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Regional Drought Update Date
March 11, 2021
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Drought Status Update

Drought Status Update for California-Nevada


DEWS Regions:
States:
Update Status:

NIDIS and its partners will issue future drought updates as conditions evolve.

Drought Preparedness Key as Continuing Drought Conditions and Impacts Compounded By Back-to-Back Dry Years.

Key Points

  • California and Nevada remain entrenched in moderate-to-exceptional drought as the fifth into sixth consecutive dry months since October, likely ensuring that the region will suffer back-to-back dry water years.
  • In California, 91% of the state is in drought, according to the U.S. Drought Monitor. In Nevada, 100% of the state is in drought, and 40% is in exceptional drought (D4), more area than at any point during the 2012-2016 drought. 
  • Precipitation totals and snowpack remain well below normal. Since the North Pacific storm season is nearing its usual demise, the amount of additional precipitation that can be expected is most likely too small to reverse drought conditions, especially in the most intense drought regions. 
  • Drought impacts (e.g., pasture conditions, ecosystem health, water supply, fire potential) will likely intensify and expand given back-to-back dry years. Drought preparedness is key.
Current Conditions
U.S. Drought Monitor Conditions: California-Nevada | March 9, 2021

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 March 9, 2021:

  • 91% of California is experiencing Moderate (D1) to Exceptional (D4) Drought (26% in D3, 3.75% in D4)
  • California population in drought: 32,944,045
  • 100% of Nevada is experiencing Moderate (D1) to Exceptional (D4) Drought (32% in D3, 40% in D4)
  • Nevada population in drought: 2,700,553

U.S. Drought Monitor Categories

The color with the hex code #ffff00 identifies:
D0
The color with the hex code #ffcc99 identifies:
D1
The color with the hex code #ff6600 identifies:
D2
The color with the hex code #ff0000 identifies:
D3
The color with the hex code #660000 identifies:
D4
Main Stats
91%
of California is experiencing Moderate to Exceptional Drought (D1-D4)
100%
of Nevada is experiencing Moderate to Exceptional Drought (D1-D4)
40%
of Nevada is experiencing Exceptional Drought (D4)

Current Conditions

  • According to the U.S. Drought Monitor, drought conditions over the past 2 weeks have expanded in coastal California and deteriorated over the Sierra crest. Nevada remains 100% in drought and currently has more area in exceptional drought (D4) than at any point during the 2012-2016 drought (see U.S. Drought Monitor time series here). 
  • Recent storms brought 0.5-2 inches of precipitation to Northern and Southern California, though this remains below normal for the region. 
  • Recent storms are not enough to ameliorate most drought conditions and long-term drought. Since the start of Water Year 2020 (October 1, 2019), much of Nevada and Northern California are missing between 1-1.75 years of precipitation.  
  • On March 2, the California Department of Water Resources conducted the third manual snow survey of the season at Phillips StationStatewide snow survey measurements continue to reflect the overall dry conditions with statewide snow water equivalent at 15.5 inches, or 58% of the March 11 average, and 55% of the April 1 average. 
  • Storage in the largest northern California reservoirs is well below average, reflecting cumulative impacts from a dry 2020. Virtually all the state remains in a precipitation deficit. (Water Year 2021: The Suspense Continues)
  • Reservoir storage in Nevada is lower than it was this time last year. In the Carson, Truckee, and Walker basins, the storage is less than 40% of capacity. 
  • The historical odds of reaching normal precipitation this water year are 10% or less in many places throughout California and Nevada. The odds of reaching 75% of normal precipitation are 30% or less in much of California and Southern Nevada. Looking back at precipitation records since 1948, not one “miracle March” would be enough to bring the worst-off areas in California and Nevada up to normal this year. Northern Nevada has the highest odds of reaching 75% of normal precipitation this water year. 
  • Evaporative demand (the atmospheric thirst that drives evapotranspiration) remains high as it has been throughout this water year, and vegetation is showing stress.

How is drought affecting your neighborhood?

Click to see drought indicators, outlooks, and historical conditions by city, county, and state, and to sign up for U.S. Drought Monitor alert emails.

Percent of Normal Precipitation: Last 14 Days vs. Water Year to Date

Two images show the percent of normal precipitation for California and Nevada through 3/10/2021. For the past 14 days (left image), CA-NV has been extremely below normal precipitation, continuing the trend since the start of the water year (right image).
Percent of normal precipitation for the last 14 days (left) and since the start of water year (right). Valid through March 10, 2021. Source: High Plains Regional Climate Center.

Years of Normal Precipitation to Reach 2-Year Normal

A map of California and Nevada shows water deficit as a fraction of normal water year’s precipitation. Much of the region is greater than 0.75 years with the exception of parts of southern California.
The fraction of a normal water year’s precipitation that is needed to compensate for the water deficit since October 1, 2019, as of March 9, 2021 based on PRISM data. Figure provided by C. Castellano, CW3E

Snow Water Equivalent Percent of Median: March 10, 2021

A map of the western U.S. showing the percent of 1981-2020 median snow water equivalent (SWE) values from the NRCS from 3/10/2021.  SWE in the Sierras is primarily between 60% and 70%.
Snow water equivalent percent of 1980-2010 median as of March 10, 2021. For an interactive version of this map, please visit the Natural Resources Conservation Service.

