Hydrologic Outlook

CAC003-005-007-009-011-017-021-035-057-061-063-067-077-089-091-
095-099-101-103-109-113-115-030415-

Hydrologic Outlook
National Weather Service Sacramento CA
810 AM PST Wed Mar 2 2022

...LOW SPRING FLOOD THREAT ACROSS CALIFORNIA & NEVADA...

The potential for flooding due to spring snowmelt in the California
Nevada River Forecast Center`s domain is below normal due to below
normal snowpack.

Flooding in California remains a slight possibility due to the
seasonal threat of heavy rainfall alone, or combined with snowmelt
anytime during the spring.

SNOWPACK

Everywhere from the northern portions of in the Klamath Basin down
to the Tulare Basin in the Southern Sierra Nevada is experiencing
below average snowpack. While December was a very productive month,
January and February totals were record lows. These two dry months
have driven snowpack amounts down from above normal to roughly 60%
in the Northern Sierra, 80% in the Central Sierra, and 65% in the
Southern Sierra.

SEASONAL PRECIPITATION

Precipitation totals for the current water year are about 90% of
average to date for the Northern Sierra, 75% in the San Joaquin, and
75% in the Tulare. December was an above normal month where much of
the Sierra was around 160% of average, but that has been followed by
a record low for January and February. Last year at this time
precipitation totals were about 50% of average.

SEASONAL (APRIL-JULY) RUNOFF FORECASTS

The seasonal runoff forecasts are very similar to the snowpack
conditions. Below normal runoff volumes can be expected during the
April-July period throughout the Cascades and the Sierra Nevada.

FLOOD EXCEEDANCE PROBABILITIES

Flooding potential during the spring snowmelt season is below normal
this season due to the below normal snowpack and the extremely dry
conditions experienced in January and February. The potential for
large springtime rainfall events resulting in river flooding is
still present and should be monitored throughout the spring. Consult
the AHPS long range flood risk map for the latest point exceedance
probabilities: http://water.weather.gov/ahps/long_range.php.

SUMMARY

Risk of California flooding during the snowmelt season is
below normal this year for the Cascades and the Sierra Nevada.
Nevertheless the possibility for flooding remains due to a
combination of rain and snowmelt at any time during the spring.

Refer to the long range outlook product for flood exceedance
probabilities at particular locations for the March through May
period. For short term hydrologic forecasts and general water
resource information, please see the cnrfc homepage at:
http://www.cnrfc.noaa.gov.


CNRFC/BW
WFO STO/HEC

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