Offshore winds are whipping up wildfires in California….Rising temps combined with fire suppression, increased development in wildland areas are making the West dangerously combustible.
[see my post on the No CA fires here; 2015 study found that a warming climate will likely make these “Santa Ana” offshore winds both more frequent and stronger, fueling potentially increasing destructive offshore wind driven fires by 64% ]
and here on fire tornadoes; [““Just like water flows from higher to lower elevation, winds flow down a pressure gradient as they go from high pressure to low pressure,” said Max Moritz, a wildfire specialist with the UC Cooperative Extension. “When they get concentrated, like through a mountain pass, they will speed up, like a river going through a narrow channel.” ]
The deadly fires that swept through California’s wine country this fall made one of the state’s most destructive fire seasons on record even worse, and the fierce Santa Ana winds now whipping up fast-moving blazes in the hills near Los Angeles are adding the year’s damage. As global temperatures continue to rise, scientists say the risk of extreme fire seasons is rising across the West.Wildfires are hugely complex events, complicated by human activity, including rampant development and decades of fire suppression strategies that left too much dry timber and underbrush for fires to burn.
Add the effects of climate change to the mix, and California’s already fire-prone landscape grows increasingly combustible.
After nearly five years of extreme drought, California finally got a lot of rain over the fall and winter. ….An analysis showed the grasses and scrub were at all time record dry levels before the wine country fires in early October. “Fire literally exploded and raced along the landscape,” the National Weather Service said. “This summer was so hot, that even a well-above-average winter wasn’t enough to prevent the record-dry year from drying out vegetation,” Swain said. “Both sides were important.”
Why do these fires spread so fast?
….the seasonal hot, dry Diablo winds, sweeping down from higher elevations, fanned the flames in the North Bay….The National Weather Service reported that wind gusts hit nearly 79 miles per hour. Wind-driven fires can move quickly, and these leapt hundreds of feet in seconds.The southern part of the state has its own seasonal hot, dry winds, called the Santa Ana, and those helped drive the fires near Los Angeles in December. Research projects that those winds will fan more destructive and larger fires in that region—an increase of about 60 percent by mid-century—while non-wind driven fires will also increase because of hotter, drier summers—by nearly 80 percent in the same timeframe.
Development is also an issue in fire risk. Over the past half century, humans have pushed farther into wildland areas, building more homes, businesses, roads and utility lines. As firefighters protect these areas, fewer wildfires—a natural part of many ecosystems—have been allowed to burn, allowing fire fuel to grow. Roughly 46 million homes are in these wildland-urban interface areas, and more than 5 million are in California.
Will extremes get worse with climate change?
Recent research from the Pacific Northwest National Labs and Utah State University scientists projects that extreme drought and extreme flooding in California will increase 50 percent by the end of the century—potentially triggering the growth of vegetation that quickly becomes fuel as temperatures rise in the summer…..