California-Nevada Drought & Climate Outlook Webinar: September 23, 2024

Welcome to the September California-Nevada Drought & Climate Outlook Webinar

Speaker: Amanda Sheffield | California-Nevada Regional Drought Information Coordinator, Cooperative Institute for Research in Environmental Sciences (CIRES), NOAA’s National Integrated Drought Information System (NIDIS)

• Welcome to the September California-Nevada Drought & Climate Outlook webinar. 
• Sign up for NIDIS emails as well as drought alerts.
• Sign up for the first webinar of the five-part 2024–2025 National Ecological Drought Webinar Series. The first webinar is Thursday, October 10 at 12 p.m. PT.
• State and regional drought information can be found on drought.gov: California, Nevada, California-Nevada Drought Early Warning System.

Drought and Climate Update and Outlook

Speaker: Julie Kalansky | California-Nevada Adaptation Program (CNAP, a NOAA CAP Team), Scripps Institute of Oceanography at the University of California San Diego 

• Summer was hot and dry for the region with high evaporative demand over the last 3 months in the southern two-thirds of California and most of Nevada. 
• Consequently, as of September 19, 10.67% of California and 32.32% of Nevada are in Moderate Drought (D1). 
• These conditions, combined with low soil moisture, have led to crop and rangeland impacts as seen in the Vegetation Drought Response Index (VegDRI). 
• Streamflow and reservoir levels are still near or above normal in much of the region. 
• The Climate Prediction Center's October outlook favors above-normal temperatures in the southern part of California-Nevada. There is currently a La Niña watch. 

California-Nevada Wildland Fire Potential Outlook

Speaker: Brent Wachter | U.S. Department of Agriculture, Northern California Operations

• Summer Conditions: 
  • The Winter–Spring growing season led to abundant and continuous herbaceous fuel loading. 
  • Extended hot and dry periods led to an unusually long period of flammable to critically flammable fuel. 
  • Wind events provided more significant growth periods compared to lightning events. 
  • California should end up near average as far as fire growth while Nevada is below average. 
• Going Forward:
  • Mixed signals with fall likely to be warmer and drier, although some timely cool-moisture intrusions should benefit northern areas. 
  • Seasonality with lessening sun angles and shorter daylight hours will help reduce fire danger. 
  • The season doesn’t fully “end” in California until there is lower-elevation green-up and higher-elevation snow. 
  • Fall Santa Ana season is expected to be active and combine with abundant dead grass and cured shrubs. 
• You can find more information on the outlooks at NIFC.gov.

Anthropogenic Intensification of Cool-Season Precipitation Is Not Yet Detectable Across the Western United States

Speaker: Park Williams | University of California, Los Angeles

• In the western U.S., cool-season daily precipitation totals did not intensify over the past ~75 years. 
• Atmospheric circulation trends have prevented the expected increases in atmospheric moisture transports from the Pacific Ocean. 
• Climate projections vary widely in terms of when intensified precipitation becomes statistically detectable from historical variability. 
• In California, most models suggest this will not occur until the 2070s or later. 
• If models are correct about intensification, record-breaking daily totals will begin accumulating well before intensified storms are consistent enough to be statistically detectable. 
• Read the journal publication in JGR Atmospheres.

Q&A and Conclusion

Speaker: Amanda Sheffield | CIRES/NOAA/NIDIS California-Nevada Regional Drought Information Coordinator

• Register now for the next webinar in this series on Monday, December 2, 2024 at 11 a.m. PT.