153
FXUS66 KEKA 172217
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
317 PM PDT Mon Aug 17 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
  through 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...A weak trough is moving through the area this
afternoon and bringing some fairly thick high clouds. These are
moving out of the area. The CAMS are showing some light showers
developing in Siskiyou county, but moving north and away from the
area. Tonight the marine is expected to return, although it isn`t
expected to be particularly deep. 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 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 starts 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. So confidence remains low, but there is the potential
for thunderstorms and will continue to message the threat. As this
system moves by the area winds are expected 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...The marine clouds have pushed off the coast from KCEC
and KACV, but this is expected to shortlived. The Mendocino coast
continues to be cloudy. Tonight widespread stratus is expected
along the coast again and this is generally expected to be LIFR in
most areas. There is the potential for KACV and KCEC to drop to
1/4 mile at times overnight. Tuesday the models show some clearing
in the afternoon, but this looks like it will be only for a few
hours in the afternoon. MKK

&&

.MARINE...Northerly wind have diminished this afternoon and are
around 15 to 20 kt. The 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. The northwest winds this afternoon have
pushed some of the smoke out of Southern Humboldt and out of the
Trinity river valley of Big Bar. Tonight smoke is expected to
spread back into southern Humboldt and more of the Trinity river
valley. Tuesday is generally expected to see similar smoke
conditions to today.  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