412
FXUS66 KEKA 160727
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1227 AM PDT Thu Oct 16 2025

.SYNOPSIS...Cooler and cloudier conditions start to ease today, with
sunny, dry, and slightly warmer weather forecast through Saturday. A
quick moving chance of rain is possible again Sunday.


&&

.DISCUSSION...A few days of high pressure and calmer weather is
expected for NW California through Saturday. Tonight, inland valleys
seem to be holding moisture well with dew points between 40-45F.
This has given way to fog formation in inland valleys. The fog will
create an insulating layer, keeping the frost potential low tonight.
Friday morning however looks drier with max relative humidities
around 70% and dew points ranging between 25-35F in Trinity County
valleys. This drier air could create room for the cooling needed to
form frost, especially if winds remain calm overnight, which is
suggested by high resolution models. The forecast uncertainty lies
in if the radiational cooling inland reaches the temperatures needed
for frost. Nonetheless, the greatest chance for frost is in Northern
Trinity such as the valleys holding Weaverville, Hyampom, and
Hayfork.

The next weather system impacting NW CA will be a cold front passing
overhead early Sunday morning. At the current moment, Cluster
analysis and deterministic models show an upper level trough dipping
into the area. What the models don`t show at this point is many
details beyond a rough estimate of arrival timing. The rain is
currently expected to be confined to Del Norte, Humboldt, and
Trinity Co. NBM Cluster analysis shows the vast majority of outcomes
having under 0.50" of rain to Del Norte Co and 0.25" for Humboldt.
That said, the heavier model runs show accumulations of 1-1.5" for
the North Coast. The mountainous regions of Del Norte and NE
Humboldt can expected slightly higher accumulations up to 2-2.5" for
this storm. Snow accumulations for this cold front look not very
significant at this point with snow levels of 4500-5000` inland. The
current trend shows snow levels dipping to about 5500`. Uncertainty
with this storm is still significant however and the forecast is
subject to change. -ds


&&

.AVIATION...06/06Z TAFs...Mainly VFR to MVFR conditions at the
coastal terminals is expected through Thursday morning, followed by
persistent VFR conditions. Surface winds very light and variable,
becoming NNW at 10-15 kt with highest gust after 19Z...especially at
KCEC. The inland areas will likely see low clouds in the valleys
with some fog at cloud level above the valleys. Prevailing MVFR
ceilings at KUKI, improving to VFR after 16Z along with light and
variable winds. Offshore flow component is expected to develop
Thursday evening and increase Thursday night over the exposed
ridges, especially in Del Norte County where gusts from 25 to 35 mph
are likely over the higher terrain. This will yield clear skies
along much the coast late Thursday night and Friday. /ZVS


&&

.MARINE...Light northerly continue well offshore, while light
southerly winds continue closer to the coast this evening. Northerly
winds are expected to push back closer to the coast tonight into
Thursday. Winds are expected to gradually strength across the waters
early monring, then accelerate to strong to near gale force gust
conditions during Thursday afternoon and persist through Friday,
with the strongest winds south of Cape Mendocino where isolated gale
force gust is likely Friday afternoon.

Wind waves are expected to build to 6-8 feet Thursday evening. This
is expected to peak on Friday around 8-11 feet at 7-9 seconds. A
long period northwest swell arrive at 2-5 feet at 18-20 seconds
Friday evening , and then peak to 8-10 feet at 16 seconds Saturday
afternoon.

Saturday night into Sunday morning there may be some
brief southerly winds as a cold front swings through. The strength
and timing remain uncertain, but most models keep the winds below 20
kt. Northerly winds are expected to quickly return Sunday afternoon
or overnight. These are expected to increase to near gales or gales
at some point on Monday. /ZVS&MKK

&&

.BEACH HAZARDS...A long period westerly swell will arrive Friday
evening at 2 to 5 feet at 18 to 20 seconds, and peak to 8 to 10 feet
at 16 seconds Saturday afternoon. This high energy swell has the
potential to bring moderate risk of sneaker waves, especially early
Saturday evening. Shorter period NW swell of 6-8 ft at 7-9 seconds
may initially mitigate the risk during the morning and afternoon
hours. Depending on the short period wave components, a beach hazard
statement may need to issued. /ZVS


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from 4 PM this afternoon to 11 AM PDT
     Saturday for PZZ450.

     Small Craft Advisory from 4 PM this afternoon to 4 AM PDT
     Saturday for PZZ455.

     Small Craft Advisory from 11 AM this morning to 3 PM PDT
     Saturday for PZZ470-475.

&&

$$

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