SAN RAFAEL (CBS SF) — A swirling low pressure system fueled by sub-tropic moisture dumped some of the heaviest rain of the year on parts of the Bay Area Thursday, triggering an urban and small stream flood advisory for the North Bay.
The storm system came ashore Wednesday on the central coast and spread south into the Los Angeles region and north through San Francisco Bay, fed by a long plume of subtropical moisture called an atmospheric river or a “pineapple express” because of its origins near Hawaii.
The latest storm brought some hefty rain totals over the last 72 hours for certain parts of the Bay Area. Morgan Hill in the South Bay got over 7.5 inches of rain since Monday, even more than the over 5 inches that fell in Ben Lomond and Boulder Creek in the Santa Cruz Mountains.
The North Bay and East Bay also had locations with impressive 72-hour totals. Kentfield in Marin County received 5.12 inches of rain, while Mount Diablo in Contra Costa County got 5.26 inches.
It was a flooded mess at State Route 12 and 121 in the Sonoma County community of Shellville where heavy rain left several inches of standing rain water.
At the height of the storm at least five drivers got stuck after water spilled over from the nearby Sonoma Creek.
Tow trucks arrived to rescue a couple of stranded drivers. While trucks made it through, drivers in smaller vehicles could not navigate the water. A couple said they eventually pushed their cars out of the quickly rising water.
Forecasters said radar early Thursday revealed cells of heavy rain detected offshore. Rainfall rates between 0.25 and 0.50 inches per hour, with locally higher rates are possible in heavier showers through the early morning.
The wet roadways created havoc on Bay Area freeways. Four separate spinouts on Highway 24 as it approached the Caldecott Tunnel early Thursday backed traffic up for several miles.
A tree toppled into the No. 2 lane of northbound state Highway 13 just south of Park Ave., according to the California Highway Patrol.
The CHP said the tree went down just before 6:30 a.m. A solo-vehicle traffic collision was reported in the same area around an hour before the tree went down. It’s not clear if the collision and the tree falling down are connected to each other.
CalTrans crews were dispatched to the scene and quickly removed the tree.
The CHP reported numerous spinouts and minor collision throughout the Bay Area and warned drivers to slow down.
At San Francisco International, 91 flights had been delayed by 8 a.m. with 41 flights being cancelled.
Record rainfall was recorded in five spots including Santa Barbara, Palmdale and Oxnard, where nearly 1.8 inches of rain had fallen by Wednesday evening. That’s compared to the record of 1.3 inches set in 1937.
Nearly 5 inches of rain had fallen in northern San Luis Obispo County, while 2.7 inches fell in Santa Clarita, just north of Los Angeles and 2.6 inches was recorded at one spot in Santa Barbara County.
Authorities kept a close watch on Santa Barbara County, hoping there would not be a repeat of the massive January debris flows from a burn scar that ravaged the community of Montecito and killed 21 people.
Mud and rockslides closed several roads in the region, including Highway 1 at Ragged Point near Big Sur, not far from where the scenic coast route is still blocked by a massive landslide triggered by a storm last year.
After an overnight lull, the storm picked up intensity before dawn on the state’s central coast, where thousands of people have been evacuated because of the threat of debris flows and mudslides from wildfire burn areas.
Forecasters warned that disaster was still very possible.
“We’re very concerned,” said National Weather Service meteorologist Joe Sirard. “We’re hoping this isn’t a cry-wolf scenario where people will pooh-pooh what we’re saying.”
© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.