Potter Valley, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

384
FXUS66 KEKA 231014
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
214 AM PST Tue Dec 23 2025

.SYNOPSIS...The next round of heavy rain and strong wind returns
Tuesday evening through early Wednesday. There may be a brief
break in the weather Wednesday. More heavy rain, mountain snow,
and strong winds are expected Wednesday night and Thursday. Drier
weather is finally possible by the weekend.

KEY MESSAGES...
- Strong winds to Very Strong Winds Tuesday night into early
  Wednesday.

- Additional moderate to heavy rain likely Tuesday through early
  Wednesday.

- Additional heavy rain and strong winds possible Wednesday night
through Friday.

- Mountain snow above 4000 ft possible Wednesday through Friday.

DISCUSSION...

..Tuesday through Wednesday...


&&

.DISCUSSION...An upper level trough well off the west coast is
deepening. A strong shortwave rotating around the base of it will
spin up a surface low. There is still some disagreement in how
strong this will be and where it will track. The GFS and the NAM
both keep the low off the coast, but the GFS moves it onto the
Oregon coast while the NAM moves it up along the west coast. The
NAM and the GFS both show it dropping around 24 MB in 24 hours
which would make it a bomb cyclone. Both models show 925 MB winds
of 70 to 80 kt over the waters with 60 to 80 kt moves aloft over
the land areas. This will likely produce gusts of 50 to 70 mph
over the higher terrain, channeled areas and the coastal areas.
These winds will likely only last a few hours with this fast
moving system. There is still quite a bit of uncertainty on where
this low will track, but a majority of the deterministic models
show it moving up off the coast. The HRRR and the ARW move the low
inland farther south and start it weakening sooner. Generally
favor the solution with the low off the coast. When there are
rapidly deepening lows the models tend to underdo cyclogenesis.
This tends to allow lows to move faster and more to the left than
predicted by the models. So have upgraded to high wind warnings
for northern Humboldt and Del Norte counties.

A band of rain is currently moving north across the area out ahead
of the trough. This is generally expected to bring a quarter to
three quarters of an inch of rain through the day. The rain may
let up at points in the day before the main round of rain
associated with shortwave and strong surface low arrives mid to
late Tuesday afternoon. The ensembles show IVT values of 700
kg/m/s in the south to around 500 kg/m/s in the north. Like the
winds there is a lot of uncertainty on where the heaviest rain
will be. There are some model solutions that keep the heaviest
rain off the coast. For details on the flooding potential see the
hydrology section. The rain and wind is expected to diminish
fairly quickly during the day on Wednesday leaving a general break
in the weather on Wednesday. MKK

..Wednesday night through the weekend...

The upper level trough off the coast starts to deepen again and
then start to become a cutoff low. The models differ on how deep
it gets and the location of it. But some of the models show
the low bombing out. This has the potential to bring strong winds
once again. It looks like stalls out off the coast around 12Z
Thursday and then starts to fill. The big question is where
exactly this low stalls out and where it goes when it does stall
out. The winds are expected to peak Thursday morning, but could
remain strong through the day Thursday and possibly into Friday.
The precip amounts look lower Wednesday night through Friday
morning, especially in the north.

Rainfall amounts again look heavier in the south. IVT values are
lower with this system, but may last longer. They range from
around 250 to 500  kg/m/s, lowest in the north.

Cold air moving in from the deep trough could support lower snow
levels and greater instability. Snow levels may drop further to
3500- 4000 ft. The cold air aloft could support small hail showers
and isolated thunderstorms along the coastal areas Thursday and
Friday. Total snow amounts of 2-3 ft through Friday is possible at
Scott Mountain pass, while up to a foot is possible above at the
highest passes of Highway 36 (around 4000 ft), depending on how
much the snow levels lower. This colder air aloft will also bring
the potential for thunderstorms and possibly some small hail near
the coast through the day Thursday.

Friday the models are in general agreement that the low will
start to move out of the area. High pressure is expected to start
to move into the area bringing a break in the rain and wind for
the weekend. The valleys will likely see widespread fog and low
clouds each night and through at least the morning. MKK/JB

&&

.AVIATION...
-Very strong winds at the surface and aloft from an approaching
"bomb" cyclone will bring a high end threat for turbulence and low
level wind shear Tuesday night through Wednesday morning.

