483
FXUS66 KEKA 300708
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1208 AM PDT Tue Sep 30 2025

.SYNOPSIS...Another front will bring additional rain and strong
gusty southerly winds Tuesday afternoon through Tuesday night.
Lingering showers on Wednesday will diminish on Thursday. Dry
weather is expected Friday through the weekend.

&&

.DISCUSSION...An upper level low low is sitting well off the
Washington coast and has several shortwaves and associated frontal
systems moving around it. The first front moved through on Monday
bringing rain to much of the area. This has left the low levels
moist with fog developing in some areas. Today the next front is
expected to move through the area. This second one generally looks
to have less rain and more wind with it in Humboldt and Del Norte
counties. This is showing up well on water vapor this morning.
Most of the current models are showing the tenth to a quarter of
an inch of rain as this moves onshore. With the stronger winds
terrain effects are expected to more pronounced limiting the rain
in the Humboldt bay region and enhancing it on the south slopes,
especially in southern Humboldt and Del Norte counties. Local
amounts in the King Range and the mountains of Del Norte county
will likely exceed an inch. There are still some model solutions
that show a more widespread half inch or so of rain, but these may
not be capturing all of the terrain effects so they look like a
lower probability scenario.

The models are showing winds at 850MB of 30 to 40 kt over
Humboldt and Del Norte counties. The soundings are showing an
unstable layer near the surface that would allow this to mix down
to the surface at least over some of the higher terrain. This may
bring gusts of 40 to 50 mph over the higher terrain of Humboldt
county and along the coast near Crescent City. The wind advisory
looks to remain on track. Winds may not quite reach the 45 mph for
a wind advisory, but this is the first stronger southerly winds
of the fall and that may increase impacts.

Tuesday night and Wednesday the upper level low continues to spin
and push some showers across the area. The NBM is showing the
potential for some thunderstorms, but the soundings show some poor
lapse rates aloft that will likely prevent this. Thursday there
may be a few lingering showers, but these should be fairly
limited.

Friday through the weekend and into early next week dry weather is
expected to return. Strong high pressure builds over the eastern
Pacific. The uncertainty lies in exactly how far east this makes
it. It also looks like there will be some weather systems moving
down the east side of the ridge in an inside slider pattern. This
may create offshore flow bringing clear skies and dry conditions.
These clear and dry conditions will also bring the potential for
frost or freezing temperatures in the valleys. This will be highly
dependent on how much drying there is, but it is starting to look
like we will see frost at least in the colder areas. MKK

&&

.AVIATION...06z TAF...Post frontal conditions this evening have
generated highly variable and inconsistent conditions. Broken
ceilings have generally hovered around MVFR with both some breaks to
VFR and IFR conditions. Strong southerly wind will gradually begin
to build in by sunrise Tuesday. These winds will likely help mix low
level clouds and lift ceilings to VFR. At the same time, very
significant wind shear is expected for terminals on the North Coast,
especially around Humboldt bay with southeast surface winds
contrasting strongly with very strong southwest winds aloft. As more
unstable air move in afternoon, surface gusts near 40 kts are likely
along the coast, especially along exposed headlands. Ceilings will
gradually lower to MVFR as rain showers begin to build in Tuesday
afternoon, though most models show dry air near the surface making
it difficult to lower ceilings much below 2 kft. Low IFR
visibilities are possible (30% chance) late Tuesday night into early
Wednesday as winds finally begin to die down. /JHW

&&

.MARINE...An exiting storm system has left moderately steep waves up
to around 7 feet across all waters Monday night. A much windier
storm system will sweep across the waters Tuesday morning. Southerly
wind gusts will be strongest in the northern waters with some gusts
most likely in excess of 40 kts by mid Tuesday morning. Winds will
be greatest in the northern waters with consistent gale conditions
through the afternoon. The southern waters will see near gale force
conditions around Cape Mendocino but weaker gusts only around 24 kts
further south.

Short period seas will build as much as 8 feet but will not have
time to grow further as southerly wind quickly fall off by Tuesday
night, replaced by more gentle southerly breezes at least through
Thursday. Despite calming winds and short period seas, a mid period
swell will build up to 12 feet at 14 seconds by early Wednesday,
maintaining generally steep seas in all waters through at least
early Thursday morning. Wind will turn northerly late in the week
and begin to increase mostly south of Cape Mendocino. A resurgence of
near gale conditions are possible lee of the Cape by Saturday.
/JHW

&&

.BEACH HAZARDS...A steep, mid period northwest swell may bring
some hazardous conditions to area beaches during the day Wednesday
and Thursday. While the swell will only be around 14 feet at 14
seconds (producing a beach run up no more than about 18 feet), this
will be one of the first swells of the season. This means most areas
beaches have a shallower grade that has formed over the summer,
which may make waves especially dangerous and unexpected. Take extra
care if on local beaches this week. /JHW

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Wind Advisory from 11 AM Tuesday to 1 AM PDT Wednesday for
     CAZ101-102-104>106.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Gale Warning from 11 AM to 11 PM PDT Tuesday for PZZ450.

     Small Craft Advisory from 11 AM to 11 PM PDT Tuesday for
     PZZ455.

     Gale Warning from 8 AM to 11 PM PDT Tuesday for PZZ470.

     Small Craft Advisory from 8 AM to 11 PM PDT Tuesday 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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see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png