WATER SUPPLY INDEX FORECAST for January 1, 2020

From the Department of Water Resources:

Welcome everyone to a 2nd New Year, “The Calendar New Year”. This is the time most everyone else starts living the New Year, since their New Year does not start October 1.  Cheers!!

Forecast Summary:

A Water Year 2020 Water Supply Index (WSI) forecast for conditions as of January 1, 2020 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 31, 2019 and can be summarized as follows:

Sacramento River Unimpaired Runoff Water Year Forecast

(50 percent exceedance)

14.3

(80 percent of average)

Sacramento Valley Index (SVI)

(50 percent exceedance)

7.6

(Below Normal)

San Joaquin Valley Index (SJI)

(75 percent exceedance)

2.7

(Below Normal)

Runoff: Unimpaired flows in Percent of Average for Water Year 2020
  Oct

Runoff

Nov

Runoff

Dec

Runoff

Oct-Dec

Runoff

 
Sacramento Valley Index (4 rivers) 89 45 74 68
San Joaquin Valley Index (6 rivers) 92 33 84 70
Tulare Lake Basin (4 rivers) 110 77 91 91

 

Precipitation: Cumulative Precipitation in Percent of Average for Water Year 2020
Regional Precipitation Indices As of January 8, 2019
Northern Sierra 8-Station Index 62 (13.1  inches)
San Joaquin 5-Station Index 64 (9.8 inches)
Tulare Basin 6-Station Index 71 (7.4 inches)

 

Monthly Precipitation in Percent of Average for Water Year 2020 for Regional Precipitation Indices
Regional Precipitation Indices Oct Nov Dec Jan (8)
Northern Sierra 8-Station Index 3 43 106 2
San Joaquin 5-Station Index 0 69 104 0
Tulare Basin 6-Station Index 0 106 89 0
Snowpack: The snowpack as of the morning of January 8, 2020 stands at the following (based on snow sensors)
Region Snow Water Equivalent (inches) % of Average (Apr 1) % of Average (Jan 8)
Northern 8.8 30 70
Central 10.1 34 80
Southern 9.0 35 92
Statewide 9.4 33 80

 

Weather and Climate Outlooks:

According to the CNRFC 6-day forecast, a series of storms are expected to bring needed precipitation to the state over the next 6 days. The Klamath basin and the north coast are expected to receive up to 2 inches of precipitation over the next 6 days. The Upper Sacramento, Feather, Yuba, and American basins are expected to receive approximately 1 inch of precipitation over the same period. The San Joaquin and Tulare basins are expected to receive modest amounts of precipitation of approximately 0.6 and 0.2 inches, respectively, over the next 6 days. Freezing elevations across the state are anticipated to be low for the next 6 days. The elevations generally range from 3,000 to 5,000 feet as we move from the California-Oregon border to Southern California. The only exception is Friday when the elevations increase by 2,000 feet on average, all across the state.

The NWS Climate Prediction Center (CPC) one‐month outlook for January 2020, issued on December 31, 2019, points to equal chances of above or below normal temperatures for the northern half of the state and chances of below normal temperature for the southern half of the state. The same outlook suggests equal chances of above or below normal precipitation for the entire state.

The CPC three‐month (January‐February-March) outlook, issued on December 19, 2019, points to chances of above normal temperatures for the entire state. The outlook has not changed since last month. The same outlook suggests equal chances of above or below normal precipitation for the northern half of the state and chances of below normal precipitation for the southern half of the state.

According to the latest El Niño/Southern Oscillation (ENSO) discussion issued by the Climate Prediction Center on January 6, 2020, ENSO-neutral conditions are present. Equatorial sea surface temperatures are near-to-above average across the Pacific Ocean. ENSO-neutral is favored during the Northern Hemisphere winter 2019-20 (70% chance), continuing through spring 2020 (~65% chance).

Next Update:

The next WSI forecast for conditions as of February 1, 2020 will be available on February 10. The first Bulletin 120 (B120) forecast of the new water year will be available on the same date.  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:

Precipitation Data:

Snow Data:

Extended Regional Forecasts:

 

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