From the Department of Water Resources:
A Water Year 2014 Water Supply Index (WSI) forecast for conditions as of December 1, 2013 is posted at http://cdec.water.ca.gov/cgi-progs/iodir/WSI.2014. The accretions forecast will be sent at a later time.
This WSI forecast is based on the precipitation and flows through November 2013 and can be summarized as follows:
Sacramento River Unimpaired Runoff Water Year Forecast(50 percent exceedence) 12.2 MAF(67 percent of average) Sacramento Valley Index (SVI)(50 percent exceedence) 5.6(Dry) San Joaquin Valley Index (SJI)(75 percent exceedence) 1.4(Critical)
Unimpaired flows, for the first two months of the Water Year, have occurred at average rates of 49 percent, 22 percent, and 34 percent of average for the Sacramento Valley Index four rivers, the San Joaquin Valley Index four rivers, and the Tulare Lake basin, respectively. During November, the four rivers in the Sacramento Valley and the four rivers in the San Joaquin Valley Index flowed at an average rate of 38 and 16 percent of average. Tulare Lake basin flows were 32 percent of normal.
Precipitation in October and November for the Sacramento River Region is at 24 percent of average, the San Joaquin River region is at 29 percent of average, and the Tulare Lake region is at 45 percent of average. Statewide, cumulative water year precipitation through November is 6 percent of the expected water year total; last year at this time it was 110 percent of average.
The Northern Sierra 8-Station Precipitation Index gained 0.8 inch in October (27 percent of average) and 1.7 inches in November (27 percent of average). The 8 station seasonal average is 26% of normal including precipitation through December 2. The San Joaquin 5-Station Index gained 0.9 inch in October (45 percent of average) and 1.0 inch in November (21 percent of average). The 5 station seasonal average is 26% to date through December 2.
The snowpack as of the morning of December 6 is 10, 20 and 36 percent of normal to date for the Northern, Central and Southern Sierra regions, respectively. The statewide percent of average to date is 21, and the statewide percent of April 1 is only 4. Last year at this time the statewide percent of average snow water content was 99.
Weather and Climate Outlooks:
The latest weather forecasts for the Sacramento Valley Index Region indicate up to 0.8 inch today and 0.2 inch for tomorrow and the San Joaquin Valley Index Region can expect up to 0.5 inch today and 0.2 inch for tomorrow. The remaining four days show no precipitation throughout the state. The first three days of the six day period will be cold in the Sacramento region with snowlines ranging between 1,000 to 3,000 feet. Then there is a warming trend over the last three days with freezing levels rising up to 8,000 feet. The first two days will be cold in the San Joaquin region with snowlines ranging between 2,000 to 4,000 feet. Then there is a warming trend over the last four days with freezing levels rising up to 10,000 feet.
The NWS Climate Prediction Center three-month (December-January-February) forecast, posted November 21, also suggests equal chance of either above or below normal precipitation and temperature for the entire state, except a sliver of the southeastern corner of the state where there is an increased chance of above normal temperatures and below normal precipitation.
The next WSI forecast should be available on January 9, 2014. If you have any questions regarding this forecast, please contact a member of the Snow Surveys staff.
Full Natural Flow Data:
Latest Northern Sierra 8-Station Precipitation Index
Latest San Joaquin 5-Station Precipitation Index
Latest Snow Sensor Report
Latest Statewide Summary of Snow Water Equivalents
Extended Regional Forecasts:
California Nevada River Forecast Center 6 Day QPF and Snow Level Forecast
Climate Prediction Center One-Month Outlook Forecasts
Climate Prediction Center Three-Month Outlook Forecasts
U.S. Seasonal Drought Outlook
Weather Forecast Office California Service Area-Products