A Healthy Shot of Rain -- and Possible Harbinger of Series of Storms

Update, 11:20 a.m. Friday: Selected rainfall totals for the 48 hours ending at 10 a.m. Friday:

Update, 3:50 p.m. Thursday: The National Weather Service is calling for a second round of rain Thursday and early Friday from a storm system that has been pounding the Pacific Northwest for days.

Most locations in the Bay Area will pick up an additional one-quarter to one-half inch of rain before the storm tapers off Monday morning. Hills and locations from northern Sonoma County to the Santa Cruz County will see higher totals.

Forecasters are also warning of "excessively large surf."

The weather service says waves up to 22 feet can be expected along the coast from Sonoma County south through Big Sur, and cautions the ocean conditions carry a triple threat: Waves can be expected to run high up onto beaches and rocks, increasing the risk of people being washed away; the surf will be accompanied by strong rip currents, a potentially deadly hazard to anyone who enters the water; and waves will trigger coastal flooding both inside and outside San Francisco Bay during high tide occurring at midmorning Friday.

Moist but non-rainy weather is forecast for most of the region from late Friday through late Saturday, when another storm is expected to resume again in northern Sonoma County and spread occasionally heavy rain across the rest of the region Sunday. Clearing is expected Monday, with the possibility of more storms arriving later in the week.

Original post: The Bay Area is getting a taste of the extravagantly stormy weather deluging California's North Coast and much of the Pacific Northwest. And the rain that arrived late Wednesday could just be a taste of what's in store between now and Christmas.

Two rounds of rain that began falling Wednesday afternoon in northern Sonoma County have dropped more than 3 inches at the wettest reporting station, a spot west of Healdsburg called Venado (that's the Spanish word for "deer" if you're keeping track at home).

Other notable totals: Middle Peak, on Mount Tamalpais, which has recorded 2.86 inches; Los Trancos, in the hills above Palo Alto, which got 1.29 inches; and Vollmer Peak, in the Berkeley Hills, which has gotten .71 inch.

Lower elevations have generally received much lighter rain -- .25 inch in San Francisco, .21 in Richmond, .14 in downtown Oakland, .08 at Moffett Field and .04 at San Jose International Airport.

A second shot of precipitation is expected to sweep across the region Thursday afternoon and into early Friday.

Meantime, heavy snow is forecast for the Sierra Nevada, with between 18 and 36 inches expected at higher elevations by the time the current storm passes.

The National Weather Services says Thursday's storm is part of a series, with two more systems expected to bring rain Sunday and Monday. Another storm is possible by the middle of next week --- and another one after that, the weekend of Dec. 19-20. More details on that forecast to come.