Water Storage in the Western Sierra Nevada 

Time series showing water storage tracking (reservoirs + snow pack) for October 1, 2020 through October 1, 2021 for the 28 Western Sierra reservoirs.   In the Western Sierra, reservoir normals are below normal and reservoir+snowpack are well below normal.
CNAP Water Storage Tracking comparing current below-normal reservoir and snowpack in the Western Sierra Nevada to 1981-2010 normals through March 8, 2021.

Nevada Reservoir Storage: Percent Capacity in 2020 vs. 2021

Bar graph of reservoir storage by percentage of capacity by basin in Nevada. All basins are showing percent capacity less than last year with the exception of Southern Nevada.
Reservoir storage in Nevada by basin. The bar graph shows the percent of the capacity that is filled in the previous year (green) and the current year (blue) as of March 1. Source: NRCS Water Supply Outlook Report.

Odds of Reaching Water Year Normal Precipitation for the West

Two maps of the western United States show the odds of reaching 75% (left image) and 100% (right image) of water year normal precipitation as of March 1, 2021 based on the historical record. Most of the west has a <40% chance of 100% normal, except for parts of the PNW including Montana. Most of California, southern NV, and western UT/AZ, have <50% chance of 75% of normal.
Odds of reaching 75% (left) and 100% (right) of normal water year precipitation as of March 1 throughout the West. Source: CW3E.

Evaporative Demand (ETo) Anomalies for the West

Water year to March 1, 2021 evaporative demand (ETo) anomalies for the Western U.S. Much of the western U.S. (especially the southwestern U.S.) is 1-4 standard deviations above normal.
Evaporative demand (or ETo, the atmospheric thirst driving evapotranspiration) anomalies throughout the West for the first five months of the 2021 water year (October, November, December, January, February) shown in standard deviations from normal. Figure provided by M. Dettinger.

Vegetation Drought Response Index (VegDRI)

A CONUS map of the Vegetation Drought Index (VegDRI) for 3/7/2021. Areas where the vegetation conditions are in moderate to extreme drought are found in CA, NV, AZ, NM, ID, OR, WA and TX.
Vegetation Drought Response Index (VegDRI) conditions from March 7, 2021.  

Drought Impacts

  • Current conditions continue to intensify and expand drought impacts, and as we head into summer, agriculture, water supplies, and ecosystems are likely to be impacted. Example state drought impacts based on past drought conditions provided by the National Drought Mitigation Center are available on the Drought.gov state webpages: California, Nevada.
  • The current California State Water Project (SWP)­ allocation of 10% amounts to 422,848 acre-feet of water, distributed among the 29 long-term SWP contractors who serve more than 27 million Californians and 750,000 acres of farmland. 
  • The U.S. Bureau of Reclamation announced low initial Central Valley Project (CVP) water supply allocation for contractors that reflect drier than average winter conditions combined with lower reservoir storage for the year. While the low allocations were not a surprise, multiple water agencies expressed disappointment in the announcement (AgNet). Groundwater is expected to be used to fill gaps.
  • Multiple media outlets are reporting that local water agencies and irrigation districts are considering drought actions, like conservation, after back-to-back dry years.
  • As winter rangeland grasses are limited, ranchers are reporting feeding and/or selling stock. Some permanent crops, such as orchards, are being irrigated earlier than normal.
  • Potential for wildfire entering into the summer season is expected to increase above 3,000 feet due to low snowpack. Low-elevation (below 3,000 feet) grasses are less likely to be an issue this year due to limited fine-fuel growth with back-to-back drought years, but this may change dependent on March-April precipitation. 

Report Your Drought Impacts

Drought & Climate Outlook

ENSO

NOAA’s ENSO alert system status is currently a La Niña advisory with moderate La Niña conditions over the equatorial Pacific. There is a ~60% chance of a transition from La Niña to ENSO-Neutral during the Northern Hemisphere spring 2021 (April-June). For more information, please check out the NOAA ENSO blog and the Western Regional Climate Center handout about the La Niña impacts for the west.  

Monthly Drought Outlook

Precipitation forecasts continue to show the influence of La Niña, and much of California-Nevada currently entrenched in moderate-to-exceptional drought is forecasted to continue. The next seasonal drought, temperature, and precipitation outlooks will be released March 18th.

Climate Predication Center Monthly Drought Outlook for March 2021, predicting the probability that drought will emerge, stay the same, or get better. Drought is likely to persist through most of California and Nevada.
U.S. Monthly Drought Outlook for March 2021. Source: NOAA Climate Prediction Center.

Temperature & Precipitation Outlooks

The moderate La Niña event is expected to slowly relax over the next few months, but in the meantime its influence on the nation's weather remains. The NOAA National Weather Service Climate Prediction Center's short-term to seasonal forecasts favor predominantly continuing warm, dry conditions, especially over the Great Basin and U.S. Southwest.   

Climate Prediction Center precipitation outlook for March to May 2021. Odds favor below-normal precipitation across all but northern California and Nevada.

Climate Prediction Center temperature outlook for March to May 2021. Odds favor above-normal temperature for most of California and Nevada, except Northern California and Northwestern Nevada.
March through May 2021 precipitation outlook (top) and temperature outlook (bottom). A = chances of above-normal; EC = equal chances of above, below, normal; B = chances of below-normal. Source: NOAA Climate Prediction CenterHow do I interpret these graphics? 

Drought Early Warning Resources

California     Nevada     California-Nevada DEWS

Prepared By

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

Julie Kalansky
Program Manager, California-Nevada Applications Program (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. 

Register here for the next California-Nevada Drought & Climate Outlook webinar on Monday, March 22 at 11 am PT.