Enjoy your dry Monday, but don't get too used to the non-rainy weather we're experiencing across the Bay Area. Forecasters far and wide and their mathematical models expect the coming week to range from wet to inundated, depending on where you live.
The latest thinking from National Weather Service forecasters is that the next round of rain will begin across most of the region, from the coastal hills of Sonoma to the Santa Cruz Mountains, by sometime Tuesday afternoon.
The storm will be a two-round event. The first round, lasting until late Wednesday night, ought to be characterized by relatively light rain, with inland totals forecast to range from about 1.5 inches in northern Sonoma County to just over .10 in San Jose, according to one NWS analysis.
That's just the prelude to a windy, intense Round 2 forecast to begin late Wednesday and continue through early Friday, with nearly 2 inches of rain projected to fall over northern Sonoma County to as much as an inch in San Jose. Wind gusts are forecast throughout the region, topping 50 mph in the Diablo Range east and south of San Jose and in the coastal mountains south of Monterey.
Workweek rainfall totals could reach 7 inches or more in the hills of western Sonoma and 5 inches in the Santa Cruz Mountains.
There's more to Northern California weather than what happens in our collection of Bay Area counties, and Round 2 of the upcoming storms is expected to have a big impact on the state's interior.
In the Sierra Nevada, snow levels are expected to rise above the level of Donner Pass and Echo Summit as the first storm takes hold Tuesday. One popular seasonal weather site, Tahoe Daily Snow, forecasts little snow accumulation through early Thursday. But the second round of storminess later in the week could bring as much as 3 feet of snow to the higher elevations around Lake Tahoe. Over the weekend, models had suggested the central Sierra could get as much as 8 feet of snow this week.
Very heavy precipitation is possible over a big swath of Northern California, prompting a flood watch covering the Central Valley from Modesto to Redding and upland areas stretching from Mount Shasta and down the Sierra Nevada foothills to near Yosemite.
The National Weather Service in Sacramento says some of those areas will get 3 to 8 inches of rain on top of the soaking they got over the last several days.
The rains have already triggered significant rises on some rivers, including the main stem of the Sacramento. The California-Nevada River Forecast Center says the Sacramento will crest late this week above flood or monitor stage at several locations. That will inundate some low-lying areas and cause the river to cascade into bypasses -- overflow channels -- in the central Sacramento Valley.
Several coastal rivers are also expected to be at or near flood stage. Those include the Eel River and the Navarro River, the latter a Mendocino County stream on which rapid water level changes are the norm during stormy winter weather.
The Russian River is expected to hit monitor stage in Hopland, on the southern edge of Mendocino County. Brief flooding of some local roads can be expected if that forecast bears out. The Russian is expected to stay well below monitor stage at Healdsburg and Guerneville.