Trinity Center, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

450
FXUS66 KEKA 050929
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
129 AM PST Fri Dec 5 2025

.SYNOPSIS...A deepening marine layer will return along the coast
with patchy drizzle. King tides combined with tidal anomaly will
continue to bring the threat of coastal flooding in low-lying
areas around Humboldt Bay today. A series of frontal systems
moving north of the area will bring a chance of light rain or
sprinkles across the northern portion of the area through the
weekend, especially for Del Norte and Humboldt counties.



&&

.DISCUSSION...High pressure over the Northeastern Pacific has
slightly "flattened" as a series of shortwaves and associated
frontal systems move around the northern periphery of the ridge
towards the Pacific Northwest.

Downstream flow aloft will continue to bring increasing
cloudiness to the area as a weak cold front traverses the Pacific
Northwest. This should aid in a deep marine layer along the North
Coast. Patchy drizzle has already been observed as of 09z this
morning as the deepening marine layer and saturated profile
confirms the previous model data. Overnight temperatures are
forecast to run up to 5 degrees warmer compared with Thursday`s
morning. High dew points in the mid 30s to mid 40s will preclude
frost conditions across much of the interior valleys.

With fronts approaching the area from the north, chances increase
for light rain or sprinkles across Del Norte, Humboldt and
Trinity counties this afternoon and well into the evening. Dry
weather conditions are expected to prevail in Mendocino and Lake
counties. Some blustery winds will continue over the coastal
headlands and exposed ridges in Humboldt and Mendocino counties.
Lingering light showers will continue across the northern portion
of the forecast area on Saturday.

On Sunday, another shortwave and frontal system is expected to move
north of our area. The flow aloft will become more zonal, bringing
additional chances of light rain across the northern portion,
especially for Del Norte and northern Humboldt counties.
Elsewhere, partly to mostly cloud skies are expected.

The 500 mb ridge appears to slowly build back early next through mid
next week. WPC ensemble clusters do show about an even split (50%)
of clusters that are "drier" (at least for the North Coast) than the
grand ensemble mean. The ensemble mean is by no stretch very wet
with 0.10-0.25 inches of rain in 24 hours everyday from Monday
through Wednesday, mostly for Del Norte. It could be wet or it could
be dry or both. Stay tuned. -ZVS


&&

.AVIATION...(06Z TAFS)...Ceilings will continue to lower for coastal
terminals into early Friday morning as a weather system passes to
the north of the area. The marine stratus will deepen, with ceilings
in the IFR to high LIFR range. Some drizzle may occur at coastal
terminals early Friday. Interior valleys may also experience low
clouds/fog. It is still unclear if lower ceilings will make it to
KUKI, but there is a definite possibility early Friday. Through the
day Friday ceilings are expected to raise and stratus is anticipated
to push back toward the immediate coast. However, MVFR ceilings may
persist through the day for coastal terminals.


&&

.MARINE...Into Friday morning, northerly winds are expected to move
closer to the Mendocino coast, but remain 15 to 20 kt with the
strongest winds in the lee of Cape Mendocino. The swell remains
fairly low, currently around 2 to 4 feet at 12 seconds and this is
generally expected to continue through Friday.

Friday afternoon and overnight a front approaching the area will
bring a short period of light southerly winds to the northern inner
waters with the outer waters turning westerly. Farther south, winds
will remain northerly around 10 to 18 kt. Over the weekend winds
become southerly north of Cape Mendocino, but only around 5 to 10
kt. Farther south, the northerly winds persist and are around 10 to
15 kt.  This pattern is expected to generally continue through
Wednesday with winds remaining fairly light as a series of weather
systems moves by to the north of the area.

Saturday, a larger northwest swell builds into the waters. Currently
it looks to be around 6 to 9 feet at 10 to 12 seconds. This is
expected to diminish to around 5 to 7 feet on Sunday and generally
fluctuate around 5 to 7 feet at 12 seconds into early next week.
-MKK


&&

.COASTAL FLOODING...High astronomical tides are predicted to peak
on today. High tides are forecast to be at 8.80 feet at the North
Spit tide gauge at around 10:55 AM local time. High tides
combined with surge and tidal anomaly will result in water levels
between 9.1 to 9.3 feet MLLW (Mean Low Level Water). Minor coastal
flooding around Humboldt Bay, including King Salmon and Jackson
Ranch Road in the Arcata Bottoms, will be likely between 10AM and
noon. A Coastal Flooding Advisory will be in effect from 10AM to
noon on Friday. High tides are predicted to be at 8.63 feet at
11:44 PM on Saturday. This may cause minor flooding again on
Saturday, with water level remaining nearly half of a foot above
astronomical tides inside Humboldt Bay. -ZVS


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Coastal Flood Advisory from 10 AM this morning to noon PST
     today for CAZ103.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 11 PM PST this evening for
     PZZ475.

&&

$$

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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https://www.weather.gov/images/eka/zonemap.png