National Weather Service Text Product Display

Drought Information Statement
Issued by NWS San Francisco Bay Area, CA
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Drought Information Statement
National Weather Service San Francisco Bay Area
938 AM PDT Thu May 20 2021

...DROUGHT EMERGENCY PERSISTS WITH EXCEPTIONAL DROUGHT CONDITIONS
INTRODUCED OVER PORTIONS OF THE NORTH AND EAST BAYS

SYNOPSIS...

The drought emergency declared across 41 counties of California
on May 10, 2021, by Governor Newsom remains unchanged. The
emergency proclamation was issued in response to below normal
precipitation this year and a second consecutive year of dry
conditions. The declaration was expanded due to the warm spring
temperatures in the last 3 weeks that have led to a rapid
depletion of the Sierra Nevada snowpack, low streamflow, less
inflow into reservoirs, and hence a rapid deterioration of the
state`s water supply. The declaration paves the way to
expeditiously mitigate the effects of drought conditions to ensure
the protection of health, safety, and the environment. The
drought emergency declaration includes the following counties
within our Hydrologic Service Area (HSA; Sonoma, Napa, Alameda,
Contra Costa, and San Benito counties. https://www.gov.ca.gov/wp-
content/uploads/2021/05/5.10.2021-Drought-Proclamation.pdf

The latest drought classification from the U.S. Drought Monitor
issued today has introduced D4-Exceptional Drought into portions
of Napa, Sonoma, Marin, Contra Costa, and Alameda. D4-Exceptional
Drought classification indicates exceptional and widespread
crop/pasture losses and shortages of water in reservoirs, streams,
and wells creating water emergencies. The remaining portions of
Napa, Sonoma, Marin, Contra Costa, and Alameda, as well as all of
San Francisco, San Mateo, Santa Clara, Santa Cruz Counties, and
the northern portions of Monterey and San Benito Counties, remain
in D3-Extreme Drought. The central and southern portions of
Monterey and San Benito Counties remain unchanged in D2-Severe
Drought.

The drought classifications are due to below normal precipitation
for the 20/21 water year and compounding impacts from a second
drier than normal water year.


https://droughtmonitor.unl.edu/currentmap/statedroughtmonitor.aspx?ca

SUMMARY OF IMPACTS...

Having received less than 50% of average precipitation in the
current water year, numerous counties are beginning to see
significant impacts. Ranchers are seeing water supplies dry up and
dryland pasture growth stunted resulting in animal stress,
mortality, decreased stock weight and having to sell off
livestock. Farmers are preparing to haul water to their livestock.
Several counties are imposing or planning to impose limits,
reductions, and penalties for customers that exceed allocations.
Below-average precipitation has resulted in abnormally dry
vegetation as we head into the fire season. Our first Red Flag
Warning (RFW) of the season was issued this past weekend due to
extremely dry fuels. This is approximately 4 to 6 weeks earlier
than normal. The last time we issued a RFW in May was in 2013, the
start of the last drought.

CLIMATE SUMMARY...

Northern and central California saw around 50% or less of average
precipitation for the 20/21 water year, making this the 3rd
driest year on record. The northern and central Sierra Nevada
watersheds had built up a decent albeit below-average snowpack
with Phillips Station reporting 83% of average for the water year
on April 1st. However, the statewide snowpack average was only 59%
of average. The April 29th snow survey was canceled due to lack
of snow resulting from warm spring temperatures that melted and
evaporated most of the Sierra snowpack. Consequently, low
streamflow and less reservoir inflow, are underscoring the rapid
deterioration of the state`s water supply. At a state level,
California observed its 6th warmest April on record. Two
consecutive dry years have left reservoirs about half full. These
precipitation deficits, combined with high temperatures, have
reduced streamflow, dried out soils, and stressed vegetation.

PRECIPITATION/TEMPERATURE OUTLOOK...

CPC 3-month outlook for May-June-July shows below-normal
precipitation for the northern half of the state and above-normal
temperatures across the entire state.

La Nia has officially ended and we have transitioned from La
Nia to ENSO-neutral conditions. There is a 67% chance of ENSO-
neutral conditions continuing through the summer months (June-
July-August 2021). Looking to next fall, it is leaning towards
cool ENSO neutral. A second year La Nia event is also possible,
with back-to-back La Nia events happening about 50% of the time
when looking back at history. https://www.climate.gov/

NEXT ISSUANCE DATE...The next product update will be issued as
needed in response to significant changes in conditions.

&&

RELATED WEBSITES...
California Data Exchange Center:  http://cdec.water.ca.gov/
California Nevada River Forecast Center:  http://www.cnrfc.noaa.gov/
Drought Monitor:  http://drought.unl.edu/dm/monitor.html
California Drought Page: http://www.water.ca.gov/uhjywaterconditions/drought
Climate Prediction Center:  http://www.cpc.noaa.gov/index.php
National Weather Service San Francisco/Monterey Bay Area:  http://www.wrh.noaa.gov/mtr/
National Weather Service California drought information resources:
http://www.wrh.noaa.gov/wrh/droughtca.php
Association of California Water Agencies:  http://www.acwa.com

ACKNOWLEDGMENTS...
Climate Prediction Center
U.S. Drought Monitor
California Nevada River Forecast Center
National Weather Service San Francisco/Monterey Bay Area
California Department of Water Resources
California State Climatologist
U.S. Bureau of Reclamation
Cal Fire
Association of California Water Agencies
Local cities and counties

QUESTIONS AND COMMENTS...Please refer all questions to
w-mtr.webmaster@noaa.gov.

$$

CW

weather.gov/sanfrancisco
National Weather Service Weather Forecast Office
