447
FXUS66 KEKA 122154
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
154 PM PST Wed Nov 12 2025

.SYNOPSIS...A moderate atmospheric river will impact the area over
the next 36 hours with the greatest wind and rain focused in
Mendocino and Lake Counties. Conditions will clear for the end of
the week with another round of light rain along the North Coast late
in the weekend.


&&

.DISCUSSION...

KEY MESSAGES:

 - Rain begins late Wednesday night and tapers off Thursday morning.
Locally heavy rain is expected late in the evening and overnight.

-Greatest risk of flooding in Mendocino and Lake Counties Thursday
morning. Flooding would be minor to moderate roadway flooding in
urban areas.

- Strong winds Wednesday afternoon and overnight. Wind gusts of 40
to 50 mph with locally higher gusts at wind prone ridges and coastal
headlands. Greatest winds along the Mendocino Coast.

WEATHER PATTERN OVERVIEW:

A moderate atmospheric river is quickly approaching the coast
Wednesday afternoon. As of 1 PM, the first bands of the system are
visible about 50 miles offshore with southeast winds already
starting to increase along coastal headlands.

Southeast winds will continue to increase through the evening and
peak early Thursday morning as a well defined surface front
approaches the area. Winds are most likely to be strongest along the
Mendocino Coast with most likely gusts of 50 to 60 mph, especially
around Pt. Arena. There remains uncertainty in storm location with a
slight chance (less than 20%) of the storm diverting northward.
There is little chance for high end potential with little chance
(less than 10%) of gusts over 60 mph anywhere but the highest
isolated peaks of the King Range. Most populated areas will most
likely see peak gusts of 30 to 40 mph.

The strongest rain will generally follow the wind. Moisture
advection (IVT over 1000) is impressive with the system but very
short lived. 2 to 3 inches of rain is most likely across Mendocino
and Lake Counties with only about 1 inch of rain in the more rain
shadowed areas such as Humboldt Bay and Crescent City. Rain amounts
may peak over 5 inches in some isolated high mountain areas in the
King Range and Trinity Alps. Snow levels in excess of 6000 feet will
inhibit any winter weather concerns.

Although rain amounts are generally only moderate, rainfall will
most likely occur over only a 6 to 10 hour period. Even following
ensemble mean guidance, that translates to sustained rain rates of
0.3 to 0.4 in/hr. High resolution models suggest reasonable
potential (20% chance) of rain rates enhanced up to 0.5 in/hr over a
long period of time. Such rates could generate urban and small
stream flooding alongside increased landslide risk. Any flooding
impacts will most likely quickly recede by early Thursday afternoon.
Areas further north along the coast are generally less prone to flood
and will see much lighter rain.

Some showers could linger Thursday evening into early Friday.
Additional rainfall will most likely be no more than 0.1 inches with
less than 10% chance of additional total rainfall over 0.2 inches. A
drier and cooler air mass will quickly build behind the front with
mostly clear skies by Friday afternoon. Another, weak rain event is
expected later in the weekend. Current rain amounts will most likely
be less than 0.5 inches, focused along the North Coast. Light
offshore flow and drier conditions behind that rain may bring some
of coolest night time conditions of the season so far to the coast
with a 60% chance of morning lows below 40 by mid next week. /JHW


&&

.AVIATION...18Z TAFs...Southerly winds will continue to increase
today as a strong frontal system moves in. A strong southerly jet of
50 to 60 kts through the 1500 to 2000 ft AGL level is also
developing. These winds will bring a risk for strong turbulence and
low level wind shear. Rainfall will increase tonight, and rates will
be moderate to heavy at times.

The heavier rainfall will be from Southern Humboldt, through Trinity
County, and southward through Lake County. Ceilings are generally
forecast to remain MVFR to VFR with the strong, warming downsloping
winds lifting CIGS heights. The heavier rainfall rates will bring
chances for TEMPO IFR CIGS and VIS. UKI is currently forecast to at
least TEMPO drop below 1700 ft AGL near 11Z Thursday with the
heavier rainfall rates.

The greatest risk for low level wind shear will from 3Z Thursday to
16Z Thursday. A cutoff low responsible for the winds will meander
off the coast Thursday, and a moderate risk for wind shear will
remain into Thursday evening for mainly Humboldt and Del Norte
counties where stronger southerly winds aloft will be slower to
subside. JJW


&&

.MARINE...Gale condition are underway in the waters as a strong area
of low pressures moves in. Southerly winds will quickly strengthen
this evening with Storm force gusts over 50 kts forecast into
Thursday morning. These higher caliber winds will surge into the
southern inner coastal waters around the cape and Mendocino coast
as well.

The area of low pressure will stall off the coast Thursday as it
weakens, and this will carry lingering Gale strength gusts over the
outer waters. Gusts up to 30 kts are forecast through Thursday night
before the low pulls away and fades. Winds and seas will quickly
subside through Friday afternoon. Seas will further drop Saturday as
the northerlies begin the strengthen some.

Steep and hazardous wind driven short period seas will develop,
reaching 13-15 ft by early Thursday morning. A longer period west-
northwest swell will also build in Thursday. Combined sea heights
will likely spike to around 19 ft late Thursday and into Friday
morning. A Hazardous Seas warning may be considered with further
confidence. JJW


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Wind Advisory from 2 AM to 7 AM PST Thursday for CAZ101.

     Wind Advisory until 7 AM PST Thursday for CAZ102.

     Wind Advisory from 7 PM this evening to 7 AM PST Thursday
     for CAZ103-107-108-110>113.

     Wind Advisory until 7 AM PST Thursday for CAZ104>106.

     High Wind Warning from 7 PM this evening to 7 AM PST
     Thursday for CAZ109.

     Flood Watch from 1 AM PST Thursday through Thursday morning
     for CAZ110>115.

     Wind Advisory from 10 PM this evening to 7 AM PST Thursday
     for CAZ114-115.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Gale Warning until 8 AM PST Thursday for PZZ450.

     Gale Warning until 10 PM PST this evening for PZZ455.

     Storm Warning from 10 PM this evening to 7 AM PST Thursday
     for PZZ455.

     Gale Warning until 7 PM PST this evening for PZZ470-475.

     Gale Warning from 3 AM to 3 PM PST Thursday for PZZ470-475.

     Storm Warning from 7 PM this evening to 3 AM PST Thursday
     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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For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png