From the Department of Water Resources:
Forecast Summary:
A Water Year 2020 Water Supply Index (WSI) forecast for conditions as of December 1, 2019 is posted at http://cdec.water.ca.gov/reportapp/javareports?name=WSI. The WSI forecast is based on the precipitation and runoff (full natural flow) through November 2019 and can be summarized as follows:
Sacramento River Unimpaired Runoff Water Year Forecast (50 percent exceedance)
13.6 (76 percent of average)
Sacramento Valley Index (SVI) (50 percent exceedance)
7.3 (Below Normal)
San Joaquin Valley Index (SJI) (75 percent exceedance)
2.2 (Dry)
Runoff: Unimpaired flows in Percent of Average for Water Year 2020
Oct Runoff
Nov Runoff
Oct-Nov Runoff
Sacramento Valley Index (4 rivers) 89 45 61 San Joaquin Valley Index (6 rivers) 92 33 52 Tulare Lake Basin (4 rivers) 110 77 91
Precipitation: Cumulative Precipitation in Percent of Average for Water Year 2020
Regional Precipitation Indices As of December 9, 2019 Northern Sierra 8-Station Index 77 (9.5 inches) San Joaquin 5-Station Index 96 (8.4 inches) Tulare Basin 6-Station Index 100 (5.6 inches)
Monthly Precipitation in Percent of Average for Water Year 2020 for Regional Precipitation Indices
Regional Precipitation Indices Oct Nov Dec (09) Northern Sierra 8-Station Index 3 43 69 San Joaquin 5-Station Index 0 69 82 Tulare Basin 6-Station Index 0 106 51
Snowpack:
The snowpack as of the morning of December 9, 2019 stands at the following (based on snow sensors)
Region Snow Water Equivalent (inches) % of Average (Apr 1) % of Average (Dec 9) Northern 5.8 20 95 Central 7.5 25 115 Southern 6.7 26 142 Statewide 6.8 24 116
Weather and Climate Outlooks:
According to the CNRFC 6-day forecast, a weak system approaching Northern California coast on Tuesday will bring some precipitation to northern California. Best chances of precipitation are along the coast from San Francisco to the California-Oregon border; up to 0.50 inches. Elsewhere, the precipitation totals will be around 0.1 inch. More precipitation is expected over northern California including the Sierra starting Thursday, continuing through Saturday. The Klamath and the North Coast are forecasted to receive the most: up to 2 inches from Thursday to Saturday. The American, Feather, and Yuba basins are forecasted to receive up to 1 inch over the same period. Freezing elevations for major basins in the State start off fairly high (8,000 to 10,000 feet). But later in the week and into the weekend, elevations drop appreciably, hovering between 4,000 and 5,000 feet.
The NWS Climate Prediction Center (CPC) one‐month outlook for December, issued on November 30, 2019, points to increased chances of above normal temperatures for the entire State except for the Sierras and along the California- Nevada border, where equal chances of above and below normal temperatures are expected. The same outlook suggests increased chances of above normal precipitation for the entire State.
The CPC three‐month (December‐January‐February) outlook, issued on November 21, 2019, points to increased chances of above normal temperatures for the entire State. The same outlook suggests chances of below normal precipitation for the entire State except along the California-Oregon border, where equal chances of above or below normal precipitation is expected.
According to the latest El Niño/Southern Oscillation (ENSO) discussion issued by the Climate Prediction Center on December 9, 2019, ENSO-neutral conditions are present. Equatorial sea surface temperatures are near-to-above average across much of the Pacific Ocean. ENSO-neutral is favored during the Northern Hemisphere winter 2019-20 (70% chance), and continuing through spring 2020 (60 to 65% chance).
Next Update:
The next WSI forecast for conditions as of January 1, 2020 will be available on January 9. If you have any questions regarding this forecast, please contact a member of the Snow Surveys and Water Supply Forecasting Section.
Important Links:
Full Natural Flow Data:
- Daily FNF: http://cdec.water.ca.gov/reportapp/javareports?name=FNF
- Monthly FNF: http://cdec.water.ca.gov/reportapp/javareports?name=FNFSUM
- Seasonal FNF: http://cdec.water.ca.gov/reportapp/javareports?name=FLOWOUT
Precipitation Data:
- Latest Northern Sierra 8-Station Precipitation Index: http://cdec.water.ca.gov/cgi-progs/products/TAB_ESI.pdf
- Latest San Joaquin 5-Station Precipitation Index: http://cdec.water.ca.gov/cgi-progs/products/TAB_FSI.pdf
- Latest Tulare Basin 6-Station Precipitation Index: http://cdec.water.ca.gov/cgi-progs/products/TAB_TSI.pdf
Snow Data:
- Latest Snow Sensor Report: http://cdec.water.ca.gov/reportapp/javareports?name=PAGE6
- Latest Statewide Summary of Snow Water Equivalents: http://cdec.water.ca.gov/reportapp/javareports?name=DLYSWEQ
Extended Regional Forecasts:
- California Nevada River Forecast Center 6 Day QPF and Snow Level Forecast: http://www.cnrfc.noaa.gov/awipsProducts/RNOHD6RSA.php
- Climate Prediction Center One-Month Outlook Forecasts: http://www.cpc.ncep.noaa.gov/products/predictions/30day/
- Climate Prediction Center Three-Month Outlook Forecasts: http://www.cpc.ncep.noaa.gov/products/predictions/long_range/seasonal.php?lead=1
- U.S. Seasonal Drought Outlook: http://www.cpc.ncep.noaa.gov/products/expert_assessment/sdo_summary.html
- Weather Forecast Office California Service Area-Products: http://www.cnrfc.noaa.gov/forecasts.php
- El Niño Southern Oscillation (ENSO) Conditions and Weekly Discussion (including La Niña): http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf
Snow Surveys and Water Supply Forecasting Section Contact Information:
- Sean de Guzman, Section Chief (sean.deguzman@water.ca.gov) (916) 574-2208
- John King (john.j.king@water.ca.gov) (916) 574-2637
- Andy Reising (andrew.reising@water.ca.gov) (916) 574-2181
- Ashok Bathulla (ashok.bathulla@water.ca.gov) (916) 574-2634
- Lauren Miller (lauren.miller@water.ca.gov) (916) 574-1433
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