715
FXUS66 KEKA 010913
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
113 AM 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.
Frost and freezing temperatures possible during the morning hours
for the Humboldt Bay area Monday through Thursday. Dry weather
expected to prevail for this week, followed by a chance for rain
late Friday and next weekend.


&&
.KEY MESSAGES...

* High risk of sneaker waves is expected along the Northwest
  California beaches from this morning 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 are most likely into this morning over the exposed
ridges in the eastern portion of Lake County. Winds are expected
to diminish throughout the day as the surface pressure gradient
relaxes. Satellite imagery depicts patchy low clouds near the
coastal areas and patchy fog developing along the river valleys
overnight. As of 12 AM PST, high dewpoints in the upper 30s to low
40s have been precluding frost conditions along the coast north
of Humboldt Bay. However, frost remain probable, 70-90% chance,
for the north bay (Arcata, McKinleyville, Fieldbrook) as light
easterlies drive dewpoints down into early this morning. Chance
for a freeze is much lower, only 10-20%.

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 will be
possible. 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...(6Z TAFs)...VFR conditions are expected for the coastal
terminals as offshore flow limits stratus impacts. The interior
valleys, including UKI, could once again see LIFR stratus and fog
early Monday morning. Ceilings and visibilities are likely to
improve after sunrise, with generally VFR conditions likely by the
afternoon. JB


&&

.MARINE...Northerly winds have started to ease slightly and pull
away from the coast. Steep seas will largely be confined to the
outer waters for much of the day Monday. This will combine with a
long period westerly swell which will gradually build to up to 8 ft
by Tuesday. Combined seas of 8-12 ft are possible. Stronger
northerly winds return Tuesday, with gales possible south of Cape
Mendocino. Nearshore winds will be lighter, but peak gusts of 15-25
kts are still possible. North winds ease slightly and pull offshore
by Wednesday. Conditions gradually improve through the end of the
week. JB


&&

.BEACH HAZARDS...A long period swell (up to 22 seconds) will suddenly
build into the waters up to 8 feet midday Monday and continue into
Tuesday. With calm winds near shore, this swell will pose a high
sneaker wave risk with sudden high surf on beaches in otherwise calm
seeming conditions. Take extra care to keep distance from the water.
Building short period seas and shortening swell period will decrease
the risk by Tuesday afternoon. /JHW


&&

.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 and
steep, short-period northerly waves will increase the risk of
minor coastal flooding around Humboldt Bay on Wednesday, including
King Salmon and low-lying roads near Arcata Bottoms. Minor flooding
potential in low-lying areas around Humboldt Bay, and along much
of the coast is then expected through next Sunday. /ZVS


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Beach Hazards Statement from 8 AM PST Monday through
     Tuesday morning for CAZ101-103-104-109.

     Frost Advisory from 4 AM to 9 AM PST Monday for CAZ103.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 4 PM PST Tuesday for PZZ470-475.

     Gale Watch from Tuesday afternoon through Wednesday morning
     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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For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png