PROJECT ALERT NOTICE (CA) Flooding continues for California - Day 12

Date: Sat, 18 Feb 2017 12:39:44 EST

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

A series of atmospheric river storms will bring rain and snow to California today and continuing possibly through the end of next week (Feb 23). Light precipitation is expected today and tomorrow for most of California. On Monday, a stronger storm expected to bring heavy precipitation and as much as 6 inches of rainfall to parts of the Sierra Nevada, including Oroville, CA. 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 southern and northern California. Major flooding is expected, along with increased potential for flash floods, landslides, and debris flows, especially in recent wildfire burn areas.

The NOAA/NWS California Nevada River Forecast Center reports many California rivers currently exceed or are expected to exceed flood or monitor stage on Monday, including 13 gage locations along the Sacramento River, and 4 gages on the San Joaquin River.

The California Water Science Center (CAWSC) has 13 crews responding to this event today from the following service areas: Poway, CA (4); Santa Maria, CA (4); Redlands, CA (3); Santa Cruz, CA (1); and Ukiah, CA (1). Most crews are performing high-flow measurements, but some are also performing service repairs or maintenance. Flood response by the CAWSC will be assessed continuously as these storms develop and as basins respond.

Yesterday’s storm brought substantial rainfall to southern California, and resulted in massive flooding. CalTrans reports numerous road closures in central and southern California due to flooding, landslides, sinkholes, and rock slides. A USGS precipitation gage located east of Santa Barbara (343120118533301) reported 6.5 inches of rain yesterday. Eighteen USGS gages in and around the Santa Barbara area recorded top 10 peakflows for the period of record. For example, the USGS gage at Sisquoc River near Garey (11140000) recorded the second highest peakflow since the gage was established in 1940. Field crews responding to this event reported extensive flooding and measurement challenges due to heavy debris in streams. During yesterday’s event, USGS crews from the Santa Maria service area also conducting water-quality sampling for the USGS San Antonio Creek Project, a study that is investigating whether streamflow infiltration during winter storm events is a major source of recharge to the San Antonio Creek groundwater system.

At least 8 gages in California are experiencing data transmission or data-quality issues as a result of this most recent storm. Questionable data have either been removed from NWISWeb or warning statements have been added to qualify the data.

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. Additional flood response crews may deploy tomorrow, and into next week in response to these events. Updates will continue to be provided during the course of this event.