473
FXUS66 KEKA 020737
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1237 AM PDT Sun Nov 2 2025

.SYNOPSIS...Dry weather expected today. Wet weather returns on
Monday. Strong storm to bring potentially damaging winds, heavy
rain and increased risk for urban and small stream flooding
Tuesday night and Wednesday. Rain and potential flooding impacts
to continue on Thursday before rain tapers off on Friday.

&&


.KEY MESSAGES...

- Light to moderate rainfall returns on Monday.

- Strong Atmospheric River to bring strong and damaging winds,
  heavy rainfall and a risk for urban and small stream flooding.

- Higher than normal tides next week with storm surge, promoting
  coastal flooding expected in Humboldt Bay-North Spit and
  Crescent City.

&&


.DISCUSSION...

Dry and quiet weather conditions expected today (Sunday Nov 2).
Breezy northwesterly winds are forecast to develop over the
coastal headlands in the afternoon as surface high pressure
strengthens in the wake of a cold front. Interior high
temperatures are expected to be generally in the 70`s. Any areas
that do have fog will likely be slow to clear and high temps may
be lower than forecast. For the coastal areas, after the morning
stratus, mostly sunny skies are expected, allowing highs to warm
to the low to mid 60`s.

Light to moderate rain will return mid to late morning for Del
Norte County and in the afternoon for northern Humboldt and
portions of northern Trinty on Monday as the next in a series of
fronts impacts the area with rain. This front should push
southward during the evening and overnight hours Monday and
provide modest amounts of rain to Mendocino and Lake Counties as
well. Generally, light to locally moderate rainfall and breezy to
gusty south winds are expected with this first system. The next
shortwave trough will rapidly approach on Tue and precipitation
will once again increase throughout by afternoon and evening Tue.

A second, stronger system will intensify Tuesday night into
Wednesday as a potent upstream trough deepens and a surface
cyclone spins up offshore in response. Ensemble means and
deterministic GFS and ECMWF remain in a good agreement with the
deep trough becoming negatively tilted by 12Z Wed. This will send
a plume of high PWATS and high IVT into NW CA. Ensemble means
indicate a moderate AR while control runs indicate a stronger
atmospheric river event. Heavy rainfall is probable.

Strong damaging south winds are also probable (60-80% chance) as
surface pressure gradient tighten Tuesday night and a low level
jet at 925mb up to 70 kts develops along the coast. A well-mixed
boundary layer near or along the surface front will allow for
higher momentum air to mix down to the surface. There is a 40-60%
chance of gusts greater than 40 mph for the lowest elevations
widespread. For higher elevations and coastal headlands, NBM
indicates a 60-90% chance for wind gusts greater than 55 mph in
Del Norte and Humboldt counties. ECMWF ensemble mean 6 hourly wind
gusts are over 50 mph for the Del Norte Coast, specifically CEC
and over 40 mph for the greater Humboldt Bay area, ACV, EKA and
FOT. There are more extreme members from 55-70 mph in the ECMWF
distribution. Stronger wind gusts over 60 mph are highly probable
over the coastal mountains. A wind advisory will be necessary
while a high wind warning remains less certain (less than 50%
chance). Gusts over 55 mph is a sure thing for many of our wind
prone ridges and venturi-effect RAWS, specifically in the King
Range.

