FOUS30 KWBC 020705
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
205 AM EST Thu Jan 2 2025

Day 1
Valid 12Z Thu Jan 02 2025 - 12Z Fri Jan 03 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHWESTERN OREGON AND NORTHWESTERN CALIFORNIA...

A relatively weak, long duration atmospheric river will continue=20
to impact portions of the Pacific Northwest coast today, shifting
focus from northwest California into far southwest Oregon. While
there is a distinct lack of instability to fuel rainfall rates
beyond 0.25"/hr, tropospheric moisture is still rather elevated
with precipitable water values of 1.0-1.2" (2.0-2.5+ standard
deviations, near the 95th percentile). Two distinct rounds of
precipitation (one from late this morning through mid afternoon,=20
and another round from late evening through the overnight) are
expected to bring additional rainfall of 3-5" (primarily for Del=20
Norte county, CA and Curry county, OR). While rapid onset flooding
is generally not expected (given the muted rainfall rates), these=20
areas (and surroundings) have already received 1-2" over the past
24 hours with USGS streamflow data indicating widespread above
normal to much above normal streamflows (with some even at record
territory for the date), suggesting additional rainfall may lead to
localized flooding impacts.=20

Churchill


Day 2
Valid 12Z Fri Jan 03 2025 - 12Z Sat Jan 04 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR FAR
SOUTHWESTERN OREGON AND PORTIONS OF NORTHERN CALIFORNIA...

A strong shortwave and associated surface low will plow into the
coast of California and Oregon on Friday. Locally heavy rain with
rates around 1/2 inch per hour will be ongoing Friday morning along
the coast. The shortwave and low will move into the coast Friday
evening and through the overnight. This will shift the heaviest
rains both southward and inland, bringing northern portions of the
Sacramento Valley, which has been largely missed with the previous
days' rains, into the potential for heavy rain and higher=20
elevation snow. The Marginal Risk inherited was left unchanged with
this issuance. The heaviest rains are likely to be Friday morning=20
as the aforementioned shortwave and surface low approach. Once they
move into the coast Friday evening and overnight, rainfall rates=20
should diminish quite a bit as the associated moisture moves=20
inland. Any flooding from the Day 2/Thursday period will likely=20
continue into Friday morning along the Oregon and California=20
coasts...with any minor flooding for the Sacramento Valley more=20
likely Friday afternoon.

Wegman


Day 3
Valid 12Z Sat Jan 04 2025 - 12Z Sun Jan 05 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Wegman


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/94epoints.txt__;!!DZ3fjg!55uWU4SqTkpkCTOn2LOuIf4nQ5yO2q682TwWm4S9O9PI=
z6JAbRjwqLGfnQC1IGn10IUCigIU-eIjOaHvr44l66L2Tp4$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/98epoints.txt__;!!DZ3fjg!55uWU4SqTkpkCTOn2LOuIf4nQ5yO2q682TwWm4S9O9PI=
z6JAbRjwqLGfnQC1IGn10IUCigIU-eIjOaHvr44lu8cSKx4$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/99epoints.txt__;!!DZ3fjg!55uWU4SqTkpkCTOn2LOuIf4nQ5yO2q682TwWm4S9O9PI=
z6JAbRjwqLGfnQC1IGn10IUCigIU-eIjOaHvr44loFLSZ9I$=20

=3D =3D =3D
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