"Now is the time to prepare!" says the National Weather Service, as pretty much all of Northern California is under a Flood Watch starting Thursday, with another incoming atmospheric river that promises to drench much of the state.

It looks like we'll be "covering mayhem" again, as they say in the news biz, with an atmospheric river busting through what meteorologists are calling the "storm door" on Thursday and Friday. Flooding is expected once again, and people with property that's known to flood are getting ready for another doozy. Also, probably, mudslides and landslides, with much of the region already quite wet from the past two months.

San Francisco's Department of Public Works is giving out sandbags again — ten per address — between 8 a.m. and 2 p.m. every day this week at its yard at Marin and Kansas streets. Though it seems likely that people who really needed them already have them after January's storms.

The sun and blue sky you're seeing now is the calm before the storm, thanks to the remnants of a high-pressure system that is set to "collapse" by early Thursday, per the Chronicle. The first phase will be high winds starting tomorrow, with gusts of 35 to 45 mph by Thursday afternoon across SF, Marin, and the Peninsula. But some west- and south-facing areas will see higher gusts, and as the Chronicle's Gerry Diaz writes, "This means places like the Sunset and Richmond districts, Pacifica and the Sonoma County coastline could easily see gusts closer to 60 mph."

Late Thursday afternoon into the evening we'll see scattered thunderstorms and possible hail, with the heaviest rain starting Thursday night.

The Flood Watch goes into effect at 1 p.m. Thursday, but it goes all the way through Sunday morning. As NWS meteorologist Roger Gass tells Bay Area News Group, "The flooding may actually occur after all of the rain has fallen and the runoff really begins to push into the system."

"With how saturated the ground is, given the wet weather we’ve had, it’s not going to take much more for more tree limbs and trees to go down, resulting in isolated and scattered power outages," Gass adds. "It’s going to be bit of a mess again."

The National Weather Service's Weather Prediction Center says "Creeks and streams in the western foothills of the Sierra Nevada will be most vulnerable to flooding from rain and snowmelt."

Local officials in the East Bay are trying to tell people to stay off the roads this weekend, but does anyone really heed these warnings? And as CNN reports, residents and businesses in Big Sur are being told to stock up on supplies to last them at least two weeks, given the high probability that Highway 1 will once again become impassible due to a rockslide.

There was already snow this morning in the Tahoe area, and chain controls were in effect in on I-80. More high-elevation snow is on the way later in the week, and on top of the snow that has already landed this season, 2023 is shaping up to be one of the top three or four snowiest years on record — since records began being kept in 1946.

PG&E says it is mobilizing crews to handle power-line damage during the storm, but many people still could lose power for some period of time. During late February's storms, as Bay Area News Group notes, more than 100,000 PG&E customers lost power, and "although service was restored in hours or days for most residents, some isolated communities were in the dark for a week or longer."

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