Days after California was hit by “the most impressive storm in nearly 20 years”, the state – fully saturated in many places – is gearing up this weekend for a new series of atmospheric river events, with flooding, hail, powerful gusts of wind and even funnel clouds possible in places.
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Another round of heavy rain is already falling on the Golden State on Saturday, where an extreme drought fueled by the climate crisis has given way in recent weeks to massive flooding amid a catastrophic sequence of ultra-wet atmospheric rivers – long and narrow regions in the atmosphere that carry moisture over thousands of miles. Recent storms have killed at least 18 people and left tens of thousands at a time without power.
More than 25 million people are again under flood watch across much of California’s central coast, as well as the Sacramento and San Joaquin valleys. Although this weekend’s rainfall count is lower than previous storms, the flood threshold is also much lower as the ground is completely saturated in many areas.
“This atmospheric river is more gradual than some of the other atmospheric rivers that have occurred in recent weeks, which should help limit the extent of flooding potential,” the Weather Prediction Center said. “All that said, pretty much all of California; from the coast and from the Shasta and Sierra Nevada south to the Cross Range have soil moisture percentiles above 95%.
“Parts of the state received 15-20+” rain and >600% of normal precipitation over the past two weeks,” they added.
And unfortunately, the chances of rain don’t end there: another storm will bring further chances of rain and flooding to much of the state from Sunday afternoon through Monday morning before drier conditions set in. finally settle later next week.
“A more intense burst of moisture is expected on Saturday before a stronger Pacific storm system that will move inland throughout the day,” the forecast center said. “A slight, broader risk of excessive precipitation is in place for both the northern California coast, where precipitation will continue from Friday, as well as areas up the Sierra.”
Rain and snow are also expected to spread across the Pacific Northwest and Intermountain West Saturday through Sunday.
Widespread rainfall totals through Monday will range between 2 and 3 inches along the coast and interior valleys, with 4 to 6 inches possible for the San Francisco Bay Area and nearby Santa Cruz and Santa Lucia Mountains. . This will likely lead to some flooding as well as mud, rocks and landslides.
“Rain is a certainty with (a) 100% chance of rain across the region and with deep humidity and heavy rainfall expected, flooding is once again becoming a concern,” the National Weather Service office in San Francisco said.
San Francisco has already recorded one of the 15 wettest winters on record with more than a month to go. If it ends up picking up 4-6 inches of rain over the next three days, the city will easily crack the top five.
A slight risk of excessive precipitation – Level 2 of 4 – alert is in place, mainly due to extremely wet conditions preceding the expected rainfall and leading to increased risk of flooding.
“Forecast soundings showed some instability over the Central Valley behind the front later Saturday afternoon and into the evening with hail likely to accompany stronger storms, and perhaps a few clouds in funnel,” the Sacramento Weather Services office said.
River flooding is also a big concern, especially around the Russian River in Northern California and the Salinas River near Monterey. “Expect additional disruption to mountain travel and recreation over the weekend as periods of heavy snowfall return to the Sierra,” the Reno Weather Service office said.
Very heavy snow is also forecast for the Sierra, with 1-2 feet possible Saturday and another 2-3 feet through Monday. “The heaviest snowfall days will be Saturday and Monday with less intense snow showers in between,” the Reno Weather Service office said.
Strong winds will also accompany this system, with gusts of up to 40-50 mph in the Sacramento Valley and up to 60 mph in the mountains. This could lead to downed trees and staked power lines in now extremely saturated ground.
“The system will pack a decent amount of southerly winds and a high wind watch is in effect for the mountains of San Luis Obispo and Santa Barbara counties – the same strong winds will move into Ventura and LA counties Saturday night” , the weather service office in Los Angeles said.
The good news is that by the end of the week, forecasts call for much drier conditions across California, which will allow the ground to dry out and river levels to drop.
“It’s been a long time since Californians were happy to see an extended forecast of below-average rainfall,” said CNN meteorologist Brandon Miller. “But after the last three weeks, they certainly are.”