As firefighters battled the stubborn Kincade Fire raging in Sonoma County on Thursday, Calfire crews and Northern California residents were bracing for more bad news, this time in the form of wind speeds expected to double between today and Sunday around the San Francisco Bay Area.
With fire danger across already high enough to prompt Pacific Gas & Electric to shut down service to hundreds of thousands of homes and businesses for the second time in two weeks Wednesday, the wind predictions are downright scary:
In San Francisco, high wind speeds of 15 mph on Thursday were expected to reach as high as 27 mph on Sunday, while gusts in Oakland will jump from 14 mph to 29 mph over the weekend; in Napa, wind speeds will rise from 15 mph to 31 mph, according to the National Weather Service.
“We have another round of red-flag warnings coming this weekend,” said NWS meteorologist Steve Anderson. “The winds will peak on Saturday night, with gusts of over 80 mph in higher locations, and those will be some of the highest winds, if not the highest, of the season so far.”
The high winds, known as the “Diablo winds,” are fairly routine for this time of the year in Northern California, Anderson said, but this week’s dangerous gusts are the result of two disparate pressure systems.
“The Diablo winds are coming from the east and blowing toward offshore, which is the opposite of what normally happens,” he said. “You have a high-pressure system building across the Great Basin, which is Nevada, Utah and Arizona. At the time, we have a low-pressure system just offshore and the close proximity of those two pressure centers creates these strong winds.”
“Mother Nature likes to balance things out,” he added. “So when you have a high and a low, the winds will flow toward that low-pressure area.”
Anderson did have some good news: temperatures in the Bay Area will ease a bit from Thursday’s unseasonable highs, with San Francisco’s high today of 95 dropping to 84 on Friday and then to a normal 72 on Saturday. San Jose will see 75 to 80-degree weather over the weekend, which is normal for this time of the year. Still, no rain is in sight for the Bay Area over the next ten days.
The Kincade Fire, which started Wednesday night and by Thursday noon had scorched 10,000 acres, seemed like a sobering precursor to the fire dangers in store for much of Northern and Central California; wind gusts of 76 mph had been recorded overnight in the area northeast of Geyserville where the Kincade started burning. And it’s not just the Bay Area that’s in the danger zone this week: An alert Thursday morning from the National Weather Service, for example, contained a red-flag warning for “elevations above 2,000 feet in interior Mendocino, northern Lake and southern Trinity counties “due to gusty winds and very low humidity.
“The most likely areas to observe critical conditions are across exposed ridge tops where winds will be strongest,” said the NWS.
The weather service issued similar warnings for parts of Sacramento and San Joaquin valleys, saying “daytime minimum relative humidity values will be very low (Thursday) afternoon, dropping into the teens and even single digits. This along with extremely poor overnight recoveries will lead to critical fire weather conditions for the northern Coastal Range and foothills, the Sacramento Valley, portions of the
northern San Joaquin Valley, the Northern Sierra Nevada below 7000 feet and the adjacent foothills.’
In a statement, PG&E said it is “monitoring and preparing for an additional wind event starting Saturday, October 26, which may require further shutoffs. Early forecasts show that this has the potential to be widespread across PG&E’s service area in Northern and Central California with significant winds.”
And Sunday night could see more gusts as well.
