910
FXUS66 KEKA 012218
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
218 PM PST Mon Dec 1 2025

.SYNOPSIS...High risk for sneaker waves Monday through Tuesday.
King Tides return on Tuesday and then peak Thursday and Friday.
Chances for frost and freezing temperatures increase for areas
closer to the coast again starting Tuesday night. Dry weather
expected to prevail for this week, followed by a chance for rain
late Friday and over the weekend.


&&

KEY MESSAGES:

* High risk of sneaker waves is expected along the Northwest
  California beaches through Tuesday morning.

* King Tides from December 2nd-7th, and may lead to minor coastal
  flooding in low-lying areas around Humboldt Bay, Crescent City and
  Arena Cove.

* Dry and seasonably cool weather expected through Friday, followed
  by a chance of rain over the weekend.


&&

.DISCUSSION...High pressure is forecast to remain parked over the
northeastern Pacific through Friday. Dry weather is highly probable
for NW California.

Offshore flow (E-NE winds) has been increasing across the interior
ridges overnight, especially in Lake County. Gusts from 25 to 35 mph
verified into Monday morning over the exposed ridges in the eastern
portion of Lake County. These winds are continuing to diminish
throughout the day as the surface pressure gradient relaxes.
Satellite imagery depicts only patchy low clouds near the Mendocino
coastal areas Mendocino this afternoon while sunshine remains
elsewhere.

Another "insider trough" will drive southward across the Great Basin
toward southern California Tuesday through Wednesday. This will
bring increasing high clouds across the area on Tuesday.
Ridging strengthen and upper-level heights rises across the Pacific
Northwest in the wake of the "insider trough". Stronger and blustery
coastal northerly winds are expected in the wake of this trough by
Tuesday afternoon. Gusts around 20-30 mph are forecast. East-
northeast winds will also develop Tuesday night into Wednesday for
the higher terrain and over Lake County, where gusts from 30-40 mph
will be possible over the ridges. Ridge level gusts to 40-45 mph are
on the limbs of the distribution (95th percentile and ensemble max)
over the high mountain peaks.

Chance for frost around Humboldt Bay area Tuesday morning decreases
to around 30% as another shortwave trough generates more cloud cover
tonight. Offshore flow resumes Tuesday night into Wednesday morning
and the chance for frost increases again to around 40-80% for the
Humboldt Bay area. Chance for 32F in the north of Humboldt Bay
increase to about 30-50% Wednesday morning. Meaningful chances for
early morning frost for the North Coast is expected to continue
Thursday morning.

The air mass is not forecast to be exceptionally cold next week.
With dew points in the 20s, calm winds in the valleys and clear
skies overnight, frost and freezing temperatures will once again be
a forecast challenge for inland areas that have not had a freeze
yet. Cold weather advisories for wind chill may also be a factor
with winds around around 5-10 mph and minimum temperatures in the
lower to mid 30s. Fog and low clouds will form each and every night
(100% chance), though the coverage will decrease as the air mass
slowly dries out each day this week.

Massive 500mb ridge appears to flatten out Friday and into next
weekend. All global ensemble prediction systems continue to indicate
increasing chances for 0.10 to 0.25 inches of rain in 24 hours
through the weekend. 24 hour chance for > 1 inch is no more than
20%. It is interesting to note that the majority of WPC ensemble
clusters are drier than the grand ensemble. The ensemble mean is by
no stretch very wet either. It could be wet or it could be dry or
both over multiple days. Stay tuned.


&&

.AVIATION...VFR conditions are expected through the afternoon into
the evening. There is a hint of valley fog forming inland possibly
bringing IFR/LIFR conditions to the Russian River Valley (KUKI).
However, the North coast looks to have enough of an offshore flow to
keep any developing marine stratus trapped in an eddy south of Cape
Mendocino. Light variable winds and the passage of high clouds are
expected for coastal terminals. /DS


&&

.MARINE...Moderate northerly winds have pull away from the coast
this afternoon. Steep seas will largely be confined to the outer
waters for much of the day. Wind waves are combining with a long
period westerly swell which will gradually build to up to 8 ft @ 18
seconds by Tuesday. Combined seas of 8-13 ft are expected. Stronger
northerly winds return tomorrow afternoon, with increasing forecast
confidence in gale force gusts in the outer waters south of Cape
Mendocino and Pt. St. George. Nearshore winds will be lighter, but
peak gusts of 15-25 kts are still possible as are propagating steep
wind waves making conditions hazardous for Small Crafts. North winds
ease slightly and pull offshore by Wednesday. Conditions gradually
improve through the end of the week. JB/DS


&&

.BEACH HAZARDS...A long period swell, up to 22 seconds, will
continue to build in on Monday. This energetic swell is bringing a
high risk for sneaker waves, with surf breakers up to 15ft. The
threat will last through Tuesday. High astronomical tides will
increase the danger, especially over rocks and jetties.

Sneaker waves are a unique hazard, with up to 30 minutes between
waves. Large, unexpected waves can sweep across the beach without
warning, sweeping people into the sea from rocks, jetties, and
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.
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! /JJW


&&

.COASTAL FLOODING...King Tides return on Tuesday. High astronomical
tides are predicted from Tuesday through Sunday for Northwest
California. The combination of a high astronomical tides, a positive
tidal anomaly, and a long- period swell will increase the risk of
minor coastal flooding around Humboldt Bay, including King Salmon
and low-lying roads near Arcata Bottoms. /JJW


&&

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

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from 4 PM Tuesday to 3 AM PST
     Wednesday for PZZ450-455.

     Small Craft Advisory until 4 PM PST Tuesday for PZZ470-475.

     Gale Warning from 4 PM Tuesday to 8 AM PST Wednesday 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