California-Nevada Drought Status Update

A Wet December: Drought buster, false hope, or somewhere in between?

Key Points

December storms brought more than 200% of normal precipitation to a large area of California and Nevada. In the Sierra Nevada, much of this fell as snow.
Recent storms improved the drought status by 1–2 categories, according to the U.S. Drought Monitor, throughout much of the region. Combined snow plus reservoir levels are near normal or above in the Southern Sierra for this time of year, but still below normal in the Northern Sierra.
Extended range forecasts for January indicate the next two weeks will have below-normal precipitation. January and February precipitation is critical in determining if the December storms are the beginning to the end of the drought (i.e., stormy pattern returns by late January) or will help mitigate the impacts of the ongoing drought, but not end it (i.e., extended dry pattern continues in February).

U.S. Drought Monitor Conditions | January 4, 2021

California-Nevada

The U.S. Drought Monitor (USDM) is updated each Thursday to show the location and intensity of drought across the country. Drought categories show experts’ assessments of conditions related to dryness and drought including observations of how much water is available in streams, lakes, and soils compared to usual for the same time of year.

California/Nevada conditions as of January 4, 2022:

99.3% of California is experiencing Moderate (D1) to Exceptional (D4) Drought (15.76% in D3, 0.84% in D4)
California population in drought: 37,223,546
100% of Nevada is experiencing Moderate (D1) to Exceptional (D4) Drought (16.71% in D3, 7.5% in D4)
Nevada population in drought: 2,700,551

Source(s): NDMC, NOAA, USDA

U.S. Drought Monitor Categories

Last Updated: 01/04/22

99.59%

of California and Nevada are in drought (D1–D4)

16.60%

of California is in extreme to exceptional (D3–D4) drought

24.21%

of Nevada is in extreme to exceptional (D3–D4) drought

Current Conditions

According to the U.S. Drought Monitor, since the start of the water year (Oct. 1, 2021) drought in California-Nevada has improved 1–2 categories across much of the region with a 3-category improvement over Ventura County, California. California is no longer 100% in drought.
Most of the region has received over 100% of normal precipitation for this time of year. The exceptions are in southeastern California and southern Nevada.
Late December storms increased snowpack significantly. California went from 25% of April 1 normal snow water equivalent (SWE) on December 20 to 57% on January 5. Similarly, the Upper Humboldt SWE increased by 4.1 inches.
Water storage, represented here as reservoir plus snowpack, in the Southern Sierra is above normal for this time of year and near normal for the Central Sierra and Lake Tahoe. Northern Sierra water storage remains below normal.
The odds of reaching water year normal precipitation, as of January 1, have increased to 70% or above for much of the region, with the exception of much lower odds in southern Nevada and southeast California. The large deficit from last year makes the odds of combined 2021–2022 Water Years reaching a two-year normal (bottom right) less than 10% for almost the entire region.

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U.S. Drought Monitor Change Map: October 5–January 4

U.S. Drought Monitor Change Map for California and Nevada, showing the change in drought conditions from October 5, 2021 to January 4, 2022. Much of the region saw a 1-2 category improvement, with a 3 category improvement over Ventura County, CA. — U.S. Drought Monitor change map, showing how drought has degraded or improved in the past 13 weeks, from October 5, 2021 to January 4, 2022. Source: National Drought Mitigation Center.

Percent of Normal Precipitation: Water Year to Date

The image shows the percent of normal precipitation for California and Nevada over 10/1/2021 - 1/4/2022. Southeast California and Nevada remain with less than normal precipitation, but the rest of California and Nevada show normal precipitation. — Percent of normal precipitation since the start of Water Year 2022 (October 1, 2021–January 4, 2022). Source: High Plains Regional Climate Center.

Percent of Normal Precipitation: Last 14 Days

The image shows the percent of normal precipitation for California and Nevada over 12/22/2021 - 1/4/2022. Much of California and Northern Nevada show above 400% of normal precipitation during this period. — Percent of normal precipitation over the past 14 days (December 22, 2021–January 4, 2022). Source: High Plains Regional Climate Center.

