970
FXUS66 KEKA 022308
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
308 PM PST Tue Dec 2 2025

.SYNOPSIS...High pressure build over the area is bringing offshore
flow and generally clear skies to the area through Thursday along
with night and morning valley fog. Light rain is possible mainly
in Humboldt and Del Norte counties over the weekend.


&&

KEY MESSAGES:

* King Tides from December 3rd-7th may lead to minor coastal
  flooding in low-lying areas mainly around Humboldt Bay.

* Frost is possible Wednesday and Thursday morning in the colder
  valleys and along the coast.

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

&&

.DISCUSSION...High pressure over the area is bringing fairly
robust offshore flow to the area tonight. East winds will bring
breezy on the ridges both Wednesday and Thursday mornings. These
are expected to be the strongest Wednesday morning. Gusts to 30 to
35 mph are possible on some of the higher peaks, especially in
eastern Lake county. These may mix down to some of the northeast
to southwest oriented valleys. This is expected to limit fog
development and may allow frost to form in the some of the
valleys that haven`t frozen yet. So have issued a frost advisory
for a number of these areas. It is still possible low clouds will
be more widespread than expected, but for now it looks like frost
is likely. Wednesday another dry day is expected. Any valleys
that do fog up will likely be slow to clear out and warm up
during the day. Wednesday night into Thursday morning is expected
to see lighter winds aloft, but they air is expected to be drier.
This would make it likely to be slightly colder Thursday morning.

Thursday night into Friday morning a shortwave coming over the
ridge is expected to start bringing more cloudiness to the area.
This will likely keep temperatures warmer. It is possible this
could bring some drizzle to the northern coastal areas, but
confidence is low on this. Friday afternoon looks like the first
chance for some light rain and this may continue through the
weekend. The big question is how far south this rain will come.
The current forecast keeps most of it in Del Norte county with
less than a quarter of an inch in northern Humboldt county. Del
Norte count may see over a half inch. However this is a small
system and a slight shift farther north or south could really
change the rainfall totals. This is highlight in the 75th and 25th
percentiles from the NBM. The 25th percentile for Crescent City
shows 0.2 inches while the 75th percentile shows 1.1 inches. In
Eureka and much of Humboldt and Trinity counties those amounts
range from 0.00 to 0.5 inches. Farther south and east in southern
Trinity, Mendocino and Lake counties even the high ends amounts
are less than a quarter inch. Even if the heavier amounts make it
farther south, there aren`t expected to be many impacts. MKK

&&

.AVIATION...High pressure and offshore flow are bringing VFR
conditions to the area this afternoon. These are expected to
continue tonight along the coast and some of the inland valleys.
There will be some stronger northeast winds aloft as well. This
will help limit some of the valley fog tonight, especially in the
northeast to southwest oriented valleys. This may also bring some
low level wind shear or turbulence. 20 to 30 kt of northeast wind
are expected down to a few thousand feet above the surface. Any
fog that does form tonight should clear out by mid to late morning
Wednesday. MKK

&&

.MARINE...Northerly winds have strengthened and moved closer to
the coast this afternoon. Gale force gusts up to 35 kts are
likely occurring in the outer waters, with gusts up 20-25 kts
possible nearshore. Steep seas have started to increase and are
combining with the northerly swell around 10 feet at 15 seconds.
Combined seas could reach 10-14 ft by early Wednesday morning.
Winds ease slightly by Wednesday but gusts up to 30 kts are still
possible in the outer waters. Winds and seas ease further Thursday
and Friday, with the main exception being the expansion fan south
of Cape Mendocino. Conditions continue to improve going into the
weekend as high pressure weakens. MKK/JB

.COASTAL FLOODING...High astronomical tides are predicted from
through Sunday for Northwest California. Water levels remain
nearly a have a foot above astronomical tides inside Humboldt Bay
and this may cause minor flooding starting Wednesday so have
issued a coastal flood advisory for Humboldt Bay. The tides
continue to get higher over the next several days and additional
flooding is expected around Humbodlt Bay. Outside of Humboldt Bay
the tide gauges are showing a slight negative anomaly and the
swell continues to diminish. At this point we aren`t expecting
coastal flooding outside of Humboldt Bay, but this will need to be
watched as it gets closer. MKK

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Beach Hazards Statement until 3 PM PST this afternoon for
     CAZ101-103-104-109.

     Frost Advisory from midnight tonight to 9 AM PST Wednesday
     for CAZ103>106-109-112-113.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 10 AM PST Wednesday for PZZ450.

     Small Craft Advisory from 4 PM this afternoon to 10 AM PST
     Wednesday for PZZ455.

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

     Gale Warning from 4 PM this afternoon 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