‘Loop’ in jet stream keeps rain away from Bay Area — for now

Meanwhile, storm system could drench SoCal as flash floods possible

“Fire danger in Southern California is really going to drop a bunch if we see an inch of rain in lots of areas. It’s a huge deal down there.” — Jan Null, a meteorologist with Golden Gate Weather Services in Saratoga

Winter is coming. No, really — at least in some parts of California.

But the Bay Area will have to wait another week or more.

In an unusual reversal, Northern California is expected to remain dry, facing high fire danger and PG&E power outages through Thursday, while a storm system is forecast to bring the first significant rain of the season to Southern California during the same time, delivering up to 1 inch in Los Angeles and Orange County and 2 inches in San Diego.

As Bay Area residents looked enviously south, the National Weather Service issued a flash flood watch for today for Riverside, San Bernardino and San Diego counties, with gale warnings off the Southern California coast.

“There’s a loop in the jet stream that is zigzagging around the Bay Area,” said Jan Null, a meteorologist with Golden Gate Weather Services in Saratoga. “It’s picking up moisture off the Southern California coast. But it’s not bringing a lot of moisture with it for Northern California. We are being left out. All

we are getting is the wind.”

That same low-pressure system, which is pulling remnants of Tropical Storm Raymond from Baja California, is forecast to bring snow across the Sierra this week, from Lake Tahoe to the Tehachapis.

The weather service issued a winter storm warning for the Central and Southern Sierra from 10 p.m. Tuesday to 4 p.m. Thursday.

Snow accumulations of 3 to 6 inches are expected from 6,000 to 7,000 feet, the weather service said, with 6 to 12 inches above 7,000 feet.

“I’m excited. I’m actually in Truckee right now,” said Michael Reitzell, president of Ski California, a trade association representing 32 ski resorts in California and Nevada. “When I woke up it was ice cold. It’s starting to feel like winter.”

Three major Tahoearea resorts — Squaw Valley, Alpine Meadows and

Mount Rose — opened last week using machinemade snow. Several others are expected to open this weekend.

Meanwhile, officials at Yosemite National Park, concerned about icy road conditions, announced plans to temporarily close the Tioga and Glacier Point roads through the park’s high country, starting at 3 p.m. Tuesday. The road closures may last for several days or longer, the park said.

“We are taking some

preventative measures,” said Jamie Richards, a Yosemite spokeswoman. “All motorists should be prepared for winter driving conditions. People should have tire chains in their vehicles.”

Similarly, Caltrans scheduled road closures for two of the main routes over the Sierra starting at 6 p.m. Tuesday: State Route 4 at Ebbetts Pass in Alpine County and State Route 108 at Sonora Pass in Tuolumne County.

Forecasters say the Bay Area and other parts of Northern California may join in the precipitation a week from now.

Computer models are showing that a storm system could bring rain the morning of Nov. 27 through Thanksgiving Day. As with all forecasts, the closer the date, the more accurate the forecast.

“There could be a system coming down that could bring us rain,” said Anna Schneider, a meteorologist with the weather service in Monterey. “It’s still pretty far out to say with a lot of confidence. We’ll know more by the weekend. It’s

definitely something to be hopeful about, but it’s still a week out.”

The Bay Area is in the middle of one of the driest starts to its winter rainy season in recorded history.

In downtown San Francisco, this year ranks as the eighth-driest Oct. 1 to Nov. 18 period for the past 170 years, back to 1850 when modern weather records started being kept in the Bay Area.

This year, downtown San Francisco has so far received only 0.03 of an inch of rain, or 1% of its historical average of 2.83 inches by this time of year.

“It’s not that unusual to have a relatively dry October, but to have a bone-dry October with a bone-dry November is much more dramatically unusual,” said Daniel Swain, a climate scientist at UCLA. “As we move forward another week without significant rainfall, that puts us on track for one of the driest if not the driest autumns in Northern California.”

The good news is that most major reservoirs across the state are still at or above historical averages, thanks to a wet winter last year and in 2017.

While Northern California worked to avoid major new wildfires under the red flag warning called by the weather service for 4 a.m. today through 7 a.m. Thursday, with low humidity and dry offshore winds, Southern California will see those fears eased.

“Fire danger in Southern California is really going to drop a bunch if we see an inch of rain in lots of areas,” said Null. “It’s a huge deal down there.”

For Northern California, on the other hand, it’s a race against the clock.

“A little over a week from now there may be a chance for some precipitation,” Swain said. “It does look like a higher chance for at least some rainfall that will finally mitigate the wildfire risk if and when it occurs. But the problem is we have two significant wind events to get through — one now and one early next week.”