Tropical atmospheric rivers churning to life offshore for Thursday arrival
SAN FRANCISCO -- Heavy snow, hail, rain -- it's become the new normal for Bay Area residents since the calendar changed over to 2023.
But this week's forecast is poised to break the spirit of even the heartiest of local resident. Three days of intermittent showers ushering in a wave of atmospheric rivers.
"Buckle up, it's going to be quite the weather ride," the national weather service said. "A few days ago longer range models had pretty low odds for an atmospheric river impacting California, but recent runs have changed dramatically."
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A robust ridge developing over Alaska will aim the tropic jet stream right at California.
"This jet will take aim at the West Coast Thursday into Friday," weather service forecasters said. "A conveyor belt for moisture from the tropics and that's where the atmospheric river signature comes in."
There is a little good news. This weather system will be much warmer than the ones over the last several weeks. The snow levels will be high, but for the snowbound Sierra the upper elevations will still get hammered.
"In other words, a good soaking rain," the weather service said. "Unlike recent precip systems this will be tropical in nature meaning higher snow levels and warm rain processes. Instead of laying out rainfall totals that will undoubtedly change lets just say several inches of rain will be possible."
The saturated hillsides and weakened trees in the Bay Area will need watching from Thursday through Saturday.
"Given the mostly saturated soils flooding concerns seems reasonable," weather service forecasters warned.
The wave after wave of storms has driven the snowpack in the upper levels of the Sierra to more than 50 feet after another stormy weekend.
Mountain roads were closed again in Northern California as yet another cold storm moved through the state on Sunday, dumping snow in the Sierra Nevada and rain in valleys.
Interstate 80 and several other routes were shut down in the Lake Tahoe area near the Nevada border, where the California Highway Patrol said driving conditions were treacherous amid blizzard conditions.
"Travel is highly discouraged!" the highway patrol office in Truckee said on Twitter.
At least three ski mountains in the Tahoe area — Heavenly, Homewood and Sugar Bowl — were closed Sunday out of caution and for the safety of guests and employees, resort officials said.
A winter storm warning was in effect for mountain areas through early Monday but snow showers were possible throughout the week.
More than 30 inches of new snow fell within 24 hours, the UC Berkeley Central Sierra Snow Lab said Sunday morning on Twitter, forecasting up to 4 feet through Monday and more during the week.
An avalanche warning was issued for the central Sierra until 7 a.m. Monday.
