California-Nevada Drought Status Update

December storms helped, but the drought is not busted yet.

Key Points

Several December storms have helped snowpack and soil moisture conditions; nonetheless, 98% of California and 100% of Nevada remain in drought.
A La Niña advisory is still in effect, but is expected to change to ENSO neutral by spring.
Extended range forecasts are leaning towards dry conditions for California and Nevada for the latter part of December. However, storms forecasted for the Pacific Northwest could drop down and impact the region.
A Colorado Basin 24-month study shows Lake Powell dropping below the power pool in the minimum probable inflow scenario.

U.S. Drought Monitor Conditions | December 13, 2022

U.S. Drought Monitor

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 December 13, 2022:

97.94% of California is experiencing Moderate (D1) to Exceptional (D4) Drought (28.33% in D3, 7.16% in D4)
California population in drought: 37,060,803
100% of Nevada is experiencing Moderate (D1) to Exceptional (D4) Drought (24.45% in D3, 0% in D4)
Nevada population in drought: 2,700,550

Source(s): NDMC, NOAA, USDA

U.S. Drought Monitor Categories

Last Updated: 12/13/22

98.79%

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

35.50%

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

24.45%

of Nevada is in extreme (D3) drought

Current Conditions

According to the U.S. Drought Monitor, over the last month drought conditions have improved slightly in a few areas in California and Nevada. Recent storms have built a snowpack well above average for this time of year and increased soil moisture throughout much of California and Nevada.
Much of southern and central California have received above-normal precipitation for this time of year while precipitation in northern California is currently below normal. Southern Nevada and northwestern Nevada have received below-normal precipitation, though parts of Nevada are well above normal.
A cold November that is continuing into December has helped to preserve the snowpack and minimize evaporative demand (the “thirst” of the atmosphere).
Although recent storms have produced a healthy snowpack for this time of year, the snowpack is about 50% of April 1 normal snow water equivalent values.
Western Sierra reservoirs’ water storage plus snowpack is near normal for this time of year due to the recent storms, but many major reservoirs in California are well below normal.
In Nevada, Lake Mead, Lake Tahoe, and Lake Lahontan are well below the average percent of capacity. For Lake Tahoe, when snowpack plus water storage are combined, the total storage is above the rim.
The most recent 24-month study for the Colorado River under the minimal probable inflow scenario shows Lake Powell dropping below the power pool and Lake Mead dropping to 1,018 feet.
The Metropolitan Water District’s Board of Directors has declared a Regional Drought Emergency for all of Southern California and called upon water agencies to immediately reduce their use of all imported supplies.
In the Upper Colorado, the combined snowpack and 20 upstream reservoirs of Lake Powell are slightly below normal for this time of year.
For more information, check out Living with Drought in Nevada and the California Water Watch.

How is drought affecting your neighborhood? Click to see drought indicators, outlooks, and historical conditions by city, county, and state, as well as sign up for alerts.

View local drought information

U.S. Drought Monitor 4-Week Change Map

From November 15 to December 13, 2022, select regions across California and Nevada have seen 1-category improvements in their U.S. Drought Monitor classification. The rest of the region has seen no change. — U.S. Drought Monitor 4-week change map, showing where drought has improved, degraded, or remained the same from November 15 to December 13, 2022). Source: National Drought Mitigation Center.

Percent of Normal Precipitation: Water Year to Date

Since October 1, Coastal California up towards San Francisco Bay along with north east Nevada show values above 110% of normal. Much of Northern California and Southeastern California and southern Nevada are below 70% of normal precipitation. — Percent of normal precipitation since the start of Water Year 2023 (October 1–December 12, 2022). Source: High Plains Regional Climate Center.

Average Daily Maximum/Minimum Temperature Percentiles

Almost all of Nevada and California are in the 33rd and below percentiles for average daily maximum temperature from October 14 to December 12. Much of The northern half of Nevada is below 10th percentile for average daily minimum temperature. — Average daily maximum temperature (*left*) and minimum temperature (*right*) shown as a percentile (based on 1979–2015) over the last 60 days (October 14–December 12, 2022) throughout California and Nevada. Source: Climate Toolbox.

Snow Water Equivalent Change: December 8–12

Change in snow water equivalent (inches) over the Sierra Nevada from December 8th to 12th. The change in SWE for individual stations ranges between a high of 8.5 inches and a low of 2.9 inches. — Five-day (December 8–12, 2022) change in snow water equivalent (inches). Source: California Nevada River Forecast Center.

Snow Water Equivalent Percent of Normal

Snow water equivalent at California and Nevada stations as percent of normal for this time of year. All stations in the Sierra Nevada are much above normal, ranging between 200% to 400% for this time of year.

Snow water equivalent at California and Nevada stations as percent of April 1st snowpack. Most stations in the Sierra Nevada are much below the April 1 normal, ranging between 39% and 77%. — The snow water equivalent (SWE) percent of normal for this time of year (*top*) and as a percent of April 1st snowpack (*bottom*) as of December 12, 2022. Source: California Nevada River Forecast Center.

