James Irvine Trail, California Weather Forecast Discussion

435
FXUS66 KEKA 040710
AFDEKA
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1210 AM PDT Sat Oct 4 2025
.SYNOPSIS...
Drier and warmer weather is forecast for the next several days as
a ridge of high pressure builds over the West Coast. The next
chance for rain may be late next week as another trough approaches
the region.
&&
.DISCUSSION...
The trough and upper low that brought rain showers to Northwest
California is beginning to move inland allowing for drier air to
filter over the area from the north. This drier air and northerly
flow has ended the shower activity and we should go into a drier
pattern for the next several days. A shortwave diving south on the
west side of the departing low may bring some cloud cover and a few
showers to areas just north of Del Norte County Saturday into
Saturday night. However, as the shortwave passes to the south, east-
northeasterly flow is forecast to develop resulting in dry, offshore
winds and warming temperatures aloft. The vast majority of model
guidance is indicating ridging will build over the region for early
next week with temperatures warming to near normal across the region
Sunday through Tuesday.
The next weather challenge comes later in the week when an upper low
may cut-off from the flow off of the Northern California coast. The
operational runs of the GFS and ECMWF are both predicting this low
to be present off our coast around the 9th or 10th. Being this many
days out, however, it`s essential to check the ensemble cluster
analysis to see if the operational runs are outliers despite their
consistency. And lo and behold (no pun intended), the ECMWF
operational run is only one of 16% of the ECMWF ensemble indicating
this outcome. The other 84% either takes the low down the coast as a
slider or never cuts the low off at all. The GFS ensemble on the
other hand, and also the Canadian ensemble, is much more
confident in the cut-off low solution with about 90% in this camp.
Thus, despite the operational run agreement, there remains
uncertainty as to the final trajectory of the low pressure system.
Regardless, rain chances will be on the increase late week and
depending on the lows progression, could bring widespread wetting
rains to the region and a period of gusty south winds near the
coast. If the cut-off low solution develops, the upper levels may
be quite cold resulting in steep lapse rates and the potential for
thunderstorms. RPA
&&
.AVIATION...
Low clouds and stratus are currently visible on satellite over
Humboldt County and areas off the coast. MVFR ceilings are being
observed at ACV with this deep marine layer. A weak marine
inversion along with offshore flow may keep the Del Norte and
Mendocino coasts clear tonight, though some brief impacts are
possible near sunrise. Generally, ceilings are forecast to remain
MVFR with brief periods of IFR. Inland areas outside Humboldt will
largely remain VFR overnight into Saturday. Winds are likely to
be gusty again along the coast, with afternoon gusts nearing or
exceeding 20 kts. Higher gusts are possible at CEC. JB
&&
.MARINE...
Northerlies have continued to increase early this morning and
confidence is growing for gale force gusts in the southern waters
(south of Cape Mendocino) starting this morning. These are likely
to continue into the afternoon and into Sunday. Elsewhere, peak
gusts today range between 20-30 kts. Tonight into Sunday morning,
winds increase further with gales briefly possible in the northern
outer waters. Nearshore waters are unlikely to see gales, except
around Cape Mendocino, but steep seas propagating nearshore from
these winds are possible. Generally, the sea state will be
dominated by short period seas of 5-9 ft through the weekend. High
pressure weakens by Sunday afternoon into early week, and winds
will likely ease. JB
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 11 AM PDT Sunday for PZZ455.
Small Craft Advisory until 3 AM PDT Sunday for PZZ470.
Gale Warning from 3 AM to 11 AM PDT Sunday for PZZ470.
Small Craft Advisory until 3 AM PDT early this morning for
     PZZ475.
Gale Warning until 11 AM PDT Sunday for PZZ475.
&&
$$
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

NWS EKA Office Area Forecast Discussion