605
FXUS66 KEKA 030801
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1201 AM PST Mon Nov 3 2025

.SYNOPSIS...Rain is expected to return this afternoon and evening
for Del Norte and northern Humboldt and then spread southward
overnight. Risk for strong and damaging wind gusts will increase
late Tuesday afternoon and persist through early Wednesday morning.
Widespread heavy rain will increase the risk for urban and small
stream flooding late Tuesday night and Wednesday. Periodic rain
is expected to continue into Friday morning before rain tapers
off later on Friday into Saturday.

&&

.KEY MESSAGES...

- Periods of moderate to heavy rainfall and gusty south winds
  returns on Monday.

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

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

- Periods of rain expected to continue Thursday through Thursday
  night and then taper off Friday through Saturday.

.DISCUSSION...

Wet and unsettled weather returns this afternoon and evening
for Del Norte and Humboldt as the next in a series of fronts
with high PWATS impacts the area with rain and gusty south winds.
This first system will be driven by a compact surface low
swinging northeastward toward the Oregon Coast this afternoon.
Southerly winds will increase along the coast ahead of the
frontal boundary Monday morning. Strong southerly winds are
forecast to develop over the coastal headlands and exposed ridges
in Del Norte and Humboldt counties in the afternoon through early
evening. Gusts from 35 to 45 mph is expected, especially in Del
Norte County. HREF ensemble mean has peak wind gusts near 40 mph.
High- resolution models suggest a period of moderate to heavy
rainfall arriving late afternoon for Del Norte and early evening
for Humboldt. Extreme hourly rates over 0.50in/hr over the Del
Norte Mountains this afternoon and over the King Range this
evening. Models continue to consistently show front and plume of
moisture sagging southward into southern Humboldt and NW Mendocino
overnight. The boundary eventually stalls by early Tuesday.
Southeastern Mendocino and southern Lake may only get a few
hundredths or a trace of rain by 4 AM.

The next shortwave trough will rapidly approach on Tuesday and
precipitation will once again increase throughout from south
to north during the morning and afternoon on Tuesday. A second,
stronger frontal 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 Wednesday. This
will send a plume of high PWATS and high IVT into NW CA. Ensemble
means indicate a long duration moderate AR with a shorter duration
of strong AR conditions. Widespread heavy rainfall is highly
probable. Isolated storms may also also occur and if deep
moist convection develops, rates over 1 in/hr may occur.

Strong damaging south winds are also probable (60-90% chance) as
surface pressure gradient tightens 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.
For higher elevations and coastal headlands, NBM indicates a
60-90% chance for wind gusts greater than 45 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
to 50 mph for the greater Humboldt Bay area, ACV, EKA and FOT.
There are more extreme members from 60-75 mph in the ECMWF
distribution. Stronger wind gusts over 55 mph are highly probable
over the coastal mountains. A high wind watch has been issued as
this appears to be a highly anomalous wind event for this time of
year. It may end up as a wind advisory for the lower elevations,
however would not be surprised if some the higher elevations
venturi-effect RAWS gusts over 70 mph, specifically in SW
Humboldt in the King Range. Otherwise, gusts from 35-55 mph
appears more likely for the population centers. Winds this
strong can still rip branches off trees and may even bring a few
weaker trees down.

A watch for urban and small stream flooding may also be necessary
Tue night into Wed. Models remain consistent with heavy rain
increasing Tue night into Wed morning. HREF and individual CAMS
should shed more light on the rain intensity. Global models have
been hitting this hard for the last 5 to 7 days, just the timing
has varied.

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. Once again there will be a risk for urban and small stream
flooding as well as rock and mudslides in steep terrain. A break
in the rain is forecast later on Friday into Saturday as the mid
level 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 or slow down and take til Sun or Mon to arrive.

&&

.AVIATION...06Z TAFs...Diurnal drying, and increasing southerly
winds continue to inhibit most fog development outside of the wind
protected interior valleys into early Monday. Shallow stratus and
potentially brief fog visibility is forecast to increase along the
coast early Monday morning as southerly winds strengthen. KACV has
already experienced periods of shallow fog early this morning.

Southerly to southeasterly winds will continue to strengthen early
Monday morning. These winds will be initially stronger over Del
Norte County, where there is the lowest probability for IFR or lower
CIGS/VIS into the early morning. The winds will be slower to
increase farther south along the North Coast. However, winds will
increase enough early to mid Monday morning to mostly prevent
lasting fog formation at ACV.

There is some indication that a shallow band of stratus could advect
up the Russian River Valley and into UKI early Monday morning from
the southerly flow. As of 06z Monday, stratus has not formed around
KSTS and winds remain calm. HREF indicates a 20% chance for ceilings
below 1000ft at KUKI by 13z or 14z. JJW/JLW

&&

.MARINE...

A large, long period WNW swell will slowly subside over
the next few days. Northerly winds will trend much lower and
continue to shift more southerly into Monday morning. Combined sea
heights of slightly over 10 feet will continue from the short
period seas and fading WNW swell.

An area of low pressure will clip the waters Monday. This system has
trended farther south increasing the magnitude of southerly winds
for our waters. Winds are expected to gust to Gale strength Monday
afternoon and evening for the northern outer zone 470 as the low
clips the waters. A Gale Warning has been applied to this zone for
Monday.

A strong frontal system will begin moving in Tuesday when southerly
winds quickly strengthen. Strong Gale conditions are forecast, with
Storm force gusts over 50 kts Tuesday night and Wednesday morning.
Short period seas will build to 15 to 17 ft Wednesday in response to
the Storm force winds. A large post frontal westerly swell will then
build in Thursday as southerly winds increase again from a secondary
trough. Gale criteria may be met from this second system. JJW/JLW


&&

.HYDROLOGY...

Periods of locally heavy rain late this afternoon through tonight.
Widespread heavy rain expected late Tue into Wed and potential
for urban and small stream flooding will increase. More rain is
probable for Del Norte and Humboldt Thu and Fri, but influx of
moisture appears somewhat lower. This will need to be watched for
minor flooding too. All main stem rivers are forecast to remain
below monitor/action stage through at least Wed morning.

&&

.COASTAL FLOODING...

Starting on Tuesday, astronomical high tides will approach or
exceed 8 ft at the North Spit tide gauge. The highest tides, at
around 8.5 ft will in 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, but
a slightly higher tide is forecast Thursday. Expect Coastal Flood
Advisory issuance, with the possibility of a Coastal Flood
Warning around Humboldt Bay if confidence increase of the
southerly wind anomaly. The high tides, heavy rainfall, and tidal
anomaly may require an expansion of an advisory along much of the
coast Wednesday and Thursday. JJW/JLW

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     High Wind Watch from Tuesday afternoon through Wednesday
     morning for CAZ101-103-109.

     High Wind Watch from Tuesday afternoon through Wednesday
     afternoon for CAZ102-104>106-110.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 7 PM PST Monday for PZZ450.

     Gale Watch from Tuesday morning through Wednesday morning
     for PZZ450-455.

     Small Craft Advisory until 3 PM PST Monday for PZZ455-475.

     Small Craft Advisory until 1 PM PST Monday for PZZ470.

     Gale Warning from 1 PM to 9 PM PST Monday for PZZ470.

     Storm Watch from Tuesday afternoon through late Tuesday
     night for PZZ470-475.

&&

$$

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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