Daily Averaged Soil Moisture Anomalies

Based on NASA SMAP satellite data, the highest elevations in the Sierra Nevada and far southeastern California are showing anonymously dry conditions ranging from 30% to 50% below normal. The rest of California is anonymously wet. Western Nevada is also anomalously wet with much of the rest of the state showing near normal or anomalously dry conditions. — Daily averaged soil moisture anomalies from December 11, 2022 based on NASA SMAP (Soil Moisture Active Passive) satellite data. Source: Crop Condition and Soil Moisture Analytics.

Depth Averaged Soil Saturation in Nevada and the Eastern Sierra

According to this time series of soil moisture in percent saturation for Nevada and the Eastern Sierra for Water Year 2023, the current value is 32.3% and the median for the period of record is about 40%. — Daily soil moisture over Nevada since the start of the water year (October 1, 2022) shown as percent saturation. The black line shows the current soil moisture for this water year, and there are statistical shading breaks at the 10th, 30th, 50th, 70th, and 90th percentiles. Source and for other stations: USDA National Resources Conservation Service (NRCS) National Climate and Water Center.

Water Storage + Snowpack: 28 Western Sierra Reservoirs and Lake Tahoe

Water storage (reservoir plus snowpack) is near normal for this time of year in the Western Sierra.

In the Lake Tahoe Basin, snowpack plus reservoir is about 50% of the combined reservoir and snowpack for this time of year. — Water storage, a combination of snowpack and reservoir storage, as of December 11, 2022, compared to the 2000–2015 normal in the Western Sierra (*top*) and compared to 1981–2010 normal for Lake Tahoe (*bottom*). Source: CNAP Water Storage Tracking.

Nevada Reservoir Storage

As of December 1, Lake Mead, Lake Tahoe, and Lake Lahontan are well below the average percent of capacity. — Summary of Nevada reservoir levels, as of December 1, 2022. The black outline indicates the average capacity as a percentage of total at each reservoir. The blue shading is the current capacity. Figure courtesy of S. McAfee, Nevada State Climatologist.

Upper Colorado River Basin Water Storage

Water storage tracking for the Upper Colorado River Basin, upstream of Lake Powell. The 2022-2023 (through 12/12/22) reservoir volume and reservoir + snowpack are about 45% of the April/May peak. — Water storage for the Upper Colorado, a combination of snowpack and 20 upstream reservoirs, compared to 1989–2018 normal as of early December 12, 2022. Green lines show current (*thick line*) and normal (*thin line*) Lake Powell plus 20 upstream reservoir storage. Red lines show current storage for 20 upstream reservoirs (*thick line*) and reservoirs + snowpack (*thin line*). Source: CNAP Water Storage Tracking.

Drought & Climate Outlook

El Niño–Southern Oscillation (ENSO)

NOAA’s ENSO alert system status is currently a La Niña Advisory. La Niña is expected to continue into the winter, with equal chances of La Niña and ENSO-neutral during January–March 2023. In February–April 2023, there is a 71% chance of ENSO-neutral. For more information, check out the NOAA ENSO blog or current status presentation and how La Niña impacts the Western U.S.

Subseasonal to Seasonal Drought, Temperature, and Precipitation Outlooks

The next one-to-three month forecast shows drought persisting across California and the Great Basin, given the La Niña advisory. Historically, La Niña is associated with dry to normal conditions in the southern part of California and Nevada. The January-February-March outlook from the National Weather Service's Climate Prediction Center also favors equal chances of above- or below-normal temperatures for much of the region, with above-normal temperatures in southern California and Nevada. In the near term (1–2 weeks), both GEFS (the U.S. national model) and ECMWF (the European model) are suggesting another storm around December 22–23 focused on Oregon, but it may impact northern California and Nevada.

Seasonal (3-Month) Drought Outlook

From December 15 to March 31, drought is predicted to persist or develop across California and Nevada. — U.S. seasonal drought outlook, showing where drought is forecasted to persist, improve, be removed, or develop from December 15, 2022 to March 31, 2023. Source: NOAA's Climate Prediction Center.

Seasonal Temperature and Precipitation Outlooks

From January to March 2023, odds slightly favor above-normal temperatures in southern California and Nevada, and below-normal temperatures in far-northern California along the Oregon border.

From January to March 2023, odds favor below-normal precipitation in central/southern California and southern Nevada, with equal chances of above- or below-normal precipitation in the rest of the region. — U.S. seasonal temperature (*top*) and precipitation (*bottom*) outlooks, showing the likelihood of above- or below-normal conditions for January–March 2023. Source: NOAA's Climate Prediction Center.

Likelihood and Timing of Atmospheric River Conditions

The Global Ensemble Forecast System (GEFS) predicts a storm around December 22–23, impacting Oregn. — The CW3E Atmospheric River (AR) Landfall Tool displays the likelihood and timing of AR conditions (here IVT>250 kg/(ms)) 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. Source: Center for Western Weather and Water Extremes (CW3E).

Drought Early Warning Resources

California

Nevada

California-Nevada DEWS

Prepared By

Julie Kalansky
Program Manager, California-Nevada Adaptation Program (A NOAA CAP/RISA team)

Special Thanks

This drought status update is issued in partnership between the National Oceanic and Atmospheric Administration (NOAA), the California-Nevada Adaptation Program (a NOAA CAP/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 status updates as conditions evolve.