'Atmospheric River' Forecast To Drench Petaluma, North Bay

PETALUMA, CA — By Sunday morning, rain will become heavy in the North Bay as the long-awaited atmospheric river takes aim at Northern California, forecasters with the National Weather Service San Francisco Bay Area said in a special weather statement Thursday.

It is one of two storm systems expected to impact the North Bay through Monday, according to a special weather statement issued at 4:57 p.m. Thursday for the Coastal North Bay, Point Reyes National Seashore, North Bay interior valleys and North Bay mountains.

The special weather statement applies to the North Bay communities of Santa Rosa, South Santa Rosa, Napa, San Rafael, Petaluma, Novato, Rohnert Park, Cotati, Angwin, Lagunitas-Forest Knolls and Woodacre:

"Light rain is already falling in the North Bay and will continue overnight. A cold front will reach the North Bay after midnight and bring a band of rain through the Bay Area for the Friday morning commute.

"Inland locations that haven`t received much rain the last few days should expect to receive some light rainfall Friday morning. The morning commute will be adversely impacted with wet roadways. Slow down, use wipers and headlights and plan for extra time to reach your destination Friday morning.

"A brief break in the weather as dry weather returns Friday afternoon through Saturday afternoon. Use this window of time for any storm preparations.

"Light rain will start in the North Bay Saturday evening. By Sunday morning rain will become heavy in the North Bay as the long-awaited atmospheric river takes aim at Northern California. The band of heavy rain is then forecast to drift southward through the Bay Area during the day Sunday reaching the Santa Cruz Mountains by late afternoon.

"The heavy rain will then drift into the Central Coast by Sunday evening as precipitation begins to wind down across the greater Bay Area. Several inches of rainfall are forecast across the region with higher amounts in the hills. Now is the time to clear storm drains and gutters.

"In addition to heavy rain, a period of gusty winds will accompany the front on Sunday. Drought-stressed trees will be susceptible to toppling leading to possible power outages.

"Burn scars throughout the state will be prone to debris flows with likely significant impacts across the Sierra. Plan your travel accordingly. Rain will taper to showers by Monday."

7-Day Forecast For Petaluma

The following seven-day weather forecast is from the National Weather Service San Francisco Bay Area:

Thursday Night: Rain. Low around 53. South southeast wind 5 to 10 mph, with gusts as high as 20 mph. Chance of precipitation is 90%. New precipitation amounts between a quarter and half of an inch possible.

Friday: Rain, mainly before noon. High near 65. Southwest wind 6 to 15 mph becoming west northwest in the morning. Winds could gust as high as 24 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and a quarter of an inch possible.

Friday Night: Patchy fog before midnight, then patchy fog after 3am. Otherwise, mostly cloudy, with a low around 48. Calm wind becoming west northwest 5 to 8 mph after midnight.

Saturday: Rain likely, mainly afternoon. Patchy fog before noon. Otherwise, mostly cloudy, with a high near 63. West wind 5 to 9 mph becoming south in the afternoon. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Saturday Night: Rain. Low around 52. East southeast wind 7 to 10 mph becoming south in the evening. Winds could gust as high as 25 mph. Chance of precipitation is 90%. New precipitation amounts between a half and three-quarters of an inch possible.

Sunday: Rain. The rain could be heavy at times. High near 64. Chance of precipitation is 100%. New precipitation amounts between 2 and 3 inches possible.

Sunday Night: Rain. Low around 50. Chance of precipitation is 100%.

Monday: Rain. Mostly cloudy, with a high near 63.

Monday Night: A chance of rain. Mostly cloudy, with a low around 47.

Tuesday: Rain likely. Mostly cloudy, with a high near 64.

Tuesday Night: A chance of rain. Mostly cloudy, with a low around 50.

Wednesday: A slight chance of rain. Patchy fog. Otherwise, partly sunny, with a high near 71.

Wednesday Night: Mostly clear, with a low around 48.

Thursday: Patchy fog. Otherwise, mostly sunny, with a high near 74.