Rain in Valley expected to continue into Friday

A storm blowing into California – not El Niño-inspired, according to climatologists, but a welcome sign nonetheless – is bringing rain to the central San Joaquin Valley and snow to the Sierra.

The showers should end sometime Friday, but the National Weather Service is predicting another colder storm system to hit the Valley on Sunday.

By the time the front reached the Fresno area, about 11 a.m. Thursday, it had lost much of its energy. Fresno received 0.18 of an inch of rain. Madera soaked up 0.07 of an inch, and Hanford gathered 0.04 of an inch.

Snow dropped as low as 6,500 feet in the Sierra north of Kings Canyon. The snow level was around 8,000 feet south of Kings Canyon. Scott Rowe, a meteorologist in the weather service’s Hanford office, said parts of Yosemite National Park will see snow accumulations of up to 2 feet this weekend. Park officials conceded to the forecast and closed Tioga Road for the season.

Earlier, rain and high winds pounded parts of the Bay Area, prompting warnings from the California Highway Patrol and flood advisories along highways. There also were high surf warnings.

Some areas in the Sacramento region received a half-inch of rain, and the Lake Tahoe area was receiving welcome snow. Rain early Thursday contributed to a Fed Ex big rig skidding out of control on Interstate 5, killing the driver of an oncoming pickup and snarling traffic for several hours.

“It has been the biggest storm so far this season,” said Idamis Del Valle, a meteorologist with the weather service in Sacramento.

Rowe said the front brought cooler temperatures: a high Thursday in Fresno of 56, with similar readings through the weekend.

The chance of rain drops dramatically going into Friday, but there still may be scattered showers in Fresno, Rowe said. He predicted a 70 percent chance of showers overnight falling to 60 percent by sunrise on Friday and dropping to 10 percent Friday afternoon.

The storm was courtesy of a system that pushed south from the Pacific Northwest. It’s expected to bring as much as 8 inches of rain along the North Coast, 3 inches to the Bay Area, and feet – not inches – of snow in the Sierra over the next few days, climate experts said.

High-pressure ridge gives way

Better news: While El Niño rains are still weeks away from hitting California, another weather phenomenon that has exacerbated the state’s drought has lifted, allowing heavy storms to target the Pacific Northwest and Northern California.

“Of all the years in which there was a strong El Niño present in the tropical Pacific Ocean, this is the wettest start to any of those years that we’ve observed in the Pacific Northwest, both in Portland and Seattle,” said Daniel Swain, a climate scientist at Stanford University.

Powerful rains have struck Oregon hard over the past three days, according to the National Weather Service, causing some flooding. At least two deaths were attributed to the storm: A woman drowned when she drove into floodwaters, and another was killed after a falling tree crushed her Portland home.

These heavy rains show that the infamous “ridiculously resilient ridge” of high pressure – the weather phenomenon that pushed storms away from California and fueled years of severe drought – has not returned this winter. The absence of the high pressure mass now allows powerful storms to barrel in from the North Pacific.

The forecast comes as a new report by the National Weather Service’s Climate Prediction Center announced this year’s El Niño is still on track to be one of the strongest on record.

“The current El Niño remains strong and is likely to stay strong through the winter,” Mike Halpert, the center’s deputy director, said.

This week’s storms in the Pacific Northwest and California, however, are not directly related to El Niño.

“The key season is really still to come,” Halpert said. “California so far has been somewhat normal in the northern part of the state and drier than average in the south.”

But the heavy rains hitting the Pacific Northwest are a preview of the effects of El Niño expected to sweep through California in the coming winter months, said Swain, the Stanford climate scientist.

“These rains are shifting southward,” Swain said. “The northernmost part of California is now starting to get in on it this week, and it will see some decent rains down to the Bay Area between now and Sunday.”

Bill Patzert, a climatologist with NASA’s Jet Propulsion Laboratory in La Cañada Flintridge, said the recent storm system clearly shows the breakdown of the drought-causing mass of high pressure.

“This is not an El Niño storm yet,” Patzert said. “The El Niño storms will be riding a subtropical jet stream. It’ll look like a convoy coming straight out of the west.”

Patzert offered another explanation for the storm system hitting the Pacific Northwest: “This is an ‘atmospheric river’ that’s hosing Washington and Oregon,” he said. “It originated near the Philippines and moved in a northeasterly direction. It’s a very narrow band of high moisture.”

But the storm impacts still offer a good preview for California, Patzert said. “In some ways, atmospherically, it’ll be different. But the impact that they’re getting is exactly what we’re expecting in January and February in California.”

El Niño is a phenomenon involving a section of the Pacific Ocean west of Peru that warms up, causing alterations in the atmosphere that can cause dramatic changes in weather patterns globally.

But don’t expect it to be a drought-buster, experts said.

“Even though we have this really high confidence in a wet January, February, March, that does not mean that we have high confidence that the drought will be over by the end of winter,” Swain said. “These long-running precipitation deficits are just so big that they’re almost insurmountable in a single year.”

By one calculation, California’s mountainous north would need 2 1/2 times to three times its average precipitation to end this drought. The record is just nearly double the average annual rain and snowfall, which occurred in 1983, during the second-biggest El Niño on record.

Tioga Road closed for winter

Tioga Road closed Thursday, the latest closure of the mountain pass in Yosemite National Park since Dec. 11, 1995.

Tioga Road typically closes each fall and remains closed throughout the winter months and reopens when weather conditions improve in the spring.

Yosemite National Park remains open year-round with snow removal on all other roads within the park. Even with four-wheel drive, all motorists are required to carry tire chains while driving in the park during the winter months.

For updated 24-hour road and weather conditions for Yosemite National Park, call 209-372-0200.

Drivers advised: Get ready for rain, fog

The California Highway Patrol and California Department of Transportation are encouraging motorists to get prepared this holiday season for foggy conditions and reduced visibility throughout the Central Valley.

Drivers should be prepared for any type of weather this season – snow, ice, hail and rainy conditions, and should plan accordingly by keeping their car in good condition and reducing speeds when necessary.

Foggy conditions are already blanketing the Valley floor, and with tule fog the No. 1 cause of weather-related casualties in California, officials are urging safety and precautions.

When visibility is less than 500 feet on major highways between Bakersfield and Modesto, CHP will be implementing their Pace Program to assist in slowing traffic speeds.

Major tips from the agencies suggest never using cruise control during winter conditions, carrying a cellphone, water, blankets and food within your vehicle, lengthening your following distance and driving with your low-beam headlights on.

This story was originally published December 10, 2015 at 11:52 AM with the headline "Rain in Valley expected to continue into Friday."