{"id":17071,"date":"2011-12-01T19:27:29","date_gmt":"2011-12-02T03:27:29","guid":{"rendered":"http:\/\/blogs.kqed.org\/climatewatch\/?p=17071"},"modified":"2011-12-01T19:27:29","modified_gmt":"2011-12-02T03:27:29","slug":"santa-ana-wind-season-may-be-stretched-by-climate-change","status":"publish","type":"post","link":"https:\/\/ww2.kqed.org\/climatewatch\/2011\/12\/01\/santa-ana-wind-season-may-be-stretched-by-climate-change\/","title":{"rendered":"Santa Ana Wind Season May Be Stretched by Climate Change"},"content":{"rendered":"

Could set the stage for more severe spring wildfires<\/strong><\/p>\n

Hear my companion radio feature<\/a> for <\/em>The California Report.<\/p>\n

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Wind-driven flames threaten a house during the 2009 Jesusita Fire.<\/figcaption><\/figure>\n

Gusty winds up and down California have grounded aircraft and left hundreds of thousands without power this week. But so far, we\u2019ve avoided the most feared consequence — major wind-driven wildfires. This is high season for the notorious winds known in the Southland as \u201cSanta Anas,\u201d and research suggests our changing climate may mean that season gets longer.<\/p>\n

In Northern California, they\u2019re called \u201cDiablos\u201d but the physics behind these legendary winter winds is essentially the same: air moves from high pressure to low.<\/p>\n

“Generally a stationary high pressure system that sits over the Great Basin \u2013 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\u2019s offshore. And they set up a flow system,” Miller told me in a recent interview at the lab.<\/p>\n

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As air moves toward the coast, it speeds up and heats up.<\/figcaption><\/figure>\n

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.<\/p>\n

Normally, the season for Santa Anas would be starting to peak right about now, through December and January, and then start tailing off. But Miller has combined what we know about Santa Anas with established large-scale climate models, and found something interesting. He says his research so far suggests that given the way the Western climate is changing, high season for hot winds could be stretched out, with more Santa Anas overlapping with the dry season.<\/p>\n

“And the danger would be that if we see it spread into the dry season longer, then the likelihood of a fire weather condition — high winds, dry air — which is what Santa Anas are conducive to producing, chances of fire are much greater,” says Miller.<\/p>\n

If you were anywhere near Santa Barbara in 2009, you haven’t forgotten the Jesusita Fire. Before it was contained, flames consumed 80 homes and almost 9,000 acres. The video montage below was captured by news videographer Tim Walton, and is a graphic portrait of a classic wind-driven California fire.<\/p>\n