California storm dumps record-breaking rain, nearly a foot of snow

The San Francisco Bay Area received “a pretty good soaking” of widespread rain on Saturday after offshore winds finally moved an unusually unpredictable storm system eastward through the region, causing temporary flooding, ponding in the roadways and some scattered lightning.

“It was the wettest day of the week by far,” Rick Canepa, a meteorologist for the National Weather Service’s Bay Area office, said Sunday. “It was a long wait for that [storm] to get here, and it was a pretty complex system, that’s for sure.”

Last week, forecasters were scratching their heads as they tried to determine how the looming storm would play out, noting at the time that the models were trending in “completely different directions” in terms of rainfall intensity. At first, forecasts indicated the possibility of an atmospheric river. 

“But it’s been some years since we’ve had this much struggle with a single weather system,” Canepa said. “It wasn’t just one low [or storm] at times. There were two to three lows within the low that were trying to develop at the same time, causing it to wobble in direction a bit. It’s been a humbling experience, knowing how some of the best computer models in the world were struggling with the structure and complexity of that low-pressure system alone.”

A few hundredths of an inch of rain started to trickle down on Tuesday, and trace amounts continued to fall throughout the week before the washout on Saturday. Canepa said the North Bay got the most rainfall last week – about one to three inches of rain on average with a whopping total of 4.82 inches measured at Venado’s rain gauge in Sonoma County, one of the wettest spots in the region. Meanwhile, Oak Ridge experienced 3.16 inches of rain, while Bodega Bay and Maribel Park saw 2.48 inches and 2.75 inches of rain, respectively. 

The Santa Cruz Mountains all the way up to Daly City and San Bruno were next in line, with 2.29 inches of rain soaking Las Cumbres, 2.25 inches in Loma Prieta, 2.24 inches on Ormsby Road, 1.85 inches in Boulder Creek and 1.76 inches in San Lorenzo Valley.

Just about fourth tenths of an inch to an inch of rain was recorded along the San Francisco Bay shoreline, with 1.27 inches of rain drizzling over downtown San Francisco, 1.08 inches of rain at Mount Diablo and two tenths to nearly an inch of rain across the East Bay. 

“These are healthy rain totals that help greatly reduce the nearer term deficits that we’re just beginning to get,” Canepa said. “We’ve gotten rain before this, but this helps catch us up for the season to date.”

Outside of the region, the Paso Robles airport reported a record-breaking total of 1.74 inches of rain, far surpassing the previous record of 0.51 inches in 1982. Canepa highlighted just how staggering that was, noting the precipitation average for that site is typically 0.87 inches during the entire month of November, and 1.98 inches in December. “This is comparable to a month’s worth of December rainfall, and they recorded that in a single day,” he said.

The storm is currently moving across the Rockies and is expected to impact the East Coast by Tuesday night, Canepa said. Meanwhile, the Bay Area will be left with dry weather and mild daytime temperatures in the mid-to-high 60s and low 70s on Monday and Tuesday. Breezy to gusty winds are expected to develop late Sunday evening in higher elevations at speeds of 20 to 30 mph, which may blow around some debris and cause small branches to break off tree limbs. People are advised to secure any lightweight loose objects outdoors, use caution when operating high-profile vehicles and avoid burning anything outdoors.

“Power outages are possible, but for the time being we’re not anticipating the need for a wind advisory,” Canepa said. “We’ll continue to closely monitor things and see how they develop.” 

Along the California-Nevada border, an early winter storm brought as much as 10 inches of snow to Mt. Rose Ski Tahoe, seven inches to Mammoth Mountain ski base, four inches to Palisades and 0.8 inches to the Central Sierra Snow Lab. Peak wind gusts were as high as 154 miles per hour over the ridgetops of Ward Mountain, 84 mph at Heavenly and 52 mph at Lake Tahoe.

A winter weather advisory remains in effect until 10 p.m. Sunday for the Ruby Mountains and East Humboldt Range as total snow accumulations of three to 10 inches are expected at elevations up to 8,000 feet, and 12 to 18 inches above 8,000 feet, with wind gusts of up to 55 mph. 

“It’s a pretty typical late fall, early winter storm,” said Edan Lindaman, a meteorologist with the weather service’s Reno office. She noted conditions for travel appeared to be promising because the region is expected to trend toward warmer, drier conditions through at least Wednesday. 

“But it is a reminder that we are heading into the winter season,” Lindaman continued. “If you’re planning to travel into the Sierra, Tahoe Basin or Mono Lake, carry your winter travel kit and check the roads before you go.”