SAN FRANCISCO (AP) — A new atmospheric river brought heavy rain, thunderstorms and strong winds to California on Friday, increasing the threat of flooding and snarling traffic.
Flood advisories or warnings have been issued by the National Weather Service for areas around San Francisco Bay, the Central Coast, and the Sacramento and San Joaquin Valleys. Southern California saw less rain overall.
The atmospheric river, known as the “Pineapple Express” because it brought warm subtropical moisture across the Pacific Ocean from under Hawaii, was melting the lower parts of the vast snowpack created in the California mountains by nine atmospheric rivers in early winter and later by storms caused by blasts of arctic air. .
The high-elevation snowpack is so massive it was expected to absorb rain, but snowmelt was expected below 4,000 feet (1,219 meters), forecasters said.
As the storm approached, Gov. Gavin Newsom declared a state of emergency in 21 counties in addition to the 13 previously declared. He asked the president to declare a state of emergency to authorize federal aid.
The California Department of Water Resources has also activated its flood control center.
Evacuation warnings were issued in advance for various foothills and mountain communities prone to flooding and landslides. A small number of Central Coast residents living under a dam near Oceana in San Luis Obispo County have been ordered to evacuate.
Some reservoirs, depleted by three years of drought and filled over the winter by extraordinary rain and snowfall, have had or are planning to release water to control floods.
The releases were scheduled to begin late Friday morning from the state’s second-largest reservoir, Lake Oroville, which collects water from the Feather River in the western Sierra Nevada foothills of the north Sacramento Valley.
The lake level has risen about 178 feet since December 1st. Spouts are designed to allow room for heavy runoff.
Ted Cradock, deputy director of the State Water Project, on Thursday expressed confidence in the 1960s-era Oroville Dam, where thousands of people were forced to evacuate in 2017 after heavy runoff collapsed the main spillway and the emergency spillway began to erode.
“The spillway has been rebuilt to modern standards and we are very confident that it will be able to handle the flows that flow into Lake Oroville,” he said.
Forecasters warned that travel to the mountains could be difficult or impossible during the latest storm. At higher elevations, the storm is forecast to dump up to 8 feet (2.4 meters) of heavy snow over several days.
Snowpack in California’s Sierra Nevada, which provides about a third of the state’s water supplies, is more than 180% of its April 1 average, when it historically peaked.
Another atmospheric river is already in the forecast for the beginning of next week. State climatologist Michael Anderson said a third and possibly a fourth is forming over the Pacific Ocean.
Anderson said California appeared to be “on its way to a fourth year of drought” before the early winter series of storms. “We are in a completely different state now,” he said.
So much snow has fallen in the Sierras and other mountain ranges that residents are still struggling to dig days after previous storms.
In the San Bernardino Mountains east of Los Angeles, the storm reached blizzard status in late February. Roofs collapsed, cars were buried, roads were blocked.
This week, paramedics began delivering prescription drugs to residents still unable to leave their homes, said Fire Capt. Steve Conchaldi, a spokesman for San Bernardino County Emergency Response.
On the far north coast, Humboldt County officials mounted an emergency response to feed a starving animal stranded in the snow.
California fire and U.S. Coast Guard helicopters began dropping hay bales on cattle in remote mountain fields over the weekend, and then the California National Guard was brought in to expand the effort.
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