The northern end of the Petaluma River is expected to flood within the next 18 hours, Petaluma police and fire officials warned this evening.
The Sonoma County Emergency Coordinator has said that heavy rains expected this evening will arrive earlier and bring more rain than initially predicted, according to a statement from Petaluma Fire Battalion Chief Jeff Holden.
"We will be monitoring the streams and gauges but please don't expect any alerts from the from the Fire Department during this time frame," Holden said. "If flooding does occur, we will be out isolating flood areas and responding to calls for assistance." Residents are urged to call 911 if they need assistance.
The Napa and Russian rivers are expected to reach flood stage Sunday and Monday, according to the National Weather Service.
The third storm in recent days is expected to arrive Saturday evening and continue into Sunday, bringing an additional seven to eight inches of rain in higher elevations. The North Bay is expected to see the heaviest rains, according to the weather service forecast. The Russian River will reach flood stage in Guerneville around 2 a.m. Monday morning, with water at 31.7 feet, and crest around noon at 35 feet, the National Weather Service said.
The Napa River is expected to reach flood stage in St. Helena around noon on Sunday, with water at heights of 15.9 feet, and crest around 3 p.m. at 17.8 feet, the National Weather Service said.
In Napa it is expected to reach flood stage around 1 p.m. Sunday, with water at heights of 25.2 feet, and between 5 and 6 p.m. with water levels reaching nearly 27 feet. The flooding in Napa is expected to focus in a "largely agricultural and minimally developed area" around Oak Knoll Avenue, about five miles north of the city itself, according to Napa Community Outreach Coordinator Barry Martin. Napa officials project that the river will remain mostly within its banks south of Lincoln Avenue, but there could be minor flooding near the Lincoln Avenue Bridge.
The lower portion of Veterans Memorial park could also be inundated, as designed by city flood control projects, Martin said.
Veterans Memorial Park and the Riverfront Promenade in Napa, as well as Oxbow Preserve Park will be closed to the public throughout Sunday, Martin said. The National Weather Service has also issued a flash flood watch for the North Bay through Monday and a wind advisory from 10 p.m. Saturday through 10 a.m. Sunday, Martin said. Winds are expected to reach 20 to 30 mph at lower elevations and up to 50 mph gusts at higher elevations.