581
FXUS66 KEKA 042125
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
225 PM PDT Fri Sep 4 2026

.KEY MESSAGES...

* A general troughing pattern will bring additional light rain over
  the region today and periods of unsettled weather over the weekend.

* Overnight temperatures for the interior will remain chilly, yet
  fog formation will likely inhibit any frost forming within
  inland valleys.

&&

.SYNOPSIS...A low pressure system over western Oregon will
continue to funnel light rain over the region today with another
round of unsettled weather expected Sunday. Chilly temperatures
are forecasted for the interior each morning this weekend as well.


&&

.DISCUSSION...An upper level trough is lingering over western
Oregon this Friday. This feature is responsible for a deepened,
clearer marine layer, light rain showers for the North Coast, and
cooler temperatures inland. Short wave disturbances are
anticipated to flow downstream over NW CA through the weekend
increasing the chances for light rain showers, especially for
Sunday. The interior will likely see morning cloud coverage
dissipating to cooler temperatures through Monday. Morning
temperatures are beginning to reach Frost Advisory criteria with
some inland valleys getting as cold as the mid 30s by early dawn.
That said, a frost advisory has not been issued due to the
increased, insulating cloud coverage for major valleys.

Sunday, a shortwave disturbance passing over the forecast area
is increasing the rainfall chances for the Del Norte and the northern
portions of Trinity and Humboldt counties. A slight lightning
chance exists for these areas well, yet NW storm motion will
likely cause any storms that do form to flow into Siskiyou County
quickly. Little chances for wetting rain (>0.10") exist for areas
away from the high terrain inland for Sunday as well.

A slight warmup is possible next week as well, yet if it occurs,
it should be mild and short lived as ta troughing pattern returns
at the end of the coming work week. There are also questions
about whether tropical moisture may stream northeast toward the
region from decaying tropical systems well off the coast. Model
guidance has a large variance in possibilities ranging from
completely dry after Sunday to several chances of showers and
possibly thunderstorms mid to late week. That said, both the
deterministic GFS & ECMWF are showing rain for the North Coast
Saturday (+210hr) in both the 9/4/00Z and the 9/4/12Z runs.


&&

.AVIATION...18Z UPDATE...MVFR ceilings remain for much of NW CA
this morning. Satellite imagery shows clear conditions off the
coast which will likely lead to clearing to VFR along the coast
through the afternoon. Southerly winds continue through the
morning before veering to SW and eventually W through the
afternoon as well. This onshore wind could bring haze due to large
breaking waves, yet minimal impacts are expected. Models suggest
the deep marine layer will persist through the evening leading to
MVFR ceilings from 04Z onward before early morning clearing along
the coast. Inland terminals in Mendocino and Lake Co. can expect
VFR with north winds. Northern inland terminals can expect MVFR
with clouds blocking some of the taller mountains in Trinity,
Humboldt, and Del Norte Co.


&&

.MARINE...A continuously evolving low pressure center over
western Oregon is beginning to weaken. As a result, southerly
winds are likely to weaken through the evening before turning
northerly by early Saturday. Waves during this time are expected
to remain below small craft advisory conditions. Northerlies are
likely to be between 8-12kts with sporadic gusts up to 15kts with
the strongest winds in the far northern waters downwind of Cape
Blanco and in the southern waters downwind of Cape Mendocino. The
northerlies do not look to fully strengthen again until early next
week. Hurricane Marie will deliver a long period southerly swell
Saturday. Though small, at around 4 ft at 16 seconds, this swell
is a larger than typical swell from this direction at this time of
year.


&&

.BEACH HAZARDS...Hurricane Marie is expected to send a long
period, southerly swell of ~3-4 feet at 16 seconds this weekend.
This swell increases the risk of sneaker waves for south facing
beaches from Saturday into Sunday. The possibility of increased
risk for sneaker waves exists, especially if the swell comes in
slightly larger. If so, updates will be posted here.

Sneaker waves are a unique hazard. With up to 30 minutes between
waves, large waves can unexpectedly sweep across the beach
without warning. These waves are capable of sweeping people into
the sea from rocks, jetties, and steep beaches. These sneaker
waves can also move large objects such as logs, crushing anyone
caught underneath. Even ankle to knee deep water can knock you
down and drag you out when a sneaker wave hits due to sand giving
out quickly under ones feet. Pay attention and stay above the
high water line and any wet sand to stay safe. If the ground is
wet, waves have surged there recently. Stay safe and never turn
your back on the ocean!


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Beach Hazards Statement from late tonight through Monday
     evening for CAZ104-109.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 PM PDT this afternoon for
     PZZ450-470.

&&

$$

NOTE: The full forecast discussion is now regularly issued between
10 am/pm and 1 pm/am. Additional updates will be issued as needed.

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For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png