-CIGs and VIS will deteriorate with moderate to heavy rainfall
Tuesday afternoon through Wednesday morning

-There will be only a very brief lull in strong winds and heavy
rainfall Wednesday morning before another strong system pushes in
Wednesday afternoon

.DISCUSSION...Light offshore winds maintained VFR over the coastal
terminals early Tuesday morning. Light rainfall spreading in from
the south will bring an increasing chance for MFVR CIGs today. The
wind protected inland valleys have the highest chance for IFR to
LIFR conditions through early Tuesday afternoon, such as UKI. Some
inland valley fog is also expected.

Moderate to heavy rainfall rates will spread over N CA late this
afternoon through Wednesday morning and will reduce CIGs and VIS to
more solidly MFR to periods of IFR.

A developing "bomb" cyclone will bring very strong winds aloft and
to the surface. 925 mb winds near 2000 ft AGL will likely range from
65 kts to over 80 kts later this afternoon through Wednesday
morning. This will bring a high end turbulence and low level wind
shear threat. There is some uncertainty with the exact track and
timing of these winds and associated heavy rainfall from this rather
compact and very deep area of low pressure as it tracks in from the
southwest.

Conditions will only very briefly improve Wednesday morning before
another strong system arrives Wednesday afternoon.  JJW

&&

.MARINE...Gale and storm force winds are forecast Tuesday night
into early Wednesday as a compact low accelerates northeastward
across the waters. Some of the models are showing winds as strong
as 50 kt sustained winds at the surface. These winds will be
relatively shortlived with this fast moving compact low pressure
that may reach bomb cyclone statues over the waters. Wednesday a
swell is expected to move in behind the winds. Waves are expected
to build to 10 feet at 10 seconds.

Another powerful storm is forecast to bring strong winds and
large steep waves Wednesday night. This storm may nearly reach
bomb cyclone status as well and may bring more storm force winds.
This one is expected to gradually weaken as it stalls out bringing
an extended period of strong to gale force winds through Thursday
night. Friday winds are expected to remain elevated then diminish
for the weekend. MKK

&&

.HYDROLOGY...The next rounds of rain are likely to produce
flooding impacts again across the area. While most ensemble
members show the heaviest rain heading to Mendocino and Lake
Counties again, significant rain is still likely for the entire
area. Small stream, creeks, and main stem rivers are all likely to
see impacts again. It is also possible the focus of the heavier
rainfall will shift north again. Currently the Russian River at
Hopland the Navarro river at Navarro are expected to reach flood
stage again. The Eel river and the Mad river are expected to be
close to flood stage, but not expected to exceed it at this time.
This will need to be monitored closely.

There is a short break in the rain Wednesday before the next
system Wednesday night. The break might only be 8 to 12 hours in
some areas. The rainfall amounts look lower with this system, but
with the ground saturated, any additional rain could be impactful
given there is little time for basins to drain. MKK

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Flood Watch through Friday evening for CAZ101>115.

     High Wind Warning from midnight Tuesday night to 9 AM PST
     Wednesday for CAZ101-103.

     High Wind Warning from 10 PM Tuesday to 10 AM PST Wednesday
     for CAZ102-105.

     High Wind Warning from 7 PM Tuesday to 8 AM PST Wednesday
     for CAZ104-106.

     Wind Advisory from midnight Tuesday night to 10 AM PST
     Wednesday for CAZ107-108.

     Winter Storm Watch from Wednesday afternoon through Friday
     evening for CAZ107-108.

     High Wind Warning from 7 PM Tuesday to 6 AM PST Wednesday
     for CAZ109>115.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Gale Warning from 2 AM to 8 AM PST Wednesday for PZZ450.

     Small Craft Advisory from 1 PM to 6 PM PST Tuesday for
     PZZ455-475.

     Gale Warning from 6 PM to 10 PM PST Tuesday for PZZ455-475.

     Storm Warning from 10 PM Tuesday to 6 AM PST Wednesday for
     PZZ455-475.

     Small Craft Advisory from 6 AM to 4 PM PST Tuesday for
     PZZ470.

     Gale Warning from 10 PM Tuesday to 10 AM PST Wednesday for
     PZZ470.

&&

$$

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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https://www.weather.gov/images/eka/zonemap.png