Snow Water Equivalent in the Sierra Nevada Region: December 20 vs. January 5

A topographic map showing the three major watersheds in the Sierra, Northern Sierra/Trinity (grey shading), Central Sierra (red shading) and Southern Sierra (green shading). The text shows the percent of the April 1st normal in black and the percent of normal for this time of year for each of the three regions. California was at 26% of the April 1 normal on December 20, 2021.

Upper Humboldt Snow Water Equivalent

Time series graphic showing snow water equivalent (SWE) in inches (Y-Axis) for October 1, 2021 through September 30, 2022 (X-axis) for the Upper Humboldt water basin. The current percent of median is 119%, percent of median peak is 43%, and days until median peak is 88. — Current snow water equivalent status of the Humboldt watershed in inches. See more watersheds and stations at the Natural Resource Conservation Service.

Reservoir Storage + Snowpack: WY 2021–2022

A time series graphics showing water storage tracking (reservoirs + snow pack) in millions of acre-feet (Y-Axis) for Oct 1, 2021 thru Oct 1, 2022 (X-axis) for Lake Tahoe. The reservoir normal peaks near May-June for Lake Tahoe. — Water storage, a combination of snowpack and reservoir, compared to the 2000–2015 normal in the Northern, Central, and Southern Sierra, and compared to the 1981–2010 normal at Lake Tahoe, as of January 5, 2022. Source: CNAP Water Storage Tracking.

Odds of Reaching Water Year Normal Precipitation

Three maps, showing the odds of WY 22 reaching 100% of normal water year precipitation as of January 1, 2022 (left) and December 1, 2021 (top right). The map in the bottom right shows the odds of reaching normal a two year normal precipitation starting in October 2020. Most of California and Nevada have 70%-100% odds of reaching 100% of normal precipitation except for Southern Nevada which has about 30% odds of reaching normal. Most of California and Nevada have less than 30% odds of reaching a two year period of normal precipitation. — The odds of reaching water year normal precipitation based on historical water year totals. As of January 1, 2022, much of the region has 70%-100% odd of reaching water year normal precipitation in WY 2022. This is a large increase from December 1, 2021 (*upper right*). The large deficit from last year makes the odds of reaching a two-year normal (*bottom right*) less than 10% for almost the entire region. Learn more about this product at CW3E website.

Recent Drought Impacts

Find additional impacts through the National Drought Mitigation Center’s Drought Impact Reporter.
January 4: The California State Water Resources Control Board imposed new drought rules for water use within 48 hours of rainfall. The rules will be in place for one year.
January 4: Lake Oroville’s Hyatt Powerplant began operating again as reservoir levels rose. The powerplant was shut down on August 5.
The California Department of Fish and Wildlife estimated only 2.6% of the winter-run Chinook salmon juvenile populations survived the hot, dry summer.
December 23: The California Department of Water Resources awarded more than $53 million in urban and multi-benefit drought relief funding.
December 20: The U.S. Bureau of Reclamation funding plan includes $61.8 million to the Central Valley Project to address ongoing drought needs.
December 15: Water leaders in Arizona, Nevada, and California signed an agreement at the Colorado River Water Users Association to voluntarily reduce their take from the Colorado River.

Report Your Drought Impacts

Drought & Climate Outlook

El Niño–Southern Oscillation (ENSO)

NOAA’s ENSO alert system status is currently a La Niña Advisory. La Niña is favored to continue through the Northern Hemisphere winter 2021–22 (~95% chance) and transition to ENSO-neutral during the spring 2022 (~60% chance during April–June). For more information, please check out the NOAA ENSO blog.

