A cold front is bringing some moderate rain to San Francisco and all of the Bay Area today, but it will pass, there will be a chilly lull, and then comes the bigger storm.

Are you ready for the first real atmospheric river to hit the Bay Area this winter season? I'm not! But it's a-comin', starting early Saturday, and meteorologists are putting it in the "moderate" category.

Some lighter rain is coming ahead of the storm and hitting Thursday afternoon, with the Chronicle's Gerry Diaz predicting that the Outer Sunset and Outer Richmond will see the first of the rains by 2 p.m., along with 25-mph winds. This rainstorm is expected to dissipate by evening, giving way to a chilly night with a low forecast in the upper 40s — last night was chillier, with the low hitting 44 early this morning.

The bigger storm, which ABC 7 is calling a Level 2, arrives Saturday and will bring about two inches of rain to most of the Bay Area. This is great news for the drought but less great news for holiday festivity, which will all be forced indoors amid what's pretty clearly a COVID+flu surge. But then again it's been freezing and no one is hanging out outside anyway.

Minor flooding and possible downed trees are likely between Saturday and Sunday, with gusty winds throughout. And scattered showers will continue through Sunday.

An earlier atmospheric river hit the Pacific Northwest in early November and brought a bit of rain down to us, but we experienced just some later, after-effects as opposed to the full brunt.

As we've explained over the past few years since this term has been used more often by TV weather people, an atmospheric river or "tropical plume" is a column of condensed moisture, often a thousand miles long and dozens or hundreds of miles wide, that brings with it heavy rain and snow in a short amount of time.

The good news: Next week looks free and clear of rain until about Friday, at least as of now. But the nights are going to be CHILL-y, with lows dipping as low as 41 degrees.

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