Porter Ranch, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

211
FXUS66 KEKA 252259
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
259 PM PST Thu Dec 25 2025

.SYNOPSIS...A mix of linear bands and cellular convective activity,
mountain snow and periods of strong to gusty winds will continue
through Friday morning. Shower and isolated thunderstorm activity will
gradually to diminish through the day on Friday. Drier and colder
weather is forecast for the weekend and should last into early
next week.


&&

.KEY MESSAGES...

* Strong to gusty winds, showers and isolated to scattered
  thunderstorms with locally heavy rain expected through Friday
  afternoon.

* Flood Watch remains in effect through Friday evening for
  Humboldt, Trinity, Mendocino and Lake counties.

* Winter Storm Warning for elevations above 4000 ft through
  Friday evening for Trinity County.

* Hazardous marine and coastal conditions expected through Friday
  morning.

&&

.DISCUSSION...Scattered to numerous showers and isolated
thunderstorms under a southwesterly wind flow aloft continues
impacting the region. Several lightning strikes and small hail
have been detected with the strongest thunderstorms. These showers
have been producing moderate to locally heavy rain during the
morning and early afternoon hours.

A negatively tilted shortwave trough is pinwheeling into Northern
California around a 982mb low pressure currently located just
near 42N 129W, just ~260 miles offshore of Oregon Coast. An
upstream mid-level jet and associated vorticity maximum will
approaches the NW California, specifically the Mendocino Coast
late this afternoon and evening. This will bring another peak in
winds and an enhanced in showers across the area. A line of
organized convection activity with heavy rain and/or thunderstorms
is expected to move from southwest to northeast across the region
with sudden, strong to gusty south winds from 30 to 50 mph late
this afternoon and evening. Heavy rainfall rates up of 0.30" to
0.50" per hour will be likely with these new rounds of heavy
showers and thunderstorms activity. The saturated soil conditions
along with strong winds will bring an increased risk of downed
trees, and will make it easier for tree to uproot. In addition,
there is the potential for isolated waterspouts near shore late
this afternoon/early evening as well.

A mix of linear bands and cellular convective activity is
expected to move across the area from southwest bringing an
additional peak in winds tonight into Friday. A brief burst of
strong to gusty winds is expected along a 45-60kts coastal barrier
jet (925mb) late tonight and early Friday. Strong south winds
from 40-50 mph are expected over the coastal headlands and exposed
ridges in Southwestern Humboldt, Mendocino and Lake counties,
with locally strongest gust up to 60 mph possible.

Snow level will likely drop to 3500-4000 ft tonight into Friday
as colder air aloft moves across the area. 48-hour total snow
amounts of 2-3 feet are expected through midday Friday. A brief
break of showers is expected this afternoon and early evening, but
travel over Scott Mtn Pass will be very difficult or impossible
if roads are now plowed.

The mid-upper level trough and associated surface low is expected
to move overhead Friday afternoon and shift east-souteast across
the area Friday night. Showers and thunderstorms activity are
expected to gradually diminish by afternoon and evening hours on
Friday, with lingering showers into Saturday.

High pressure is expected to start to move over the area on
Saturday bringing a break in the prolonged wet spell. Northerly
may be a bit breezy and gusty over ridges this weekend. The
valleys will likely see widespread fog and low clouds each night
and morning. Frost and freezing temperatures will also be possible
for the North Coast, especially Sunday morning. Cooler and drier
weather should last into early next week. This may be too
optimistic this time of year. Chances for more than 4 to 5 days in
a row of no possibility of precip is not high. In fact CPC 8-14
day outlook already has us back in a slight risk for heavy rain
and high mountain snow. /ZVS


&&

.AVIATION...An upper level low off the coast continues to have
showers rotating around it. There are some shortwaves that are
enhancing these showers periodically and bringing some thunderstorms
as well. This low has strong southerly winds ahead of it. Additional
shortwaves are expected tonight through Friday morning. Later this
afternoon or evening a shortwave is expected to push some stronger
showers north into Mendocino county and Ukiah through around 3Z on
the 26th. Late tonight it looks like another will bring enhanced
showers to the terminals. These showers will generally bring
increased wind gusts and brief periods of IFR conditions. Friday
afternoon the winds and showers are finally expected to start to
diminish. MKK


&&

.MARINE...The upper level low off the coast continues to bring
strong southerly winds to the waters, although they have diminished
slightly from earlier. Gales generally persist in most areas with
more storm force gusts in the northern outer waters. Some areas the
winds have dropped below gale force, but frequent showers will bring
gusts back up to gale force periodically. So have dropped the storm
warnings in all but the northern outer zones, but have added gale
warnings through Friday morning. This is continuing to product waves
of 12 to 18 feet. Tonight and Friday a west to northwest swell is
expected to move into the waters and build to around 6 to 12 feet at
12 to 14 seconds. The biggest waves are expected in the southern
waters.

Friday afternoon or evening the winds are expected to northwesterly
as the the low finally moves inland. Northerly winds of 15 to 25 kt
are generally expected through the weekend. Early next week it looks
like there will be a weak system breaking down the ridge and
bringing lighter winds. However, there is some uncertainty on the
timing of the system. Late in the week northerlies are expected to
return. MKK


&&

.HYDROLOGY...Moderate to locally heavy rain showers are expected
to continue across the area through Friday, with max rain rates
up of 0.30" to 0.50" per hour likely. Heavy shower could promote
minor flooding of smaller rivers, creeks and streams with poor
drainage will be possible with grounds saturated and all the water
going into run-off. Mad River at Arcata and Eel River at Fernbridge
could touch Monitor Stages Friday evening/night. Hopland could
also touch or exceed slightly minor flood stage (15% chance) on
Friday. Otherwise, all main stem river stages are forecast to
remain below Monitor or Action stages through Friday. /ZVS



&&

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

     High Wind Warning until 8 PM PST this evening for CAZ101.

     Wind Advisory until 8 PM PST this evening for CAZ102.

     Wind Advisory until 2 PM PST this afternoon for CAZ103.

     High Wind Warning until 2 PM PST this afternoon for
     CAZ104>106.

     Winter Storm Warning until 10 PM PST Friday for CAZ107-108.

     High Wind Warning until 10 AM PST this morning for CAZ109.

     Wind Advisory until 10 AM PST this morning for CAZ110>115.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Storm Warning until 3 PM PST this afternoon for PZZ450-455-
     475.

     Storm Warning until 11 PM PST this evening 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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see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png