087
FXUS66 KEKA 080717
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1217 AM PDT Wed Oct 8 2025

.SYNOPSIS...An approaching trough will cool temperatures today.
Rain chances increase early Friday with much cooler conditions
likely. Cooler and perhaps wetter weather likely to continues into
the weekend and early next week.


&&

.DISCUSSION...Clear skies and dry conditions continues to bring
chilly low temperatures the interior areas. Slightly warmer high
temperatures on Tuesday and diminished offshore flow may keep
interior valley low temperatures a couple degrees warmer this
morning with generally high 30s or 40s forecast. Temperatures of 36
or less are unlikely and frost potential is low.

Low pressure will gradually fill in and deep trough dipping across
the eastern pacific will gradually come to dominate the weather
pattern through the end of the week. Flow switching onshore and more
marine air will generally allow for a marine layer to reform along
shore by this evening. Even with skies staying mostly clear, onshore
flow will most likely allow for coastal highs to return to the 60s.
Weakening high pressure will also allow the interior to cool back
into the 70s or 80s today. Building midlevel clouds will aid in
further cooling Thursday.

The trough continues to approach the area Thursday. South flow ahead
of the trough along with orographic lift support a few light rain
showers over Trinity County. CAMs are starting to show some support
this, but any rain amounts are expected to be minor. As the trough
moves inland Thursday into Friday, tropical moisture pulled in front
of the trough will enable at least light rain across the area. Rain
amounts remain uncertain. Deterministic models show only marginal
(0.6 to 0.8 in) precipitable water amounts. Still, consistent strong
southwest flow aloft may help make up for marginal amounts thanks to
consistent moisture transport and orographic forcing. NBM generally
seems to be erring on the high end of global ensembles with a wide
spread of 0.5 and 2.0 inches of rain along the north coast, most
likely beginning early Friday morning. A few thunderstorms are
possible which could bring localized higher amounts of rain to the
coastal areas. Generally less than 0.5 inches of rain is most likely
for the southern half of the area with a 25% chance of no
precipitation at all.

Lighter rain showers will continue into the weekend with only a 30-
50% chance of additional wetting rain each Saturday and Sunday,
mainly in the northern half of the area. Even without rain, cooler
and more moist conditions are likely to persist into early next week
with a good chance of widespread interior frost should conditions
dry out fast enough by Sunday and Monday.

There is increasing confidence among ensemble members for another
system approaching the area early next week. Confidence is currently
low on any impacts, but some models are showing a similarly cold, if
not colder, airmass moving overhead. This could bring more frosty or
freezing conditions in the interior into early next week. JHW/JB


&&

.AVIATION...(06z TAFS)...Mostly VFR conditions for the remainder of
Tuesday evening at the coastal terminals. Statistical guidance is
suggesting a reduction in flight categories (IFR) by 8-9z into early
Wednesday morning. With minimal cloud cover, radiation fog could
play a role for a reduction in visibility but as an upper level low
approaches, stratus is spreading from the south and offshore from
the north. A considerable blanket is forming off of the Sonoma and
Marin county coasts, at this point it looks as if advection inland
will be held to the shoreline. Threats to KUKI are minimal.

TAFs at KACV and KCEC do have lower visibility for the early morning
tempo`d just in case. Easterly winds at KACV and KCEC could keep
coastal stratus at a minimum overnight into Wednesday early morning.
Winds veer from the NW by noon Wednesday for the coastal terminals.
Light to calm winds at KUKI through the TAF period with southerlies
picking up by the afternoon Wednesday. /EYS


&&

.MARINE...Northerly winds will increase late tonight into Wed
behind a weak front forecast to pass in Pac NW on Wed. Greatest
coverage for gusts to 25-30kt is over the outer waters. Gusts to
30kt will be possible (40-60% chance) inside 10NM and downwind of
Cape Mendocino. Chances are are lower (10-20%) around Pt St George.
Steep northerly wind waves will also rebuild to 6 to 8 ft by Wed and
seas will once again become hazardous to small craft. Northerlies
will diminish and eventually turn southerly for the northern waters
on Thu. Southerlies will likely strengthen in advance of a front on
Friday. NBM probabilities are not very high around 15 to 25% for
gusts over 25 mph. Looking at the deterministic guidance, suspect
there will be higher gusts. Lack of a long southerly fetch may limit
the short period wave generation to only 4 to 5 ft from the SW.
There are indications from the GEFS and ECMWF ENS for stronger
northerlies to ramp up toward the latter portion of the weekend.


&&

.COASTAL FLOODING...The full moon has brought higher than normal
tides to the coastlines. The North Spit tide gauge is forecast to
reach 7.91 ft MLLW around 1 PM this afternoon. With the anomaly
added this would be around 8.80 ft MLLW, which could cause coastal
flooding to King Salmon and in the Arcata Bottoms by Jackson Ranch
Rd. Building northerly winds today may lower the anomaly
slightly, keeping below 8.8 ft at least for today. The tides are
forecast to be higher Thursday and Friday, reaching 8.03 ft MLLW
around 1:30 PM Thursday and 7.94 ft MLLW around 2:00 PM Friday.
Southerly winds ahead of the system may increase the anomaly
which could lead to minor coastal flooding. JB


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from 6 AM Wednesday to midnight PDT
     Wednesday night for PZZ470.

     Small Craft Advisory from 6 AM Wednesday to 6 AM PDT
     Thursday 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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