Welcome to the 2015 Water Year season of water supply forecasting! The first water supply forecast has been completed.
A Water Year 2015 Water Supply Index (WSI) forecast for conditions as of December 1, 2014 is posted at http://cdec.water.ca.gov/cgi-progs/iodir/WSI.2015. The accretions forecast will be sent at a later time. This WSI forecast is based on the precipitation and flows through November 2014 and can be summarized as follows:
Sacramento River Unimpaired Runoff Water Year Forecast(50 percent exceedance)
(75 percent of average)
Sacramento Valley Index (SVI)(50 percent exceedance)
San Joaquin Valley Index (SJI)(75 percent exceedance)
Unimpaired flows for the 2014-15 water year have run at the following rates of average:
October + November Runoff (%)
November Runoff (%)
Sacramento Valley Index (4 rivers)
San Joaquin Valley Index (6 rivers)
Tulare Lake basin (4 rivers)
Precipitation for the 2014-15 water year accumulated at the following rates of average:
The snowpack as of the morning of December 8 stands at the following (based on snow sensors):
Snow Water Equivalent (inches)
% of Average (Apr. 1)
% of Average (Dec. 8)
Weather and Climate Outlooks:
Unsettled conditions are forecasted this week for much of California. Periods of widespread, minor precipitation are expected through Wednesday. A major storm (possibly the strongest in 6 years) is expected to reach the state late Wednesday and last into Friday. Areas of moderate to heavy rainfall are expected, along with significant snowfall accumulation in the Sierra. Strong, gusty winds are expected at times. Five-day precipitation totals may reach above 6 inches in coastal and mountain regions of northern California. Up to 3 inches may be expected in the coastal and mountain regions of central and southern California. Freezing levels will be above 9,000 feet for the first part of the storm but are expected to drop to as low as 5,000 to 6,000 feet in some areas during the latter part of the storm.
The NWS Climate Prediction Center (CPC) one-month outlook for December, valid November 30, indicates increased chances of above normal precipitation and temperature for the entire state.
The CPC three-month (December-January-February) outlook, posted November 29, indicates increased chances of above normal temperature for the entire state. It also suggests equal chances of above or below normal precipitation for Sacramento northward and increased chances of above normal precipitation Sacramento southward.
ENSO-neutral conditions continue. Positive equatorial sea surface temperature anomalies continue across the Pacific Ocean. There is approximately a 65 percent chance that El Niño conditions will be present during the Northern Hemisphere winter and last into the Northern Hemisphere spring 2015.
The next WSI forecast for conditions as of January 1 should be available on January 9, 2015. If you have any questions regarding this forecast, please contact a member of the Snow Surveys staff.