Subseasonal to Seasonal Drought, Temperature, and Precipitation Outlooks

The next three months’ forecasts show drought persisting across Nevada and remaining but improving over much of California, with removal likely in the south coast. Changes were introduced for California and Nevada in the seasonal drought outlook at the end of December due to a wet pattern during late December across the western contiguous U.S., favoring improvement. Modifications included depicting improvement (D2–D4 areas) and removal (D1 areas) across parts of the Great Basin, Southwest, and California.

According to the National Weather Service's Climate Prediction Center (CPC), during the first three months of 2022 (January-February-March), the pattern across North America is likely to be strongly influenced by ongoing La Niña conditions, which typically favor an active weather pattern and below-normal temperatures across the Pacific Northwest, northern California, northwest Nevada, and north-central CONUS, as well as abnormally dry, warm conditions across the southern tier of states. The CPC January and January-February-March temperature and precipitation outlooks broadly reflect this signal, with a potential for below-normal precipitation in southern California and southern Nevada with equals chances of above- or below-normal precipitation for the rest of the region (except for small area along the northern California and Nevada borders that slightly favors above-normal precipitation). Therefore, due to the current conditions combined with seasonal outlooks, drought improvement is favored for much of coastal central and northern California and the Sierra Nevada, while persistence is maintained across the San Joaquin Valley, which relies more on spring snowmelt for moisture. In the near term, a weaker system is expected later this week to impact northern California and Nevada, followed by a lull in storminess as a high pressure system is established in the eastern Pacific.

Seasonal Drought Outlook: January 1–March 31, 2022

Climate Prediction Center seasonal drought outlook, showing the probability drought conditions persisting, improving, developing, or being removed across the U.S. from January 1, 2022 to March 31, 2022. — U.S. Seasonal Drought Outlook for January 1 to March 31, 2022, showing the likelihood that drought will develop, remain, improve, or be removed. Source: NOAA Climate Prediction Center.

Temperature and Precipitation Outlooks: January 2022

Climate Prediction Center 1-month temperature outlook for the U.S., valid for January 2022. Odds favor below-normal temperatures for northern California into northwestern Nevada, with equal chances elsewhere.

Climate Prediction Center 1-month precipitation outlook for the U.S., valid for January 2022. Odds favor below-normal precipitation in southern California and southern Nevada, with slight chances of above-normal precipitation near the northern borders of both states. — January 2022 temperature outlook (*top*) and precipitation outlook (*bottom*), showing the probability (percent chance) of above-normal, below-normal, and near-normal conditions. Source: NOAA Climate Prediction Center. How do I interpret these graphics?

Likelihood and Timing of Atmospheric River Conditions

Two figures show the probability of atmospheric rivers by (left) forecast day (x-axis) (from January 6, 2022) and latitude (y-axis) and (right) longitude (x-axis) and latitude (y-axis). Shows shows near term potential for an AR impacting the PNW, a lull, and then potential for more ARs impacting the west in the coming weeks. — The CW3E Atmospheric River (AR) Landfall Tool displays the likelihood and timing of AR conditions (here IVT>250 kg/(ms)) from January 6, 2022 at each point on the map in a line along the West Coast of North America or inland derived from either the NCEP Global Ensemble Forecast System or the ECMWF Ensemble Prediction System.

Drought Early Warning Resources

California

Nevada

California-Nevada DEWS

Prepared By

Amanda Sheffield
California-Nevada DEWS Regional Drought Information Coordinator, NOAA/NIDIS, CIRES
Email: amanda.sheffield@noaa.gov

Julie Kalansky
Program Manager, California-Nevada Climate Applications Program (a NOAA RISA team)
Email: jkalansky@ucsd.edu

Special Thanks

This drought status update is issued in partnership between the National Oceanic and Atmospheric Administration (NOAA), the California-Nevada Applications Program, a NOAA RISA team, and the Western Regional Climate Center at the Desert Research Institute to communicate the current state of drought conditions in California-Nevada based on recent conditions and the upcoming forecast. NIDIS and its partners will issue future drought updates as conditions evolve.