfall and very little in the way of combined dangerous fire weather conditions. But as soon as the rain turned off and all of the fuels - vegetation, brush - that grew, it all of a sudden dried out and became a very favorable fire weather landscape for any fires that were to consume those fuels and grow to extreme proportions.
INSKEEP: Ariel Cohen of the National Weather Service in Southern California. Thanks so much.
COHEN: Thank you for having me. Transcript provided by NPR, Copyright NPR.
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