A series of storms will parade through the Western United States over the next five days with another strong storm on Monday and Tuesday, forecasters warn. And the pattern could last through mid-January.
“When all said and done, we are looking at several more inches of rainfall through the middle of next week with moderate to high confidence of even more rain through mid-month,” according to forecasters at the San Francisco Bay Area office of the National Weather Service.
“Additional rounds of heavy rainfall with ample runoff issues are likely to persist through early next week in a dangerously wet pattern with multiple atmospheric rivers,” meteorologists at the national Weather Prediction Center said.
Here is a day-by-day breakdown of what is expected and where.
Thursday
An atmospheric river continues to stream moisture over California on Thursday, but is forecast to weaken as the day progresses.
“Coastal areas of California and the Sacramento Valley are most at risk,” the prediction center forecasters said early Thursday morning.
These forecasters warned that rain rates of over one inch per hour could produce rapidly rising water in rivers and streams, and create mud or rock slides.
The individual rain storms are expected to be spotty, but anywhere heavy rain falls it could lead to flooding because the ground may be oversaturated — like a sponge that is soaked and can’t absorb more water.
These saturated soils, combined with wind gusts of 50 miles per hour predicted on Thursday, may make trees more susceptible to being blown down.
In the mountains above 5,000 feet of altitude in Northern and Central California, snow will continue to fall at rates of more than three inches an hour at times, creating dangerous travel conditions.
Things should wind down by Thursday evening, when most of the heavy rainfall comes to an end. But the reprieve will be brief.
Friday
Much of California is expected to get a break on Friday from the rainfall as the stream of moisture flows into southwestern Oregon and Northern California on Friday.
“Peak rainfall amounts into Northern California’s coastal mountains could exceed four inches during this period into very late Friday night,” forecasters at the prediction center said.
Saturday
Widespread rainfall and high-elevation snow is expected to return on Saturday to most of California. Southern California may escape with another day without precipitation.
The moisture should slowly drift down through California during the day with the heavier precipitation mostly over Central and Northern California.
The first burst of rain is expected in the morning, with more rain inland toward Sacramento and the Sacramento Valley. By evening, another dose of heavy rain is expected further south over the Bay Area.
Sunday
Things begin to look dreary again across the most of the state; even Southern California most likely gets the moisture back.
“The storm door will remain open this weekend all the way through end of next week,” forecasters at the Los Angeles office of the Weather Service said.
The biggest areas of concern for excessive rainfall are still limited to Northern California. But that changes on Monday.
Monday
Monday will most likely see another strong atmospheric river develop, which will once again deliver widespread moderate to heavy rain, strong southerly winds and heavy snow in the higher elevations.
The plume of moisture will first move over the Bay Area during the day.
It’s a little early to know exactly how much rain will fall with this robust storm system on Monday, but the prediction center forecasters said in their extended outlook, “look for multiple inches over a broad area of Northern and Central California.”
“The cumulative effects of repeated rounds of moderate to heavy rain from preceding storms may lead to a higher potential for more widespread flooding with increasingly severe impacts with this storm,” the Sacramento weather office said on Thursday.
By Monday night into Tuesday, the heavier plume of moisture is likely to move south over the Los Angeles area.
“Its still early and the forecast could change,” the Los Angeles-based forecasters warned.
Beyond Monday
There isn’t great news in the forecasts. It looks like the storms will take a brief lull, but forecasters believe another moderate to strong atmospheric river could take aim at the West Coast next Thursday.
