5-10 Inches of Rain by Wednesday. Flooding, Slides Likely.

Our incredibly stormy February is about to get even wetter, with yet another Atmospheric River headed into the North Bay Area, and very likely bringing flash flooding by Wednesday.  Flash Flood Watches have already been issued for the entire region.

Here is Sunday’s satellite loop, showing lots of moisture streaming in from the west.

A low pressure trough off the west coast will funnel an Atmospheric River of moisture into Sonoma County and the North Bay starting early Monday, and continuing with periods of heavy rain into Wednesday.

Here is the forecast of an Atmospheric River expected to send a fire hose of moist air into the entire Bay Area by late on Tuesday.

On this storm tracker, notice the stream of rain focused on the North Bay and Greater Bay Area from Monday through Wednesday.  That’s the Atmospheric River.  Quite impressive.

You can see the rain really piling up by late Wednesday, with 4-5 inches in the valleys of the North Bay, and 9 inches or more in the wettest locations.

Of course that means flash flooding of creeks and roadways will occur all across the region, and major river flooding is likely, especially after all of the rain that’s fallen across Sonoma County and the North Bay in the past few weeks.

The State River Forecast Center says the Russian River will flood by early Wednesday morning, reaching a peak of 38 feet by around 11PM Wednesday (6 feet over flood stage), before finally dropping below flood stage by Thursday afternoon.  The Napa River is also expected to flood, but is only forecast to reach slightly over flood stage on Tuesday or Wednesday.

Of course, as the storm approaches, this forecast will likely be updated.

And, how about after the 5-9 inches of rain forecast by Wednesday?  Well, after drier weather Thursday and perhaps into Friday, it looks like more storminess may be in store for the weekend, into the week of the 4th.  But, for now at least, it looks like the storms will be cooler with less rain than the big storms coming over the next few days.

Here is the outlook for total rain for Sonoma County and the North Bay from now, through the first full week of March.  This is pretty far out for the weather models, but this is the current best guess.

So, prepare now, as February will definitely be going out like a lion across the North Bay Area!