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California-Nevada Drought and Climate Outlook Webinar: September 27, 2021

Event Date
September 27, 2021
Event Time
11:00 am - 12:00 pm

According to the September 9 U.S. Drought Monitor, 100% of California and Nevada are in drought, with 79.6% in Extreme (D3) or Exceptional (D4) Drought. Continued drying has enhanced wildfire risk throughout the region, reflected in several continuing very large wildfires in northern California. Further, forecasts increasingly reflect the potential for La Niña development in the fall and into the winter. Historically, La Niña is associated with dry to normal conditions in the southern part of California and Nevada.

The California-Nevada Drought Early Warning System September 2021 Drought & Climate Outlook Webinar is part of a series of regular drought and climate outlook webinars designed to provide stakeholders and other interested parties in the region with timely information on current drought status and impacts, as well as a preview of current and developing climatic events (i.e., El Niño and La Niña). 



Welcome to the California-Nevada Drought & Climate Outlook Webinar

Speaker: Amanda Sheffield, NOAA/National Integrated Drought Information System (NIDIS), Cooperative Institute for Research in Environmental Sciences (CIRES)



Drought and Climate Update and Outlook

Speaker: John Abatzoglou, University of California Merced

  • 38% of California-Nevada is in Exceptional Drought (D4) compared to <3% this time last year.
  • Record heat—in at least the last 125 years—is the story for summer 2021 in the California-Nevada region. Why? An incredibly dry spring led to drier soils and hotter temperatures through land atmosphere interactions + western dominant high pressure ridge over summer. 
  • Compound dry-hot conditions produced the “worst” single-year drought in Northern California per some indicators.
  • 2 years of drought back to back has intensified impacts, like low reservoirs and an active wildfire season in forested areas of California. 
  • A likely La Niña suggests a dry winter in the southern portion of the region and a “coin toss” in northern California.



California Groundwater Update

Speaker: Steven Springhorn, California Department of Water Resources

  • Groundwater acts as an important drought buffer and helps lessen the water supply impacts of our changing climate—groundwater provided nearly 60% of the state’s total water supply in 2015 during the peak of the 2012 to 2016 drought.
  • Approximately 82% of Californians—33 million people—rely on groundwater for some portion of their drinking water or other household uses, and nearly 6 million Californians are entirely dependent on groundwater for drinking water supplies.
  • There have been about 305,000 (~255,000 drinking water, ~50,000 irrigation wells) production well completion reports since 1977.
  • About 160 dry wells were reported in the last 30 days, and >700 year to date. 
  • Resources and new products coming in the next few weeks:



Nevada Groundwater Update

Speaker: Levi Kryder, Nevada Department of Water Resources

  • The State Engineer is responsible for the administration of Nevada’s groundwater.
  • Nevada has 256 administrative groundwater basins, generally defined by topographic features. Aquifer types: valley-fill alluvial, volcanic, carbonate rock.
  • Drought has varied impacts on Nevada’s groundwater resources dependent on aquifer type. Groundwater use helps buffer the effects of drought, but storage does not fully recover on a year-to-tear basis, and storage depletion increases with successive drought cycles. 
  • There are significant impacts related to groundwater/surface water connections and conflict between groundwater and surface water uses.



Autumn Rainfall Arrival and Wildfire Risk in Southern California

Speaker: Dan Cayan, California-Nevada Climate Applications Program (CNAP, a NOAA RISA Team), Scripps Institution of Oceanography

  • Santa Anas and autumn rains work in opposition.
  • This research focuses on NOAA region 6—South Coast California climate division—where wildfire problems often come in the fall. Autumn rainfall onset varies from year to year by greater than 30 days. The median onset date is November 10.
  • 9 times more acres are burned before vs. after onset (using data from 1948–2018). Most large wildfires occur during Santa Anas. 
  • Volatile onset of vital autumn precipitation. 
  • Information needed: monitoring, projects, forecasts.



Question & Answer




Speaker: Amanda Sheffield, NOAA/NIDIS, CIRES

  • Register now for the next webinar in this series on Monday, November 22, 2021.