FOUS30 KWBC 221931
QPFERD
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
231 PM EST Sun Feb 22 2026
Day 1
Valid 16Z Sun Feb 22 2026 - 12Z Mon Feb 23 2026
The probability of rainfall exceeding flash flood guidance is less
than 5 percent.
A band of strong convection was currently located just west of
Eureka, CA and was exhibiting slow eastward movement and rain rates
approaching 0.5-0.75 inch/hr. This band may hold together long
enough to spread locally heavy rain into Humboldt County, CA -
although larger-scale/synoptic forcing should gradually and
progressively limit flood/flash flood potential through the day.
Heavy rainfall risk from Humboldt County, CA into Curry County, OR
should remain isolated enough to preclude Marginal/5% probabilities
for this outlook, though isolated instances of excessive runoff
cannot be completely ruled out.
Cook
Day 2
Valid 12Z Mon Feb 23 2026 - 12Z Tue Feb 24 2026
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHWESTERN WASHINGTON, ALL OF WESTERN OREGON, AND INTO PORTIONS
OF NORTHERN CALIFORNIA...
1930 UTC Update: Only minor changes made to the Day 2 Marginal Risk
area based on the latest QPF guidance.
Hurley
A deep positively tilted trough extends from around Vancouver=20
Island southwest down past the Hawaiian Islands at the start of the
period 12Z Monday. This trough extending that far south will draw=20
deep tropical warmth and moisture and rapidly draw it northeastward
into the Pacific Northwest on a 170 kt southwesterly jet. At the=20
surface, a low west of Vancouver Island will track southwestward=20
and merge with a weaker, smaller low. This will allow an impulse of
tropical moisture departing from the Hawaiian Islands to track=20
into the Oregon and Washington coasts by Monday night as a weak=20
surface low develops within the moisture plume.
Rain associated with the onshore flow will impact mainly the
Washington and Oregon coasts during the day Monday, gradually
sinking south in response to the approaching impulse of moisture
from the tropics. The low and associated heavy rain moves into the
coast near the OR/CA border Monday night. Since its track is
somewhat parallel to the coast, a rather small percentage of the
moisture will penetrate into the interior, so the coastal mountains
are likely to take the lion's share of the associated rain. The
warmth moving into the coast will allow snow levels across much of
Northern California to rise above 8,000 ft Monday night around the
OR/CA border, and above 10,000 ft further south towards the Bay
Area and Sacramento. This will initiate the snowmelt process across
all of the coastal Ranges and Sierra Nevada Mountains. The
inherited Marginal Risk remains unchanged for this area as recent
cold and snow has kept stream and creek levels at low levels. Thus,
the rain and snowmelt will begin to contribute to stream rises but
flooding should remain rather isolated as much of the rain gets
absorbed into the snowpack.
Wegman
Day 3
Valid 12Z Tue Feb 24 2026 - 12Z Wed Feb 25 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
NORTHERN SIERRA NEVADA MOUNTAINS AND ADJACENT FOOTHILLS...
1930 UTC Update: Made minor modifications to the Slight Risk area,
based on the latest model QPFs, as well as the latest 48hr snowmelt
projection from the National Snow Analyses page
(nohrsc.noaa.gov/nsa). Meteorological details below continue to
suffice for this event. Per additional collaboration with the
National Water Center (NWC) earlier today, the combination of heavy
rainfall and snowmelt may result in localized flash flooding along
small streams as well as in poor drainage areas.=20
Hurley
Previous discussion below...
A deep positively tilted trough that extends from Vancouver Island
southwest through the Hawaiian Islands will remain the primary
steering mechanism for an atmospheric river from the tropics and
into Oregon. This moisture will be aided by a 150 kt southwesterly
jet. This jet and the downstream ridging over the Southwest will
flatten out as the trough cuts off into an upper low well north and
east of Hawaii. This will cut off the feed of tropical moisture
into the West Coast by Tuesday night. Thus, the period of heaviest
rains will be primarily during the day Tuesday. A surface low
Tuesday morning will be near where the coast meets with the CA/OR
border. Since the rain associated with the low has origins in the
tropics, associated elevated instability, anomalous warmth and
moisture will all move into northern California. Snow levels will
rise to over 8,000 ft over much of northern California, and over
9,000 ft across much of the northern Sierra Nevada. This will
result in occasionally heavy rain associated with elevated
convection that quickly tracks northeastward into northern
California. Rainfall rates could exceed 3/4 inches per hour at
times.
Meanwhile recent abundant heavy snow from abnormally low snow
levels will be replaced with this tropical moisture and warmth. The
now very high snow levels will initiate the snow melting process.
When the heavy rain moves in over that snow pack, expect initial
absorption of the rain by the snow pack Tuesday morning, but as
more rain moves in Tuesday afternoon, it's likely that areas of
less deep snowpack, such as the foothills of the Sierra Nevada and
the Shasta, Siskiyou, and Salmon Ranges will all see rapid runoff
occur, sending local streams, creeks, and rivers rising very
quickly. This will be the combined result of both heavy rain and
fast snow melt. Given the expected rapid rises from both small
creeks to large rivers, flash flooding is likely to be a bit more
widespread. Thus, a Slight Risk upgrade has been hoisted for the
Sierra Nevada foothills, where the heaviest rains are expected due
to the greatest magnitude of upslope. However, heavy rains into the
other Northern California ranges may necessitate an expansion of
the Slight Risk with future updates.
Wegman
Day 1 threat area:
https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!9RDR4-jPF1atyvd23JbSTSLNn7xYE2k5dumjY8WGQndt= xn2mOZGNdAZDKSIV7sQ_4N_GqvGtrgBISkcwgqB9-Xv7-fU$=20
Day 2 threat area:
https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!9RDR4-jPF1atyvd23JbSTSLNn7xYE2k5dumjY8WGQndt= xn2mOZGNdAZDKSIV7sQ_4N_GqvGtrgBISkcwgqB9Zdx3BIY$=20
Day 3 threat area:
https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!9RDR4-jPF1atyvd23JbSTSLNn7xYE2k5dumjY8WGQndt= xn2mOZGNdAZDKSIV7sQ_4N_GqvGtrgBISkcwgqB9W6FCN_M$=20
=3D =3D =3D
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