422
FXUS66 KEKA 290722
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1222 AM PDT Tue Sep 29 2026

.KEY MESSAGES...

* High pressure builds through the rest of the week, bringing an
  extended dry period with interior valley high temperatures warming
  into the 80s and 90s.

* An arriving long-period west-northwest swell brings an elevated
  risk for sneaker waves along the shoreline.

&&

.SYNOPSIS...Upper-level ridging builds over the West Coast this
week, supporting a progressive inland warming trend and dry
conditions through this coming weekend.


&&

.DISCUSSION...Broad mid-level ridging over the eastern Pacific will
expand inland Tuesday through Friday, establishing high confidence
in dry conditions across the region.

At the surface, the onshore pressure gradient between the offshore
eastern Pacific high and the interior thermal low will drive fresh
northerly winds along shore, strongest south of Cape Mendocino.
Additionally, conditions will be gusty for many locations across
Northwest California. Gusts greater than 20 mph could be possible
Tuesday afternoon/evening with an 80% chance or higher for
coastal areas from Del Norte to Mendocino, and more widespread
chances for all of southern Humboldt and most of Mendocino and
Lake counties, and for the ridges of Del Norte and Trinity
counties. There is an 80 percent chance or higher for gusts over
25 mph for all coastal areas along with the King Range, with more
widespread chances for Tuesday evening.

Strong atmospheric sinking beneath the upper ridge will steadily
warm the air mass aloft. Thermal profiles across interior valleys
will support afternoon maximum temperatures climbing into the 80s
and 90s mid-week. Ensemble guidance highlights an 80% probability of
interior valley highs exceeding 90F Wednesday and Thursday.


&&

.AVIATION...Gusty winds kept the terminals clear for most of the
evening Monday but overnight there could be a few areas with light
or patchy stratus coverage. As the mid level ridge set in there
will be more drying and subsidence, and the soundings do show
inversions at low levels. A mist or haze at various heights may be
visible during Tuesday morning. Winds do switch bearing from
southerly to easterly and finally northerly by Tuesday afternoon,
with light winds the variation will not be as dramatic for flight
safety. Due to an ongoing ASOS communications outage at KUKI,
automated observations are unavailable and amendments are not
scheduled.


&&

.MARINE...Fresh northerlies continue due to the pressure gradient
between offshore high pressure and the interior thermal trough.

* Northern Inner Waters: Northerlies of 10 to 20 kt will generate
  steep short-period seas. A west-northwest swell at 15 to 17
  seconds arrives today. A Small Craft Advisory remains in effect
  through Tuesday morning.

* Northern Outer Waters: Northerlies of 20 to 25 kt with gusts to 35
  kt (mainly in the lee of Cape Blanco) will build combined seas to
  10 to 11 ft. A Small Craft Advisory remains active through Tuesday
  morning.

* Southern Inner Waters: Fresh to strong northwest winds of 20 to 25
  kt with gusts to 35 kt (mainly in the lee of Cape Mendocino) will
  maintain steep seas. A Small Craft Advisory remains in effect
  through Tuesday morning.

* Southern Outer Waters: Gale force conditions develop in the lee
  of Cape Mendocino, where northerly winds of 25 to 30 kt with
  gusts up to 40 kt will yield steep, hazardous combined seas of
  11 to 12 ft. A Gale Warning remains in effect this afternoon
  through Wednesday morning.

&&

.BEACH HAZARDS...A long period west northwest swell at 3 to 6 ft with
a period up to 17 seconds is likely to diminish into Tuesday, also
lowering the threat of sneaker waves. The smaller period south
swell will continue to persist through Tuesday despite not being
as impactful. It is still in all beachgoers and water
recreationalists to use caution, especially on south facing
beaches. 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.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 AM PDT Wednesday for PZZ450-
     470.

     Small Craft Advisory until noon PDT Tuesday for PZZ455.

     Gale Warning from noon to 9 PM PDT Tuesday for PZZ455.

     Gale Warning until 3 PM PDT Wednesday 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