822
FXUS66 KEKA 230825
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1225 AM PST Sun Nov 23 2025

.SYNOPSIS...Another cold morning is in store as clear skies
persist inland. A marine layer will likely build along the coast
early today with coastal drizzle incoming by the evening. Cool and
dry weather will return Monday and Tuesday.



&&

.DISCUSSION...Offshore flow continuing overnight combined with drier
air may allow for patchy frost formation in interior valleys of
Trinity and NE Mendocino counties early this morning. That said, the
addition of moisture to the environment from the recent rain is
already enabling the formation of fog, which reduces the likelihood
of frost formation. Frost concerns through this morning remains low
(less than 10% via HREF/REFS probabilities). Closer to the coast,
the marine layer has steadily been forming through the evening
hours. This cloud layer will insulate the coastline, stopping the
chance for frost early this morning. Interior highs will
generally return to the low to mid 60s this afternoon through
Thursday.

Most ensemble members show a weak trough moving onshore well north
of the area later this afternoon/evening through Monday morning.
Most members show light rain and drizzle along the North Coast in
Del Norte and Humboldt counties with a 90% chance of at least trace
rain amounts in Crescent City and an increasing probability (~20-
30%) of any amounts over 0.3 inches. In the Humboldt Bay area, there
is about a 40% chance of no rain at all and only a 20% chance of
greater than a wetting rain (>0.10"). High pressure will then again
most likely briefly build with about 70% of ensemble members showing
another cold, cutoff low storm system entering the area late next
week.

Clearer skies and offshore flow will quickly reassert themselves
early next week with another 50% chance of light frost in the
interior by Monday morning. Most ensemble members continue to show a
cold, cutoff low pressure system impacting the area mid to late next
week, though potential timing is very uncertain. At least some rain
is very likely, but the range is large (most likely 0.5 to 2.0
inches) because many models focus the system north. Compared to
previous model runs, more now show the system staying north of the
area (about 50%). Should rain occur, it will focus on the North
Coast. NBM shows snow levels of 3000 to 4500 feet on the back end of
the system into next weekend, which could bring some of the lowest
elevation (albeit very light) snow of the season so far. There is
little ensemble support (less than 20% over 45 mph) of any impactful
winds with the system. /JHW/DS


&&

.AVIATION...(6Z TAFs)...Stratus has developed along the coast north
of Cape Mendocino and up the river valleys. This is expected to
continue to expand overnight and may even make it into the Russian
River valley and KUKI towards morning. Sunday these clouds are
expected to take their time clearing, but most areas should be VFR
by midday or early afternoon. This will be shortlived as a frontal
boundary moving by to the north of the area is expected to bring
MVFR or IFR conditions to the KACV and KCEC along with some light
rain or drizzle. This is expected to linger for much of Sunday
night. COnfidence is low on how far inland this will make it. Monday
is expected to see clearing again. MKK


&&

.MARINE...Northerly winds are gradually diminishing as a weak
frontal boundary moves toward the area this morning. There may be a
brief period of southerly winds in the northern waters later this
afternoon and evening. The current swell has built in to around 11
to 12 feet at 15 seconds. This swell is expected to gradually
diminish, dropping below 10 feet by early Monday. In addition there
are some smaller wind driven waves that are gradually diminishing as
well.

Early on Monday northerly winds are expected to build back into the
area. These are expected to peak around 20 kt Monday afternoon and
evening before they start diminishing again Monday night. Tuesday
and Wednesday are generally expected to see fairly light winds.
Wednesday afternoon these are expected to start becoming southerly
again as a frontal boundary approaches the area.  There are still
some discrepancies in the models on how strong these winds are
expected to get on Wednesday night and early Thursday, but generally
they are expected to peak around 20 kt in the northern outer waters
with lighter winds farther south. Friday stronger northerly winds
are expected to return and models are in fairly good agreement on
this. Over the weekend the models start to diverge with some
bringing in another weak weather system and others bringing stronger
northerlies.

The swell is expected to continue to diminish Tuesday and Wednesday
with swell heights only around 4 to 6 feet at 10 seconds. The wind
driven waves are expected to diminish Tuesday night setting up a
very calm day on the water for Wednesday. Total wave heights look to
be around 4 feet with a dominant period of 12 seconds. The next
swell is expected to build in Thursday morning. MKK


&&

.BEACH HAZARDS...The long-period WNW swells continue to move
through the waters today. Periods are around 15 seconds and some set
behavior is expected to continue. These will pose a moderate risk of
sneaker waves through the day Sunday. Breaking wave heights may
reach 17-19 ft. Be cautious visiting beaches and jetties and
remember to never turn your back to the ocean!


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Beach Hazards Statement through this evening for CAZ101-103-
     104-109.

     Frost Advisory until 9 AM PST this morning for CAZ106>108-
     110-111.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until noon PST today for PZZ450.

     Small Craft Advisory until 6 PM PST this evening for PZZ455-
     475.

     Small Craft Advisory until 11 PM PST this evening for
     PZZ470.

&&

$$

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