Regarding precipitation, substantial rain is expected for much of
the area Tuesday through Thursday, with the heaviest rates likely
Tuesday night into Wednesday. The probability of 6 hours
precipitation greater than 1 inch is 40-70% for Del Norte and
Humboldt counties from 10 PM Tue to 10 AM Wednesday. While 25-40%
for Mendocino and Trinity counties, and limited to 10-15% chance
for Lake County. Colder temperatures aloft behind the frontal
passage could support greater instability with heavy rain showers
and possibly thunderstorms continuing Wednesday afternoon and
evening or into Thursday. There is a fairly large spread in
precipitation estimates. Comparing the low end and high end
amounts (25th and 75th percentile) for 48 hour precipitation (4 AM
Tuesday to 4 AM Thursday). The high-end amounts from NBM (75th
percentile) for 48 hr of precipitation (4 AM Tuesday to 4 AM
Thursday) indicates 2.5 to 4.0 inches in Del Norte, Humboldt and
Trinity counties, with locally up to 4.5 inches over exposed
ridges. While 1.5 to 2.5 inches for Mendocino and Lake counties,
with heaviest along the coast. The low end precipitation (25th
percentile) suggest 1.0 to 2.50 inches, with locally up to 3.0
inches over the southwest windward facing terrain. Details will
become clearer in the coming days. This an unusually strong
AR event for early November and will need to be watched for
the possibility of urban and small stream flooding.

Another plume of moisture will take aim on the Pacific NW Thu-Fri
and bring another round of moderate to locally heavy rain to NW CA.
There are considerable timing difference with large spreads in 12-24
hour rain amounts. Once again urban and small stream flooding
will be possible as well as rock and mudslides in steep terrain.
A break in the parade of storms is forecast later on Friday into
Saturday as the flow amplifies in advance of another trough that
is forecast to dig over the central Pacific. This next trough may
bring more light to moderate rain as early as Sat. The frontal
boundary may stall offshore and take til Sun to arrive.

&&

.AVIATION...06Z TAFs...A weak front continues to traverse Northwest
California bringing IFR to LIFR conditions and light rain. Light
rain and IFR/LIFR conditions will persist for KACV through very
early Sunday morning as the front moves southeast. The front has
already moved out of KCEC with ceilings lifting and visibility
improving. The marine layer is expected to deepen in the wake of the
weak front and last through Sunday morning. IFR to LIFR conditions,
with areas of fog will linger longer for the interior and areas
south around Fort Bragg. Northerly winds will increase behind the
frontal passage. UKI is currently forecast to remain VFR with no
precipitation expected. Some soundings depict lower level moisture
entering the valley. The main threat for stratus intrusion will be
if the marine layer deepens enough to spill over from the west, but
confidence is low that this will occur. JJW/JLW

&&

.MARINE...The large swell that peaked between 13 to 16 feet at 16 to
18 seconds Saturday afternoon will continue to slowly subside into
Monday. A smaller reinforcing NW swell will then begin to move in
Monday. Northerly winds will increase early Sunday morning behind a
weak front. Gusts up to 30 kts are forecast by early Sunday morning
for mainly the outer waters beyond 10 nm. Combined sea heights from
the short period seas and fading WNW swell may near 14 ft Sunday.

The northerly winds will quickly ease late Sunday. An area of low
pressure will clip the waters Monday. Southerly winds will gust up
to 30 kts Monday and into Tuesday for a small portion of the
northern outer zone 470 as it passes. A strong frontal system will
begin moving in Tuesday when southerly winds quickly strengthen.
Strong Gale conditions are likely, with Storm force gusts over 50
kts possible and forecast Tuesday night and Wednesday morning.
JJW/JLW

&&

.BEACH HAZARDS...The large, long period WNW swell continues to
subside early Sunday morning. The sneaker wave risk will come to
an end early Sunday morning as the wave energy decays.

&&

.COASTAL FLOODING...Starting on Tuesday, astronomical high tides will
exceed 8 ft at the North Spit tide gauge. The highest tides, at around
8.5 ft will occur in the late mornings through midday on Thursday
and Friday. Moderate to strong southerly winds are forecast through
this timeframe, and will further contribute to a positive tidal
anomaly. Water levels may reach 10 ft at North Spit when high
tides align with the strong southerly winds. Currently, the strongest
southerly winds are forecast Wednesday morning. Expect Coastal
Flood Advisory issuance, with the possibility of a Coastal Flood
Warning if confidence increase of the southerly wind anomaly.
JJW/JLW

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Beach Hazards Statement until 4 AM PDT Sunday for CAZ101-
     103-104-109.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 AM PDT Monday for PZZ450-455-
     470-475.

&&

$$

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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