PROJECT ALERT NOTICE (CA) Flooding continues for California

Date: Sun, 19 Feb 2017 21:11:40 EST

Summary: Flooding continues in California as another series of AR storms bring more rainfall to the region.

A series of atmospheric river storms will bring rain and snow to California today and continuing through Wednesday. Today, most of California will experience light precipitation or scattered showers; however, tomorrow a stronger storm expected to bring heavy precipitation and as much as 4-6 inches of rainfall to parts of northern California and the Sierra Nevada. The National Weather Service (NWS) has issued a winter weather advisory for the Sierra Nevada, and flood warnings or flash flood watches for numerous counties in northern California. Major flooding is expected, along with increased potential for flash floods, landslides, and debris flows.

The NOAA/NWS California Nevada River Forecast Center reports many California rivers remain above flood or monitor stage today, including 13 gage locations along the Sacramento River, and 4 gages on the San Joaquin River. The San Joaquin River near Vernalis (11303500) exceeded danger stage today and is predicted to remain above this stage for several days. The designation of danger stage is used for flood control projects where an elevated stage poses an extreme danger with threat of hazard to life and property in the event of a levee failure.

The California Water Science Center (CAWSC) has no crews responding to this event today or tomorrow, but does plans to deploy crews on Tuesdays in response to Mondays storm event.

On Tuesday, crews in northern California will perform high-water measurements following Monday’s heavy rainfall. Crews in southern California will be busy making repairs, flagging high-water marks, and performing indirect flood measurement surveys. These crews will assess damages and the extent of Friday’s storm, which destroyed many staff and crest stage gages, and exceeded the rating at several locations. For example, Cajon Creek (11063510) went from 50 cfs to over 6,000 cfs in less than 30 minutes, before exceeding the rating for this site. This gage is located along the 15 freeway in San Bernardino below Cajon Pass, just downstream of where Fridays flooding caused two lanes of the highway to collapse sending a Firetruck over the edge.

Managers from the CAWSC remain in contact with water resource managers from the Bureau of Reclamation, the Army Corps of Engineers, and the California Department of Water Resources to coordinate USGS sampling or high-water measurements.

No safety issues have occurred during this series of storms and all staff have followed USGS field reporting and safety protocols. Updates will continue to be provided during the course of this event.