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SPRING FLOOD POTENTIAL OUTLOOK NATIONAL WEATHER SERVICE

CALIFORNIA-NEVADA RIVER FORECAST CENTER SACRAMENTO CA

1240 PM PST FRI FEB 28 2025









LOW FLOOD THREAT DUE TO SPRING SNOWMELT ACROSS CALIFORNIA



The potential for flooding due to spring snowmelt in the California

Nevada River Forecast Centers domain is fairly low given that the

state-average snowpack is below normal.  CPC is showing above normal

precipitation for the first half of March which could push snowpack

conditions to slightly above normal in the north, but remain below

normal in the Sourthern Sierra.  Even considering the upcoming wet

period, flooding due to snowmelt remains low.



In California, the areas with the highest risk of snowmelt flooding

are in mountainous areas of the Cascades and the Sierra Nevada.



Note that flooding in California could also result from heavy

rainfall alone, or combined with snowmelt anytime during the spring.



CURRENT BASIN CONDITIONS



SNOWPACK



The Northern Sierra & Trinity regions are currently 104% of average

for this time of year.  The Central and Southern Sierra are 70-80%

of normal.  Statewide, snowpack is 85% of normal.  These percentages

are expected to increase due to the upcoming wet pattern expected

during the first half of March.



PRECIPITATION



Precipitation totals for the current water year are generally above

normal in northern California (110 to 130%), but below normal for

the Southern Sierra (65-75%).



SEASONAL (APRIL-JULY) RUNOFF FORECASTS



The seasonal runoff projections have a similar pattern to the

precipitation.  The seasonal runoff forecasts for the  Upper Klamath

area we are well above normal.  The Upper Sacramento is expecting

slightly above normal runoff.  The Feather, Yuba, and

American watersheds are expecting near normal seasonal runoff.

Much of the Southern Sierra is expecting below normal seasonal

runoff.



FLOOD EXCEEDANCE PROBABILITIES



Flood potential due to pure snowmelt is fairly low this spring.

The Merced River has the highest chance of exceeding flood stage

during the snowmelt season with a 10-25% chance.  It is important to

note that potential for large springtime rainfall events resulting

in river flooding is still present and should be monitored

throughout the spring.  Consult the NWPS long range flood risk map

for the latest point exceedance probabilities:

https://water.noaa.gov/long_range



SUMMARY



Risk of California flooding due to pure snowmelt is fairly low given

the current snowpack conditions.  Refer to the long range outlook

product for flood exceedance probabilities at particular locations

https://water.noaa.gov/long_range) for the March through

May period.  Flooding due to rainfall is still a risk for much of

the spring season.  Consult the CNRFC homepage for near-term flood

threats:  https://www.cnrfc.noaa.gov/.