911
FXUS66 KEKA 180700
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1200 AM PDT Tue Aug 18 2026

.KEY MESSAGES...
* Smoke remains over areas outside of the marine layer due to local
  and distant wildfires.

* Interior temperatures are expected to remain near normal through
  the first half of the week with highs in the low to mid 90s.

* Another trough is expected to bring below normal temperatures
  and the potential for a few thunderstorms late in the week.


&&

.SYNOPSIS...A series of upper level troughs off the West Coast are expected to
generally keep inland temperatures near normal. Persistent marine
clouds expected along the coast with some afternoon clearing. Late
in the week, a stronger trough will bring cooler inland temperatures
and even the potential for inland thunderstorms.


&&

.DISCUSSION...Tuesday the ridge is expected to build slightly
over the area. The marine clouds are expected to push back to the
coast in afternoon, but once again it may be hard to clear out
right at the coast for very long. Inland temperatures are
generally expected to be in the mid to upper 90s or even 100 in he
warmest valleys. Wednesday may start to see a few degrees of
cooling here and there, especially closer to the coast as the
marine layer may deepen slightly.

Thursday several more degrees of cooling are expected as an upper
level trough begins to approach the area. This will likely deepen
the marine layer.

Thunderstorms are possible Friday as the trough deepens and starts
to move past the area just off the coast. Currently, two of the four
ensemble clusters are showing some instability Friday afternoon.
Confidence remains low, but there is potential for thunderstorms.
This will be monitored. As this system moves by the area, winds are
anticipated to increase in the afternoon and evening over the
interior areas. This trough will also bring cooler temperatures on
Friday with most of the area remaining below normal. Saturday
temperatures are expected to remain below normal before starting to
warm up on Sunday. MKK


&&

.AVIATION...Widespread stratus continues to redevelop
along the coast early this morning with LIFR conditions expected for
coastal terminals. KACV and KCEC should drop to 1/4 mile
visibility at times. Tuesday, the models show some clearing in the
afternoon, but this looks like it will be only for a few hours in
the afternoon. VFR conditions are expected for interior terminals
with periods of high clouds.


&&

.MARINE...Wind driven waves/fresh swell remain somewhat larger,
around 6 to 8 feet at 8 seconds. A small southerly swell continues
around 3ft@17s.

High pressure briefly returns Tuesday and Wednesday which will
increase northerly winds to around 20 to 25 kt. Thursday and Friday,
another upper trough is expected to flow over NW CA causing winds to
diminish again with the potential for local southerly winds near the
coast. MKK


&&

.FIRE WEATHER...The main challenge for the fire weather forecast
is the potential for thunderstorms late in the week. Tuesday through
early Thursday, weak high pressure is expected to bring dry and
fairly stable conditions. Winds will generally be terrain driven
with with typical northwest breezes in the afternoon. Thursday night
into Friday, another trough is expected to approach the area. At
this point it is still hard to tell if the moisture instability and
lift will line up to get thunderstorms, but it is possible. This
will continue to be watched through the work week.
Also, this trough may bring some breezy winds in the afternoon on
Friday.

Smoke was impacting portions interior Humboldt as well as the
Trinity River Valley. Early this morning, smoke is expected to
spread back into southern Humboldt and more of the Trinity River
Valley.  MKK



&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 9 PM PDT Wednesday 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