969
FXUS66 KEKA 252215
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
310 PM PDT Fri Apr 25 2025

.SYNOPSIS...Showers activity will increase this evening. Scattered
to numerous showers across the area through Saturday, with
lingering showers through Sunday morning. Breezy northwest winds
will developed along the coast and exposed ridges Saturday through
Sunday. Dry and warming trend Sunday through mid next week.


&&

.DISCUSSION...A closed low center located just near 39N and 127W
continue to track southeast toward central California through
Saturday. This is promoting above normal moisture values across
across Northwest California, especially along the North Coast this
afternoon. Diurnal heating are promoting isolated showers are
already around the Yolla Bolly. There is some shallow instability
this afternoon with a cold air aloft over Trinity capable of produce
moderate showers bands. For the rest of the day, showers activity
are expected to increase in coverage this evening with increasing
low to mid level moisture as the aforementioned low moves closer.
Expect scattered to numerous showers across the area through
Saturday, with periods of moderate rain rates. Precipitation will
tapper off from north to south Saturday evening as the trough
eject the area, with lingering showers through Sunday morning.

Saturday`s high temperatures are forecasted to be 5 to 15 degrees
below normal. ECMWF Extreme Forecast Index (EFI) highlight highs
in the 60th-80th percentile below normal temperatures on Saturday,
especially for the interior areas in southern Humboldt, interior
Mendocino and Lake County. Overnight temperatures are expected to
remain in the 40s across the valleys due to lingering low level
moisture.

Breezy northwest winds will developed along the coast Saturday
afternoon through Sunday as a surface high pressure begin to
builds in and tighten the pressure gradient. Gusts from 25 to 35
mph are forecast for the coastal headlands and exposed ridges,
with strongest winds over the more prominent exposed terrain. HREF
probabilities indicates there is a 50 to 75% chance of wind gusts
greater than 30 mph for the North Coast Saturday evening, then
increasing chance up to 50% across the Mendocino Coast late
Saturday night.

Sunday, clearing skies are expected and temperatures will start
to warm back up again as a high pressure begin to builds in
downstream in the wake of the trough. Inland areas are expected to
see highs in the 60s. Areas of valley fog are expected to develop
Sunday night into Monday. High pressure continues to build in
through the week with highs around 80 for the inland areas by
Wednesday.

Ensemble clusters and deterministic models shows the high pressure
shifting eastward on Thursday. Most of the cluster members (78%)
suggest an upper level trough approaching the area next Friday. However,
there is uncertainties with the position of the low and if there
will be any impacts to our area. ZVS


&&

.AVIATION...Upper level low spinning around near 39N 127W will
continue to track southeastward toward central California tonight
through Saturday. Multi-layered cloud cover and moist air will
continue to wrap around the low center into the area tonight through
Saturday, resulting in mostly MVFR conditions. Periods of IFR
conditions are also expected for mostly coastal areas with a steady
low level NW flow and a shallow humid layer. The occurrence of wrap
around precipitation will increase the chance for IFR and MVFR
conditions outside the terminal aerodrome airspace. Surface pressure
gradients will begin to tighten on Saturday as the low tracks
southeastward while high pressure builds toward the NW California
coast. Gusty north-northwesterly winds and low level turbulence are
anticipated for coastal aerodromes, especially at KCEC, in the
afternoon. DB


&&

.MARINE...Wave spectrum remained heavily skewed toward shorter
period bands (less than 10 seconds) today. Multiple long and mid
swell groups from the SW and W were also present and contributing
much less to the total sea state which has been 4 feet or less. A
lighter NW wind regime (5 to 15 kt) is forecast to continue for
tonight and Friday with steep seas continuing on a downward trend.

Marine conditions are forecast to deteriorate this weekend and
remain hazardous into at least early next week. On Synoptic scale, a
weak and diffuse surface low over NRN California outer offshore
waters (150-250NM) SW of Cape Mendo is forecast to move
southeastward tonight through Saturday into central California
offshore waters. Surface high pressure is forecast to build toward
the Pac NW Saturday afternoon resulting in a tighter pressure
gradient over NW CA coastal waters. Model derived 10 meter winds
continue to show variability with the rate of increase and location
of the speed max. Leaned toward the ARW and FV3 and the HREF mean
with strongest wind max over the northern waters around Pt St George
during the afternoon and early evening hours. Coverage and duration
of gale gusts over 34kt appears limited for a gale warning at this
time. Steep northerly wind waves will build during the late
afternoon and peak around 10 ft around 9 seconds. This will be
borderline for a low end hazardous seas warning for primarily the
outer waters or 10 to 60NM from shore into Sunday morning. Our
spring time northerly wind regime featuring locally strong northerly
winds around Pt St George and in the lee of Cape Mendo as well as
steep northerly waves near 10 ft will most likely stick around on
Sunday into early next week. DB

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from 3 PM Saturday to 9 AM PDT Sunday
     for PZZ450-455-470-475.

&&

$$

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