Updated 4:27 p.m.
(AP) — A cold front traveling down to Northern California from the Gulf of Alaska is expected to bring widespread rain to the Sacramento Valley and dump at least a foot of snow in higher elevations of the Sierra Nevada, weeks before the start of summer, officials said Tuesday.
The first and strongest storm will arrive Wednesday afternoon and will continue through Thursday. A second system is expected Saturday, said National Weather Service meteorologist Brendon Rubin-Oster.
"It's a late season storm and a little unusual, but in terms of intensity, it's a pretty strong storm," Rubin-Oster said.
The rare May storms will bring winter-like conditions and could dump more than an inch of rain in some areas of the Sacramento Valley and up to 2 feet of snow in some mountain spots at elevations of about 7,000 feet. Snow could fall at lower mountain elevations on Thursday, forecasters said.
Rubin-Oster says looking back at more than 70 years of Sacramento records, this May could end up as one of the wettest ever.
"In terms of the top-ten rainfalls, all you need is 1.14 inches to be in the top-10 and to be in the top four, you just need over 2 inches," he said. "So, I'd presume if this works out we'd be in the top ten if not better after all of these storms."
A winter storm warning has been issued from Wednesday night through Friday morning for the Southern Sierra Nevada.
Wet, cold weather will close out the week for #NorCal. Widespread precipitation begins tomorrow with moderate mountain snowfall on Thursday. Active weather will continue through the weekend. Keep an eye out for forecast updates! #CAwx pic.twitter.com/H38fYaxtG2— NWS Sacramento (@NWSSacramento) May 14, 2019
A series of winter storms this year drenched California with rain and snow that has left many of its reservoirs almost full, including the newly rebuilt Oroville Dam, which was at 95 percent capacity Tuesday.
But the cold storms are not expected to cause major runoff from the snowpack, which has a very cold, icy crust that has prevented it from melting, said Department of Water Resources spokesman Chris Orrock.
"The colder it is the longer it takes to melt," he said. "We don't expect major increases on releases from our reservoirs."
Orrock said rivers and streams are at a higher level than during the summer but they still have plenty of room and no flooding is expected.
In Butte County, where two years ago about 200,000 people had to evacuate amid fears the Oroville Dam could collapse during heavy rain, Sheriff Kory Honea took to social media Tuesday to reassure residents about the dam's ability to manage inflow from the upcoming storms.
Honea said rumors have been circulating about the safety of the dam and its spillway. In his post , he said he sent staff to monitor the latest spill, visited the dam himself on Friday and spoke to engineers and hydrology experts.
"Based on all that, I don't believe there is a current imminent threat. If I come to believe there is a problem that puts the safety of our community in imminent danger, I will not hesitate to alert people," he wrote.
CapRadio's Randol White contributed to this report.