115
FXUS66 KEKA 270857
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
157 AM PDT Thu Aug 27 2026

.KEY MESSAGES...
* Interior areas continue to see near to slightly below normal
  temperatures through this weekend.

* Coastal areas continue to see overnight stratus with afternoon
  clearing.

* Tropical moisture may bring a few showers to Mendocino and Lake
  Counties Friday morning.

&&

.SYNOPSIS...Generally mild, seasonable weather continues Thursday.
Tropical moisture arrives to the area Thursday night and Friday,
bringing a slight chance for rain showers to Mendocino and Lake
Counties.


&&

.DISCUSSION...An upper-level trough remains in place over the
Pacific Northwest. This has moderated interior temperatures with
highs in the high 80s to low 90s for most interior valleys. A weak
marine inversion in place has allowed for coastal stratus to clear
into the afternoons, but stratus will likely reform each evening and
continue overnight for the coming days. Coastal high temperatures
are forecast to be in the low to mid 60s as northwesterly afternoon
breezes return. A deep marine layer also brings overnight stratus
farther inland, which is moderating some fire weather concerns,
especially closer to the coast.

Thursday into Friday, moisture from the remnants of Tropical Storm
Iselle, currently off the coast of Mexico, will arrive to central
and northern California. Models are coming into better agreement on
the position and timing of the moisture.
Precipitable water values hover around 0.8" to around 1.0". Dry
lower levels will limit potential for any of this to reach the
ground, but a few sprinkles are possible in southern Mendocino and
Lake Counties Friday morning and early afternoon. Instability is
limited and thunderstorm chances are low (less than 5%). That said,
there are a couple models that do show stronger cells with slightly
more instability, so thunderstorm chances are nonzero but still very
low. Recent model runs have moved this moisture plume to be in a
more north-south orientation, which is also limiting moisture
coverage over the area in general and also limiting moisture to from
Thursday evening to Friday morning. By Friday afternoon, moisture
moves eastward. This will be watched closely as any increase in
instability could bring more confidence in thunderstorms.

This weekend, a trough in the Pacific Northwest rebuilds and is
modeled to be slightly stronger and farther south. This will
continue the moderated interior temperatures (high temperatures in
the 80s to low 90s), and possibly bring coastal drizzle overnight
and more persistent coastal stratus into the afternoons. Coastal
high temperatures are also forecast to drop into the high 50s to low
60s with this more cloudy pattern. Early next week, a stronger
trough drops from the Pacific Northwest. This is expected to bring
cooler temperatures across the area with most interior areas 5 to 10
degrees below average. Coastal drizzle or light rain is possible for
the Humboldt and Del Norte Coasts as well, but recent model runs
have been trending this moisture northward. /JB


&&

.AVIATION...Stratus and fog has redeveloped along the coast and
continues to expand into areas not yet cloudy as of this hour. Only
the Shelter Cove area north to Cape Mendocino may remain clear
overnight. LIFR ceilings and visibilities falling to below a half
mile will be possible into the morning hours with visibility
occasionally falling to a quarter mile or less. A weak marine
inversion should allow for the coastal clouds to mix out through
the morning hours, bringing a return to VFR by around midday.
Farther inland VFR will prevail through the forecast period. /RPA


&&

.MARINE...Northerly winds will increase over the next few days as a
trough moves inland and heat builds into the weekend. This will
result in an expansion of the small craft advisories into additional
areas Saturday into Sunday, particularly in the outer waters. Some
gusts to gale force will be possible late in the weekend but at this
time the gusts appear to be limited enough to not require early
heads-up of gale potential. Thus, small craft advisories will only
be issued at this time. The northerly winds will decrease quickly
early next week as another trough approaches the area.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from 9 AM Friday to 9 PM PDT Saturday
     for PZZ455.

     Small Craft Advisory from 3 PM this afternoon to 9 PM PDT
     Saturday 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