Updated 1/7/2017 11:52AM PST
A VERY WET STORM SYSTEM IS APPROACHING MARIN THIS WEEKEND. RAIN WILL START SATURDAY AND BECOME EXTREMELY HEAVY SATURDAY NIGHT THROUGH SUNDAY NIGHT. HEAVY RAIN ON ALREADY SATURATED SOILS IS PREDICTED TO LEAD TO FLASH FLOODING OF AREA STREAMS AND RIVERS, ESPECIALLY IN THE ROSS VALLEY.
"The National Weather Service reports that the "atmospheric river" has shifted north of its original predicted path, which means nearly TWICE THE AMOUNT OF RAINFALL originally predicted for Marin County. The start of the storm is predicted to be at 4:00PM Saturday and will continue until late Sunday. The highest intensity is still expected to be from 10:00PM Saturday to 4:00AM Sunday.
The NWS has indicated a high confidence level for Corte Madera Creek over-topping between 4-6AM Sunday morning!
The incoming storm is now predicted to bring 3” to 5” of rain along the Marin County coastal and bay-side lower elevations, with coastal mountains expecting 5” to 10”. Mt. Tam may receive up to 12” of rain between 4PM today and 10PM Sunday night. Intensities at times are predicted to be at least 1.0” to 1.5”/hour throughout the County.
A predicted high tide at 07:22AM of 6.45-ft means that the tide will be coming-in during the most intense part of the storm. A residual range from 0.5-ft to 2.0-ft may occur as a result of the high winds and lower pressures. As a result, flooding in areas influenced by tidal waters is likely during this time. These areas may include, but are not limited to, Mill Valley, Kentfield, Ross, San Anselmo, Larkspur, Corte Madera, Muir Woods, Muir Beach, GGNRA, Stinson Beach, Novato, San Rafael, Seminary Drive and the Highway 101/1 interchange at Manzanita.
PRECIPITATION OUTLOOK IN KEY AREAS FROM 4:00PM SATURDAY TO 10:00PM SUNDAY:
- 3” to 5” in lower elevations of Marin
- 5” to 10” over the coastal hills and mountain ranges
- Up to 12” over Mt. Tamalpais
High-tides for the next week are on an upward trend. With tide residuals reaching above predicted tops, tidally influenced flood-prone areas will likely see flooding on Saturday and Sunday. For Monday through Thursday, predicted heights are expected to be above 6.5-ft, so expect flooding in flood-prone areas over these three days.
A "FLASH FLOOD WATCH" MEANS THAT CONDITIONS ARE PREDICTED TO DEVELOP THAT MAY LEAD TO FLASH FLOODING. FLASH FLOODING IS AN EXTEMELY DANGEROUS SITUATION. YOU SHOULD MONITOR FORECASTS AND BE PREPARED TO TAKE ACTION IMMEDIATELY SHOULD "FLASH FLOOD WARNINGS" BE ISSUED.
Monitor the Ross Valley Fire Department Creek Levels and Weather page here...