149
FXUS66 KEKA 052244
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
244 PM PST Fri Dec 5 2025

.SYNOPSIS...Light rain possible for Humboldt and Del Norte late
this afternoon and evening. King tides combined with tidal anomaly
will continue to bring the threat of coastal flooding in low-
lying areas around Humboldt Bay Saturday. A series of frontal
systems moving north of the area will bring a chance of light rain
across the northern portion of the area through the weekend.


&&

.DISCUSSION...IR satellite imagery depicts a cold front just north
of the area, while downstream flow from the high pressure over
Northeastern Pacific is bringing increasing moisture. A deep
marine layer and stratus continues to blanket much of Del Norte
and Humboldt counties. Elsewhere, generally sunny to partly cloudy
sky conditions are observed. The Mckinleyville profiler indicates
the marine layer depth is up to 3,000 feet MSL. Otherwise, stratus
is expected to lift during the evening as the cold front approaches
from the north and destabilize the marine layer. Light rain or
sprinkles are expected for the northern portion of the forecast
area this evening, especially for Del Norte and Humboldt counties
after 4 PM this afternoon. In addition, breezy northwest winds
will continue over the coastal headlands and exposed ridges this
evening and into Saturday.

High pressure continues to slowly weakening and "flattening",
while a series of shortwaves trough and frontal systems embedded
to the Aleutian Low continues to move toward the Pacific Northwest
this weekend. Northwest flow aloft will bring additional light
showers across Del Norte and Humboldt counties on Saturday. On
Sunday, another shortwave and frontal system is expected to move
north of our area. The flow aloft will become more zonal, bringing
additional chances of light rain across the northern portion,
especially for Del Norte and northern Humboldt counties.
Elsewhere, partly to mostly cloud skies is expected to continue.

The 500 mb ridge appears to slowly build back early next through
mid next week. WPC ensemble clusters do show about an even split
(50%) of clusters that are "drier" (at least for the North Coast)
than the grand ensemble mean. The ensemble mean is by no stretch
very wet with 0.10-0.25 inches of rain in 24 hours everyday from
Monday through Wednesday, mostly for Del Norte. It could be wet
or it could be dry or both. Stay tuned. -ZVS


&&

.AVIATION...(18Z TAFs)...Drizzle moved through this morning for
Humboldt and Del Norte Counties, bringing LIFR to IFR conditions to
the coastal terminals. After a brief lull, LIFR conditions have
returned to the coastal terminals. A frontal passage accompanied
with drizzle or light rain late this afternoon will continue IFR to
LIFR ceilings and bring lowered visibility. Lingering light showers
or drizzle will ease overnight. Southeast flow ahead of another
frontal passage to the north may aide in lifting ceilings and
visibilities around sunrise. For areas to the south and east,
including UKI, only a few high clouds are expected with generally
light winds. There is around a 30% chance for IFR to MVFR stratus
impacts before and around sunrise at UKI Saturday. Any low clouds
and fog will lift and scatter shortly after sunrise. JB


&&

.MARINE...Winds and seas continue to ease north of Cape Mendocino as
a weak front moves through the area. South of Cape Mendocino, breezy
northerly winds continue through the evening. Peak gusts of 20-30
kts are possible south of the Cape this afternoon and evening. Steep
wind waves of 5-8 ft are combining with a decaying mid-period swell
of 3-4 ft. Winds and steep seas ease overnight. Generally light
winds are forecast this weekend, with south winds forecast north of
Cape Mendocino and west-northwest winds forecast south of the Cape.
Despite light winds, seas will elevate as a mid-period northwest
swell fills in Saturday. This will peak at around 7-9 ft at 12
seconds. Wave heights peak Saturday night and early Sunday morning,
and combined seas could briefly reach or exceed 10 ft. Seas subside
Sunday and Monday as this swell decays. Light winds continue into
early next week, but seas will remain elevated as a series of mid-
period northwest swells fill in from systems to the north. JB


&&

.COASTAL FLOODING...King tides are predicted to continue this
weekend. High tides are forecast to be at 8.63 feet at the North
Spit tide gauge at around 11:44 AM local time. High tides
combined with surge and tidal anomaly will result in water levels
between 8.9 to 9.2 feet MLLW (Mean Lower Low Water). Minor
coastal flooding around Humboldt Bay, including King Salmon and
Jackson Ranch Road in the Arcata Bottoms, will be likely between
10 AM and 1 PM. A Coastal Flooding Advisory will be in effect
from 10 AM to 1 PM on Saturday. High tides are predicted to be at
8.24 feet at 12:35 PM on Sunday. At this point, coastal flooding
looks marginal for Sunday with high tides diminishing. -ZVS

-ZVS


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Coastal Flood Advisory from 10 AM to 1 PM PST Saturday for
     CAZ103.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Coastal Flood Advisory from 10 AM to 1 PM PST Saturday for
     PZZ415.

     Small Craft Advisory until 11 PM PST this evening for
     PZZ455-475.

&&

$$

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