As the Bay Area absorbs an atmospheric river soaking the region, forecasters say multiple subsequent storm systems will follow closely behind, ringing in the new year with a torrent of wet weather.
“This first one is opening the storm door for us,” said NWS Meteorologist Cindy Palmer.
Residents were put on alert Tuesday after the National Weather Service recorded winds upward of 40 mph throughout the greater Bay Area, and a flood watch was issued based on predictions of as much as four inches of rain in some areas.
The flood watch was accompanied by a flood advisory, which is less severe, for more inland areas. Commuters and roadside crews grappled with minor flooding caused by drainage issues, but no major incidents were reported in the area Tuesday.
The latest storm moved in from Guam and matches the characteristics of a “Pineapple Express,” in which rain and winds spare the area from freezing, keeping temperatures in a moderate range spanning the low 40s and upper 50s.
Palmer said the storm moved in faster than expected, which will result in a brief respite from the rain in the first half of Wednesday before a new storm system arrives in the evening. Steady rain is forecasted for Thursday and Friday, and yet another system is predicted to arrive between Saturday and Sunday.
“We are looking at wet weather continuing on New Year’s Day,” Palmer said. “We have several systems lined up.”
As of 4 p.m. Tuesday, 24-hour precipitation totals included 2.43 inches in Oakland, 1.9 inches in San Francisco, 1.59 inches in Gilroy, 1.58 inches in Redwood City, 1.43 inches in Livermore, 1.23 inches in Concord and .75 inches in San Jose, according to the National Weather Service. Kentfield in Marin County was among the wettest locations in the region, recording 4.71 inches during that period.
Palmer added that because of the consecutive storm systems, the water falling in the Bay Area has a chance to help alleviate water shortages: “At this point in time, we’re looking at good beneficial rain.”
San Jose and the surrounding region, as well as coastal cities in San Mateo and Santa Cruz counties and San Francisco anticipated some flooding, but the most notable flooding involved creeks in Sonoma County. However, those rises in water levels had mostly eased by late Tuesday morning.
“Other flooding we’ve seen has been the CHP reporting at onramps and offramps, anywhere storm drains were clogged,” Palmer said. “Thankfully it’s been minor flooding, nuisance flooding.”
Traffic delays were not widespread in the Tuesday commute, though that was likely influenced by lower overall commute volume typically seen between Christmas and New Year’s Day.
Meanwhile, delays were expected to continue for air travelers trying to leave and arrive in the Bay Area, with thousands of cancellations nationwide, according to flight-tracking website FlightAware. Those cancellation figures were largely influenced by Southwest Airlines; nationally, the carrier had cancelled more than 2,600 flights as of evening, or 65% of its total flights for the day.
It was not clear how much weather issues had contributed to the thousands of Southwest cancellations.
In the Lake Tahoe region, heavy snowfall of between 3 and 10 inches was predicted, but in areas above 7,000 feet, the yield could approach a foot or more. A winter storm warning was in effect through at least late Wednesday morning, and road travel to the area will entail chain controls and possible delays.
The Tahoe Daily Snow report on OpenSnow paralleled Palmer’s rain prediction in the Bay Area, with “strong winds and heavy rain and snow … becoming all snow on the mountains through the day and to lake level by Tuesday night,” with a break Wednesday, followed by storms during the weekend and then next week.
Forecaster Bryan Allegretto, who produces the snow report, said the most recent storm has melted significant amounts of snow at the base of resorts and lakeside areas nestled below 7,000 feet, though the snowpack above 8,000 feet is likely high enough to the rest of the ski season.
Wednesday and part of Thursday will be good for the slopes, he said, but he warned that most of Friday and Saturday will not be viable for a lot of skiers and snowboarders in part due to a strong storm expected to bring winds of up to 100 mph at the peaks.
“You get a nice day Wednesday, an unsettled Thursday, Friday and Saturday being two days of snow turning to rain, then rain back to snow,” Allegretto said.
Saturday evening — when a fireworks show is planned for the area — is expected to be clear, and Allegretto said Sunday should be sunny and ideal for skiing before things turn on Monday. It has made planning for the coming weekend, which marks the end of the holiday season, a challenging prospect.
Travelers to Tahoe “might be thinking, ‘Should we stay an extra day?’” Allegretto said, “but if you stay an extra day, you could be stuck in another storm.”
Staff writer Jason Green contributed to this report.
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