WATER SUPPLY INDEX for January 1, 2019
From the Department of Water Resources:
A Water Year 2019 Water Supply Index (WSI) forecast for conditions as of January 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 December 2018 and can be summarized as follows:
Sacramento River Unimpaired Runoff Water Year Forecast
(50 percent exceedance)
(78 percent of average)
Sacramento Valley Index (SVI)
(50 percent exceedance)
San Joaquin Valley Index (SJI)
(75 percent exceedance)
Runoff: Unimpaired flows in Percent of Average for Water Year 2019
Hydrologic Region Oct
Sacramento River Region 78 56 45 53 San Joaquin River Region 65 56 43 50 Tulare Lake Region 65 55 51 55
Through the first 7-8 days of January, rivers in the Sierra Nevada are flowing well below average to start the month.
January full natural flow rates updated through January 7-8, 2019
River Basin Percent of Historic Average Trinity 26 Shasta Inflow 43 Sacramento at Bend Bridge 45 Feather 31 Yuba 25 American 27 Cosumnes 16 Mokelumne 26 Stanislaus 36 Tuolumne 31 Merced 24 San Joaquin 35 Kings 42 Kaweah 27 Tule 26 Kern 43
Precipitation: Precipitation for Water Year 2019 accumulated at the following rates of average
Region WY accumulated precipitation (%) through December 31, 2018 Sacramento River Valley 75 San Joaquin River Valley 99 Tulare Lake Basin 105 Statewide 84 Regional Precipitation Indices Average to date
as of January 9, 2019
Northern Sierra 8-Station Index 76 (16.2 inches) San Joaquin 5-Station Index 79 (12.1 inches) Tulare Basin 6-Station Index 94 ( 9.9 inches)
Monthly Precipitation to date in Percent of Average for Water Year 2019 for Regional Precipitation Indices
Regional Precipitation Indices Oct Nov Dec Jan Northern Sierra 8-Station Index 34 104 54 38 San Joaquin 5-Station Index 36 152 34 29 Tulare Basin 6-Station Index 125 163 40 31
The snowpack as of the morning of January 9, 2019 stands at the following (based on snow sensors)
Region Snow Water Equivalent (inches) % of Average (Apr 1) % of Average (Jan 9) Northern 10.8 38 87 Central 11.4 38 88 Southern 8.6 34 87 Statewide 10.4 37 88
Weather and Climate Outlooks:
The 6-day weather forecast predicts up to 2.0, 1.0, and 0.5 inches over the Northern, Central, and Southern Sierras, respectively. The bulk of the precipitation in the Sierras is expected today. The 6-day weather forecast also predicts up to 2.5 inches on North and Central Coasts with localized precipitation amounts up to 3.5 inches near Big Sur. Freezing levels will remain near 6,000-8,000 feet over the Northern Sierras and 7,000-9,000 feet over the Central and Southern Sierras over the next six days.
The NWS Climate Prediction Center (CPC) one‐month outlook for January, posted December 31, indicates increased chances of above normal temperatures for the entire State. The same outlook suggests increased chances of above normal precipitation for the southern third of the State.
The CPC three‐month (January‐February-March) outlook, posted December 20, indicates increased chances of above normal temperatures for the entire State. The same outlook suggests increased chances of below normal precipitation for the northern third of State and equal chances of above or below normal precipitation everywhere else excluding the southern border with Arizona where increased chances of above normal precipitation are expected.
According to the latest El Niño/Southern Oscillation (ENSO) discussion issued by the Climate Prediction Center on January 7, 2019, ENSO-neutral conditions are present. Equatorial sea surface temperatures are above average across most of the Pacific Ocean. The patterns of convection and winds are mostly near average over the tropical Pacific. El Niño is expected to form and continue through the Northern Hemisphere winter 2018-2019 (~90% chance) and through spring (~60% chance).
The next WSI forecast for conditions as of February 1, 2019 will be available on Friday, February 8. The first Bulletin 120 of the water year 2019 will also be issued at that time. If you have any questions regarding this forecast, please contact a member of the Snow Surveys staff.
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
- 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
- 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.noaa.gov/products/predictions/30day/
- Climate Prediction Center Three-Month Outlook Forecasts: http://www.cpc.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
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