SAN FRANCISCO, Calif. (KRON) — Are you ready for round two? Another atmospheric river with flood-triggering downpours will unleash more destruction across the San Francisco Bay Area this week.

“The heaviest rain is set to fall early Wednesday morning, the result of another atmospheric river that is tapping into a very rich plume of moisture extending far out into the Pacific Ocean. Rain totals with this storm are expected to be similar to our New Year’s weekend storm,” KRON4 Meteorologist Kyla Grogan said.

Grogan said drivers should avoid traveling on the Bay Area’s roadways, if possible, on Wednesday.

The National Weather Service issued a Bay Area-wide Flood Watch beginning late Tuesday night and extending through Thursday afternoon.

Waterlogged areas struggling to recover from New Year’s Eve flooding will be pounded again with several inches of rain. Urban areas could see between 1.5 – 3 inches of new rainfall. Mountain ranges are forecast to see 3– 6 inches of rain.

Homes and businesses located near rivers and low-lying areas are at the highest risk of flooding. Areas within wildfire burn scars face possible mudslides.


“There is particular concern for those living in landslide-prone areas, burn scar areas, and those living close to rivers. The ground is simply unable to absorb all of the water, and instead, it causes flooding. We have very saturated ground, and additional rainfall is only going to exacerbate the dangers that we experienced last weekend. The important message right now is for people to make any preparations they need to on Tuesday ahead of this next storm system,” Grogan said.

The cities of San Carlos and Foster City reported that some of their locations ran out of sandbags on Monday. Here’s where you can get a free sandbag to prepare for the next round of rain.

Forecasters with the National Weather Service Bay Area warned that this new storm’s impact could be even worse than the last one.

“The mid to late week system looks like it will cause dangerous situations,” NWS Bay Area wrote.

KRON4 Chief Meteorologist Lawrence Karnow agreed. “This is going to be a lot windier than the previous storm. Wind damage could be a really big issue, especially late Tuesday night into Wednesday morning. And heavy, heavy rain.”

Mountain wind gusts at the Bay Area’s highest elevations could reach 70 mph.

“This will be a strong wind event,” NWS Bay Area forecasters wrote. “Bottom line for this week is that for the Jan 4-5 storm, expect similar impacts or worse compared to what happened on Dec 31.”

“Rapid rises on creeks and streams, downed trees, multiple mudslides across the region, power outages. In addition, this third atmospheric river since Dec 26 means we could see some of our main stem rivers approach or reach flood stage. One area of concern is the Russian River near Guerneville. For creeks and streams that flooded yesterday…we’ll likely see a repeat this week. Stronger winds with saturated soils will enhance storm damage. Additional concerns with this system is the orientation of the main rain band. Southerly winds will become dangerously strong. Recent forecast updates are showing some slowing of this system, both before and after it moves inland. Behind the main rain band, scattered showers linger through Thursday,” NWS Bay Area wrote.

NWS rainfall totals forecast between Tuesday night through Friday morning:

  • Coastal Mountains in the North Bay: 4.5″ – 6.5″ (locally up to 7.5″ over higher peaks)
  • Interior North Bay: 2.75″ – 5″
  • Around the San Francisco Bay (including East & South Bay): 1.5″ – 3″
  • The Santa Cruz Mountains: 3.5″ – 6″ (up to 7″ over higher peaks)
  • Big Sur Coast in Monterey County: 4.5″ – 6.5″ (up to 8″ over higher peaks)

Bomb Cyclone

Meteorologist Ryan Maue tweeted that a “bomb cyclone” will appear over the Pacific Ocean on Tuesday. The cyclone will remain far offshore from California.

“A rare U.S. west coast ‘bomb cyclone’ will form Tuesday over the Pacific Ocean. The storm center will remain well off-shore w/hurricane force winds but an ‘atmospheric river’ or front will lash the coast on Wednesday,” Maue tweeted.

Daniel Swain, a climate scientist with UCLA, wrote on Twitter, “The next inbound storm looks like it will be quite strong. A rapidly deepening surface low (i.e., meteorological ‘bomb cyclone’) will remain well offshore, but the associated warm and cold fronts will bring widespread heavy rain and strong winds to NorCal.”

Swain wrote, “My main concern, right now, is portion of this that will fall rather quickly over 6-8 hour period on Wed as another strong storm makes landfall. There will be pretty high potential for flooding, including some serious/life-threatening flooding, across broad swath of NorCal.”