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About the California DEWS

map of California

As NIDIS works to improve national drought resiliency, several regional Drought Early Warning Systems (DEWS) were formed to pilot innovations, resources, and lessons to be transferred to a National Early Warning System. The California DEWS began in 2010 as California was on the cusp of its current historic, ongoing drought.

California’s climate is a combination of a distinct dry season (mid-May to Late September/Early October) with a wet winter season defined by a few large precipitation events. Topography creates a diverse set of climates across California, from the snow peaks of the Sierra Nevada mountains to the Southern Californian deserts. California has adapted to this natural wet-dry seasonality through a well-plumbed reservoir system.

Drought in California is unique as meteorological, hydrological, and ecological factors vary with time and location, as do impacts within California’s complex economy and society. The California DEWS is developing and demonstrating a variety of early warning information resources and strategies, in partnership with agencies, industries, institutions, tribes, and other major stakeholders to build capacity for better decision making for drought planning and mitigation. Many projects are underway, including focus regions with distinct drought settings (urban, agricultural, tribal, environmental).

  • DEWS Activities and Resources to Support Drought Early Warning
  • Past Meetings & Workshops
  • Key Partners

DEWS Activities and Resources to Support Drought Early Warning

sample map of precipitation required to end level 2 drought for U.S. lower 48, from Sept 2016Drought Amelioration Product Suite: Determining how much rain and snow must fall to end a current drought and return the system to normal is a multi-faceted challenge, yet it is a question routinely asked, owing to the far-reaching societal and economic impacts of drought.  In 2016 and 2017, NOAA's National Centers for Environmental Information (NCEI) are revising and updating their drought amelioration product suite following guidance from their stakeholders.  These revisions include production of drought termination outlooks, upgrading current graphics to include regional perspectives, and promoting the delivery of these new products through established channels such as the California-Nevada DEWS program.  The goal of this effort is to provide reasonable support information that facilitates state and local water management and information to aid media interaction and communication with the public. See NCEI’s interactive maps, showing different timescales for the amount of precipitation needed to end or ameliorate a drought, the likelihood that that would occur.

Determining the Extent of Fallowed Land with Satellite Imagery in the CA Central Valley: A NIDIS partnership with USGS, NASA, USDA, and the California Department of Water Resources (CADWR)  demonstrated the feasibility of using satellite imagery to track the extent of fallowed land for drought impact reporting in the California’s Central Valley on a monthly basis. The assessment was completed in 2015 over the Central Valley and the California DWR plans to operationalize the fallowed land monitoring service for drought impact reporting as part of the California DEWS.

The California-Nevada Climate Adaptations Program, a NOAA RISA team (CNAP) and the Sonoma County Water Agency are collaborating to better understand the Russian River Valley’s future risk to drought and make the region more resilient to droughts. The project has three main tasks: (1) Understand how extreme precipitation events, atmospheric rivers (ARs) will change in the future and their role in ending droughts (2) Produce extreme drought scenarios to understand how the urban and natural landscapes will respond (3) Working with stakeholders to understand drought mitigation measures that are currently being executed and what can be done to make the area more resilient to drought in the future. CNAP and Sonoma County Water Agency are planning a future workshop with land managers to discuss the results of the drought scenarios and receive feedback on potential mitigation measures.

Forecast-Informed Reservoir Operations (FIRO) is a is a proposed management strategy that uses data from watershed monitoring and modern weather and water forecasting to help water managers selectively retain or release water from reservoirs in a manner that reflects current and forecasted conditions. FIRO is being developed and tested as a collaborative effort focused on Lake Mendocino that engages experts in civil engineering, hydrology, meteorology, biology, economics and climate from several federal, state and local agencies, universities and others including but not limited to: NOAA, US Army Corps of Engineers, USGS, CA Department of Water Resources, Sonoma County Water Agency and the Center for Western Weather and Water Extremes and Scripps Institution of Oceanography at UC San Diego.

Precipitation Percentiles: Researchers from the California-Nevada Climate Application Program (CNAP) have designed operationally practical drought indicators to assist California and Nevada stakeholders with their drought related decision-making needs. The drought indicators can be accessed in real-time via

Climate Outcome Likelihood Tool: As the length of time in drought continues, information on the likelihood of recovering from a long-term precipitation deficit has been in demand by stakeholders. In collaboration with NOAA's Western Regional Climate Center (WRCC), the California-Nevada Climate Applications Program (CNAP) and CA DWR have developed a Climate Outcome Likelihood tool
 specific to locations in California that lets stakeholders experiment to answer the question of what is the probability of reaching some threshold of precipitation.

SECURE Water Act Report – Reclamation Climate Change and Water 2016: The Department of Interior (DOI), the Bureau of Reclamation and its state and local partners developed a basin-by-basin report that characterizes the impacts of climate change and details adaptation strategies to better protect major river basins in the West. The report shows several increased risks to western U.S. water resources in the 21st century including specific chapters on the Sacramento/San Joaquin and Klamath River Basins.

Recognizing Anthropogenic Drought: As a follow-up to the 2015 American Geophysical Union (AGU) Chapman on California’s Drought in Irvine, CA, researchers from NOAA’s Office of Oceanic and Atmospheric Research (OAR) and the University of California system published an essay in Nature discussing the future implications for California (and other regions with growing populations and industries) facing increasing stress on its local and regional water supply for human and environmental needs.

Past Meetings & Workshops

“What's Ahead for California in 2016?”  In January of 2016, CNAP hosted two meetings to update California stakeholders on current conditions and climate outlooks with a specific focus on El Niño water supplies.

Southern California Stakeholders Meeting (July 7, 2015 at Scripps Institution of Oceanography in La Jolla, CA): CNAP hosted a meeting with the goal of better understanding  impacts of drought in the region and what different sectors are doing to mitigate those impacts; present and receive feedback on new drought tools; and determine the best steps forward for the S. California NIDIS community.

Ranching and California's Drought (November 7, 2014 at UC Davis):  NIDIS, the National Drought Mitigation Center (NDMC) and UC Davis hosted a workshop (and simultaneous webcast) for California farmers and ranchers to explore how the U.S. Drought Monitor (USDM) is developed and updated weekly and how local experts knowledge, real time ranch impacts and other relevant data can but used to inform the USDM. Speakers included USDM authors and the California State Climatologist. Ranchers and farmers shared perceptions and experiences with drought, new livestock feeding strategies during drought, and seasonal weather forecasts for California.