At least two wildfires started on Tuesday morning as the worst windstorm in more than a decade continues to blast Southern California. One in Pacific Palisades has burned hundreds of acres. Another is burning in the hills above the Sunset Strip in West Hollywood. One structure was lost, but fire officials say the blaze was mostly contained.
Rich Thompson, a meteorologist with the National Oceanic and Atmospheric Administration (NOAA), says the region is expecting 60-80 mph wind gusts from the north and northeast, and even local gusts up 100 mph. That means a high fire danger, especially as humidity has dropped to single digits, and no rain has fallen in the region for several months.
“So everything is just really, really, very dry. Definitely some very critical life-threatening winds and fire danger,” he says.
Thompson also explains that when winds at 5,000-10,000 feet in the atmosphere align perpendicular to a mountain range, “mountain waves” can result.
“If you can imagine, just like an inverse wave in the ocean, where you have these strong winds that develop with this perpendicular flow, and these winds will surface for an hour to a different location and then just go away. And it's like a really quick-hitting burst of really strong winds that you know can cause some very significant damage.”
He continues, “If you remember the 2011 Pasadena windstorm, that was a mountain wave situation where you just had, for an hour or two, these strong winds just surfaced in the valley floor and caused all sorts of damage. And so you have these mountain waves on top of just this predominant, strong Santa Ana winds that we're getting. So it's definitely just a bad combination.”
That Pasadena windstorm knocked out power for days for nearly half a million people. Thompson says the same potential exists today and tomorrow from the Simi Valley in Ventura County, across the 118 to 210 freeways, to Claremont at the southeast end of the San Gabriel Valley.
He notes that any terrain with canyons and valleys can funnel wind, thus causing fires to spread rapidly.
What about the possible link between climate change and these powerful wind events?
“To prescribe climate change to producing these really strong winds this particular time, you really can't say that as a direct correlation. But the overall antecedent conditions that maybe lead to this … colder air moving into the Great Basin, the dry conditions we've had with no rain … that's where climate change can be said to be contributing, like the fire danger we have for the next couple days, just because we haven't had any rain so far in this winter.”
As for the upcoming forecast: No rain for the next few weeks, and another round of Santa Ana winds will repeat after this event dies down.
What precautions should people take now? “[Expect] downed trees and power lines. So you can do without power for a certain length of time. Also, if you're driving … debris can be blown across freeways, that can cause accidents. … And then just the fire danger itself, if you live in the foothills or the valley areas … that fire threat is very, very significant. So just be prepared to take action if a fire does break out, that you listen to local emergency officials what they're telling you to do, where they're telling you to evacuate, whatever, and just be ready to take the proper actions.”