CALIFORNIA-NEVADA DEWS
CA-NV Water Year Recap & September Drought & Climate Webinar Recording
Thank you to the speakers and to those of you who participated in the September 2020 California-Nevada DEWS Drought & Climate Outlook Webinar. We have posted a recording for those that were unable to participate in the live event.
And if you can't wait for the next webinar, mark your calendar and register now for the next webinar on Monday, November 23, 2020.
Current U.S. Drought Monitor Conditions

  • Over the course of the 2020 Water Year (Oct. 2019 - Sept. 2020), drought intensified over California-Nevada. On Oct. 13, 2020, over 80% of California and Nevada was in drought, according to the U.S. Drought Monitor, including over 30% in extreme to exceptional drought (D3-D4).
  • Conditions worsened over the summer from continued upper level high pressure parked over the west, record heat, and a very weak monsoon.
U.S. Drought Monitor for CA/NV for Oct 13th. Source: https://droughtmonitor.unl.edu/
U.S. Drought Monitor 1 year change map for the West for Oct 13th. Source: https://droughtmonitor.unl.edu/Maps/ChangeMaps.aspx
End of Water Year Update

  • CA-NV saw a wet start to the water year, but January and February were dry - record dry in several areas (central CA and northern CA-NV). Wetness only returned in spring to parts of the southern part of the region.
  • This year’s monsoon produced little precipitation and much above normal summer temperatures including August records. 
  • Conditions led to intensified drought conditions, high evaporative demand, and record breaking wildfire season. Over 4 million acres burned in California as of early October.
Water year 2020 precipitation rankings. Source: WestWide Drought Tracker
Departure from normal temperature (oF) for the 2020 water year. Source: WestWide Drought Tracker
EDDI Maps from NOAA ESRL: https://psl.noaa.gov/eddi/ 
Drought & Climate Outlook
ENSO

La Niña conditions continued into Sept with below-average sea surface temperatures extending from the Date Line to the eastern Pacific Ocean. NOAA’s ENSO alert system status is currently a La Niña advisory and is likely to continue through the Northern Hemisphere winter 2020-21 (~85% chance) and into spring 2021 (~60% chance during February-April). For more information, check out the NOAA ENSO blog. 
Seasonal Drought Outlook

Drought is expected to develop across Southern California. In contrast, conditions are expected to improve in the very northern part of the state. In the middle, and throughout Nevada, drought is expected to persist.
U.S. Seasonal Drought Outlook. Source: NOAA NWS Climate Prediction Center
Temperature

Warm temperatures are favored over California-Nevada through early winter with >40% chance of above-normal November-January temperatures.
November to January Temperature Outlook. A = chances of above-normal; EC= equal chances of above, below, normal; B = chances of below-normal. Source: NOAA NWS Climate Prediction Center
Precipitation

The southern part of California and Nevada are forecasted to be drier than normal (33% chance) for November-January, following the historical pattern of La Niña. However, some La Niña years in the recent past have been exceptions to the “typical” pattern.
November to January Precipitation Outlook. A = chances of above-normal; EC= equal chances of above, below, normal; B = chances of below-normal. Source: NOAA NWS Climate Prediction Center
Past ENSO status vs October-March Precipitation for coastal southern California. Past La Ninas are shown in blue. Additional regions can be found at https://wrcc.dri.edu/Climate/soi_precip.php
Wildland Fire

Ongoing large fire activity, La Niña, and current fuel conditions are the main drivers of significant fire potential through fall and into winter. Drought conditions are expected to continue for much of California, the Great Basin, and the southwest U.S. through October. Significant fire potential is forecast to remain above normal for California due to the number of active large fires, near record dry fuels, and anticipated offshore wind events. Above normal significant fire potential is also expected in eastern Nevada.
Acknowledgments 

  • Andrea Bair, NOAA National Weather Service Western Region
  • Shrad Shukla, UC Santa Barbara/CNAP
  • Dan McEvoy, Western Regional Climate Center/CNAP

\For webinar-related questions or suggestions, please contact: 
Amanda Sheffield, amanda.sheffield@noaa.gov