This post originally appeared on KQED's Climate Watch blog.
Gusty winds up and down California have grounded aircraft and left hundreds of thousands without power this week. But so far, we’ve avoided the most feared consequence — major wind-driven wildfires. This is high season for the notorious winds known in the Southland as “Santa Anas,” and research suggests our changing climate may mean that season gets longer.
In Northern California, they’re called “Diablos” but the physics behind these legendary winter winds is essentially the same: air moves from high pressure to low.
“Generally a stationary high pressure system that sits over the Great Basin – Nevada and inland regions,” according to Norm Miller, who’s been modeling these winds on computers at Lawrence Berkeley National Lab for a few years now. “It sits there long enough and sort of links with the low pressure that’s offshore. And they set up a flow system,” Miller told me in a recent interview at the lab.
As the air squeezes through the canyons, it speeds up — 50-60 mile-an-hour winds are not uncommon. And when air is compressed, it gets hotter. Miller found an anecdote from 1859, when a ship recorded winds coming off the central coast at more than 130 degrees Fahrenheit — and this was over the ocean.