PROJECT ALERT NOTICE (CA) PROJECT ALERT NOTICE (CA) California experiencing a wave of AR storms—Continued, Day 9

Date: Thu, 12 Jan 2017 16:15:55 EST

Summary: Multiple atmospheric rivers continue to bring heavy rainfall and snow to many parts of California this week.

Today, flooding and elevated streamflows continue as streams across California respond to over a week of storm events that brought well above-average precipitation to many parts of the State. Light to moderate rainfall is expected today, with snow accumulations at higher elevations. Flood watches and winter storm warnings remain in effect for central California and the Sierra Nevada, respectively. Although light showers are expected tomorrow in parts of southern California, precipitation is expected to finally end by this evening. This break in the weather may be brief, however, as another storm system is currently predicted to bring additional precipitation to parts of California beginning next Tuesday.

Over 60 percent of USGS streamgages in California remain above the 90th percentile of normal flow today. Since this storm system began, 112 USGS streamgages in California have recorded top 10 peakflows, with more than half (58) of those gages having 20 plus years of record, and over a quarter (29) of those gages having 50 plus years of record.

The California Water Science Center (CAWSC) has 17 crews responding to this event today from the following service areas: Ukiah, CA (3); Redding, CA (1); Eureka, CA (1); Santa Cruz, CA (4); Redlands, CA (2); Santa Maria, CA (2); Truckee, CA (1); and Sacramento, CA (3). More crews are planned to deploy tomorrow.

The USGS Truckee Field Office is open today, but widespread power outages continue for this area. No USGS data interruptions are currently reported in this region.

Traffic and road closures have been a challenge for many USGS crews. This morning, CalTrans reports numerous road closures around the Bay area due to flooding and in the Sierra Nevada due to winter conditions.

A USGS media event is planned for today at 11446500, American River at Fair Oaks, CA where media are invited to accompany USGS field crews as they measure streamflow during a release from Folsom Dam. This work is conducted by the USGS in coordination with the Bureau of Reclamation for verification purposes.

One USGS crews is also out today performing streamflow measurements in coordination with Alameda County Water District during emergency flood control releases from Del Valle Dam, which is part of the South Bay Aqueduct.

Currently, 9 out of the 500 plus streamgages operated by the California Water Science Center have sustained damages or are experiencing data interruptions as a result of recent storms. Cooperators have been notified and crews are working on repairs, but streamgages with more extensive flood damage may require additional work and time to restore operations. For example, streamgage 11285500, Tuolumne River above Wards Ferry Bridge near Groveland CA, which is located downstream of the 2013 Rim Fire burn area, was likely submerged by fast rising waters and backwater from New Don Pedro Dam, located about 20 river miles downstream of the gage. This road to this station is currently closed due to winter weather conditions.

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.