Drought Status Update for California-Nevada

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 Station. Statewide 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

Years of Normal Precipitation to Reach 2-Year Normal

Snow Water Equivalent Percent of Median: March 10, 2021

Water Storage in the Western Sierra Nevada 

Nevada Reservoir Storage: Percent Capacity in 2020 vs. 2021

Odds of Reaching Water Year Normal Precipitation for the West

Evaporative Demand (ETo) Anomalies for the West

Vegetation Drought Response Index (VegDRI)

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.

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.   

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