838
FXUS66 KEKA 110824
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
124 AM PDT Sat Oct 11 2025

.SYNOPSIS...Colder air aloft will bring the potential for frost and
across the interior valleys this weekend. A colder storm system is
forecast early next week, and will bring additional rainfall and the
potential for some mountain snow.



&&

.DISCUSSION...After an active Friday morning with several non
routine products issued by our superteam/day crew (ZVS & RPA),
isolated to scattered stratiform precipitation will ease by this
evening. Most of the accumulation today will be towards the Oregon
border in Del Norte and Northern Humboldt with lighter accumulation
in the rest of the CWA. Satellite imagery with isobar overlays and
lightning detecting products, show a Meridional flow with a slight
shortwave feature near shore, likely the remnants of the low
pressure on the back side of the rotation displaying frontolysis as
a few lightning strikes but overall a frontal decay near the coastal
Oregon border.

The aforementioned trough will move inland over the Pacific
Northwest and Northern California this weekend. Lingering showers
are expected to taper off this evening. Followed by a period of
relatively drier weather with 10-30% chance for sprinkles or a few
hundredths of an inch will follow in a cold airmass Saturday night
and Sunday.

Overnight temperatures will trend much lower through the weekend
beyond the passage of a cold front. Frost and freezing temperatures
are currently forecast for the portions of the interior. How cold it
gets will be highly dependent on the amount of clearing/drying that
happens. The upper low will be slow to depart the region before the
next low begins its quick descent. Cloud cover and lingering showery
weather would moderate some of the cold subfreezing overnight lows,
with clearing out likely through the rest of the weekend.

Ensemble and deterministic models are in a good agreement with a
colder storm swooping down across the area on Monday. There still
some uncertainties in the location of the low. Additional rainfall
and some mountain snow look probable based on ensemble and cluster
analysis. There is currently a 30-50 percent chance for 24 rainfall
over an inch from 5 AM Monday through 5AM Tuesday, with the highest
chances in Mendocino and Lake counties, as well as southern
Humboldt. Colder airmass aloft will support lowering of the snow
levels to near 5500 feet early Monday. /ZVS /EYS


&&

.AVIATION...(06z TAFs)...The low pressure system will continue east
through this TAF period. Post frontal showers are expected early to
late Saturday morning with showers diminishing into Saturday
afternoon. Low clouds may be possible for interior valleys, that
received rainfall, early Saturday morning. VFR conditions with
periods of MVFR conditions are expected through the TAF period.


&&

.MARINE...Light to moderate breezes will slowly turn northerly
throughout Saturday as the upper level low continues east. Winds
will increase again out of the north on Sunday behind the departing
low pressure system. Small craft conditions are forecast for south
of Cape Mendocino Sunday into early Monday. Seas will be dominated
by a northwesterly fresh swell before the northerlies increase
resulting in some steeper seas, especially south of Cape Mendocino,
Sunday into Monday. Another low pressure system will slide down the
coast Monday into Tuesday bringing a quick period of light
southerlies to some of the waters before the northerlies return. /RPA


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Frost Advisory until 9 AM PDT this morning for CAZ107-108-
     110-114.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from 11 AM to 11 PM PDT Sunday for
     PZZ455.

     Small Craft Advisory from 3 AM to 11 PM PDT Sunday 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