247
FXUS66 KEKA 210831
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1231 AM PST Fri Nov 21 2025

.SYNOPSIS...Cold temperatures overnight are to be expected inland
this morning and Saturday morning. Conditions will quickly warm and
dry into the weekend with light drizzle along the coast early next
week.


&&

.DISCUSSION...Offshore flow continuing overnight combined with drier
air may allow for patchy frost formation in interior valleys of
Trinity and NE Mendocino counties. That said, the addition of
moisture to the environment from rain is already showing to enable
the formation of fog, which reduces the likelihood of frost
formation. Closer to the coast, unstable conditions will make any
marine layer formation unlikely, leading to clear skies with the
exception of radiation fog forming in the coldest lower elevations
spots.

Cold air will quickly be pulled east of the area with high pressure
and offshore flow generating quick warming and drying today into the
weekend. By Saturday, interior highs will generally return to the
mid 60s. Dry conditions may allow for continued frost concerns
through Saturday morning, but the chance of proper freeze conditions
remains low (less than 10% via HREF/REFS probabilities). Offshore
flow Saturday will likely also help keep the coast clear but winds
turning more onshore by Sunday will likely promote some coastal
stratus formation.

Most ensemble members show a weak trough moving onshore well north
of the area early next week. That said, 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,
however an increasing probability (~15-20%) of any amounts over 0.3
inches. In the Humboldt Bay area, there is a 45% chance of no rain
at all and less than 10% chance of even wetting rain (>0.01"). High
pressure will then again most likely briefly build over the area
by for Thanksgiving Day. /JHW&DES



&&

.AVIATION...(6Z TAFs)...Widespread low clouds are being observed in
the interior valleys, but so far these have mostly avoided the major
terminals. Weak offshore flow could promote some brief impacts to
all the terminals at times before sunrise. Clouds will likely lift
and scatter after sunrise, with VFR conditions likely through the
day Friday. Winds will generally shift northerly and generally
remain light. Offshore flow is likely to keep skies clear into the
overnight hours Friday night. JB


&&

.MARINE...Northerly winds have started to build as high pressure
begins to build. Meanwhile, a large WNW swell has filled in bringing
steep waves of 15-17 ft at 15 seconds. Seas have already started to
begin to ease and will continue to ease through the day. Northerly
winds will peak this afternoon and evening with gusts up to 30 kts
in the outer waters and 15-20 kts nearshore. Steep short period
waves of 6-10 ft will accompany these winds. Winds ease into
Saturday as the pressure gradient weakens. However, another large
long-period NW swell of 10-12 ft is forecast to fill in Saturday,
returning combined seas of 12-15 ft. Seas gradually subside going
into Sunday and Monday, but northerlies are likely to return Sunday
into Monday. Milder conditions are forecast to return by mid next
week. JB


&&

.BEACH HAZARDS...A large W-NW swell has filled in, bringing a risk
for dangerous surf through Friday morning. Breakers from 18 to 22
feet are being observed and large surf is likely to continue into
Friday morning. The swell is too large for sneaker wave criteria and
too low to warrant a high surf advisory, but still caution should be
exercised on beaches and jetties. A longer period W-NW swell group
from 8-12 ft with dominant periods near 16 seconds is forecast to
build over the weekend. This swell may pose a greater risk for
sneaker waves and continued erosion of beach profiles.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Frost Advisory until 10 AM PST this morning for CAZ107-108-
     111.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Hazardous Seas Warning until 9 AM PST this morning for
     PZZ450-455-470-475.

&&

$$

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