041
FXUS66 KEKA 110722
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1222 AM PDT Tue Aug 11 2026

.KEY MESSAGES...

* Slightly cooler, but still hot, interior temperatures are forecast
  through Wednesday.

* Smokey conditions likely from the MP 18 Fire in the Trinity River
  Valley.

* Slight chance of interior thunderstorms late this week or over
  the weekend.

* Minor coastal flooding is possible around Humboldt Bay at the
  evening high tide tonight and Wednesday night.


&&

.SYNOPSIS...Slightly above normal temperatures in the interior
are expected through Wednesday. Coastal areas continue to have
near normal temperatures with overnight stratus clearing in the
afternoons along with breezy northwest winds. There is a slight
chance for dry thunderstorms in the interior late this week.

&&

.DISCUSSION...Smoke from the MP 18 fire continues to impact air
quality over Northern California, particularly in the interior
valleys of Humboldt and Trinity counties. Depending on fire
containment, expect a similar pattern to carry through the week.

The high pressure ridge responsible for the extended period of hot
temperatures is finally beginning to weaken. Temperatures will trend
cooler as a result, but will still be hot through Wednesday. The
heat has greatly dried out the region and fire weather concerns will
be elevated with any increase in winds. See the fire weather section
below.

There will be a more noticeable drop in interior temperatures
Thursday as a troughing pattern settles over the region. High
temperatures in the interior valleys will struggle to break 90 by
Friday, and will continue to lower through the weekend. Clusters
show a potential brief rebound in the ridge late in the weekend
before a deeper area of low pressure potentially develops.

There is some potential for thunderstorm formation under this
troughing pattern, including from various shortwave disturbances
that pass through. Models are showing an uptick in moisture moving
in Wednesday, however instability is meager. This could result in
a few virga showers in the higher terrain, but lightning risk
seems very low. Thunderstorm risk rises slightly (to 5 to 10%)
during the afternoons Thursday through Saturday, with the highest
chances on Friday afternoon. Most activity, if any, seems
regulated to Trinity County, Siskiyou County, and the Yolla
Bollys. This pattern will continue to be closely monitored for
deviations in modeled trends.


&&

.AVIATION...(06Z TAFs)...Stratus has formed around Humboldt Bay
late Monday evening bringing IFR ceilings. LIFR to IFR ceilings
are likely at ACV early this morning with visibility reductions
possible near sunrise. CEC may see stratus, as well, with gusty
south winds advecting stratus northward. Interior areas are likely
to remain VFR outside the river valleys of Trinity and interior
Humboldt County where smoke can lead to visibility reductions.
Stratus is likely to lift late morning into the afternoon. Gusty
north winds are possible again at the coast this afternoon. JB


&&

.MARINE...Strong northerly winds continue in the outer waters.
The largest fetch area being in the Northern outer waters with
gusts over 40 kts in localized areas. South of Cape Mendocino,
the wind field will be wide as it fans out into the southern outer
waters with gusts up to 40 kts or so. Wind wave action from the
northerlies will give 10-12ft wave heights and periods in as many
seconds, creating steep and dangerous sea conditions. The Gale
Warning for the northern and southern outer waters is extended
through Thursday. In addition to the Gale Warning there is also a
small craft advisory (SC.Y) for the inner coastal waters for
steep seas. Otherwise, a long period southerly swell of around 1
ft wave height is due to arrive overnight into early morning
Tuesday. Conditions improve late this week into next weekend. /EYS


&&

.FIRE WEATHER...Elevated fire weather conditions continue within
the mountains of Del Norte and in the King Range as overnight
relative humidity recoveries remain poor to moderate and winds
remain gusty. In Del Norte, easterly winds gusts of up to 30 mph
are possible overnight through Wednesday night. Similarly in the
King Range there will be gusty afternoon northerly winds with
poorer overnight recoveries in the higher elevations. Relative
humidities will trend upwards over the coming days which will
mitigate fire risk.

Minimum RH and overnight recoveries will improve today, especially
in Humboldt, Del Norte, and much of Mendocino Counties, with
moistening westerly flow and lower daytime highs from the
breakdown of the ridge of high pressure. A troughing pattern then
takes shape, which will maintain good recoveries and also
increases chances for a deepened marine layer to infiltrate
farther into the interior.

Monsoonal moisture moves into northern California Wednesday which
may support a few virga showers to develop. There is a low chance
(5-10%) for thunderstorms each afternoon from Thursday through
Saturday, with the best chances on Friday with Trinity and
Siskiyou Counties would be the most likely to see activity. With
cloud bases modeled to be 20k ft or higher, little to no
precipitation is expected to reach the ground. This will continue
to be watched over the coming days.

&&

.COASTAL FLOODING...Sea levels continue to run approximately
0.7 to 0.8 ft above the predicted tide level in Humboldt Bay.
Tides will become more amplified early this week following the
lunar cycle. The predicted tide at the North Spit tide gauge is
7.99 ft MLLW at 11:17 pm on tonight. If the tide continues to run
at around 0.8 ft above predicted, this could result in minor
coastal flooding around Humboldt Bay with minor impacts in King
Salmon and possibly a few other locations around the bay. Additional
minor coastal flooding will be possible for the 12:10 AM high
tide early Thursday morning, although astronomical tides are only
7.84 so the the anomaly would need to increase to nearly a foot.
This is possible as northerly winds will be diminishing and may
locally become southerly. Still any flooding will be very minor if
it occurs.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Coastal Flood Advisory until 1 AM PDT Tuesday for CAZ103.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Coastal Flood Advisory until 1 AM PDT Tuesday for PZZ415.

     Small Craft Advisory until 9 AM PDT Thursday for PZZ450.

     Small Craft Advisory until 3 AM PDT Wednesday for PZZ455.

     Gale Warning until 9 AM PDT Thursday 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.

Visit us at https://www.weather.gov/eureka

Follow us on Facebook and Twitter at:
https://www.facebook.com/NWSEureka
https://www.twitter.com/NWSEureka

For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png