614
FXUS66 KEKA 240620
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1120 PM PDT Mon Jun 23 2025

.SYNOPSIS...Near to slightly above normal temperatures expected into
late week. Breezier winds possible mid to late week, bringing
elevated fire weather concerns. Much warmer temperatures possible
over the weekend.


&&

.DISCUSSION...Mid to high cloud cover will continue to move over the
region overnight beneath a weak upper shortwave. A shallow marine
layer persists along the north coast, producing areas of patchy fog
in along the coasts of Humboldt and Del Norte.

Warm and dry conditions will continue through Wednesday as a broad
ridge builds in from the eastern Pacific. Temperatures in the mid to
upper 80`s with isolated valleys reaching the low 90`s expected (NBM
70 to 80%) including Lakeport, Ukiah, Covelo, Redway, Weaverville,
Hayfork and Willow Creek. Temperatures along the coast especially
north of Cape Mendocino will be much cooler beneath a persistent
marine layer. Daytime winds will be broadly NNW and terrain driven
around higher elevations. Daytime RH values forecast 15 to 25%,
especially across Lake and interior Mendocino and Trinity counties.
Although winds are not expected to be especially strong, high
temperatures and low daytime humidity will pose fire weather concerns
for these areas.

Models are still in general agreement on broad upper level troughing
initiating a few weak shortwaves late Wednesday through Friday.
Breezy northwesterly winds each afternoon will prolong fire weather
concerns for Trinity, Mendocino and Lake counties. Current NBM
probabilities around 50 to 60% for gusts exceeding 25 mph, including
coastal areas. Additionally, temperatures look to rebound into the
triple digits heading into next weekend as long range models show
persistent ridging over the PNW NBM 30 to 50%). As mentioned in the
previous discussion, the influence of the upper-level low off the
coast along with the heat could possibly bring dry thunderstorms.
Confidence is low as the position of the upper-level low is
uncertain and will determine how much moisture is available for
convection.


&&

.AVIATION...06Z TAF: Through Tuesday morning, the forecast signal
is complicated by the passing of a compact shortwave trough. High
resolution soundings point to a deepening marine layer and higher
CIGS from this feature. Outside of this quick passing disturbance,
the environmental setup is otherwise primed for shallow CIGS and
fog. Current thinking is that the shortwave will have a disruptive
influence on mainly visibility, but also ceiling heights. Confidence
is high for LIFR levels and visibility has a chance to enter fog
levels, especially into early Tuesday morning. Inland terminals,
including UKI will remain VFR with light surface winds.


Forecast Confidence:

Chance for LIFR CIGS High: Coastal Terminals have 60-80%, but
variability is possible.

Fog probability Low to Moderate: Coastal Terminals 30-40% and
variability is expected.



&&

.MARINE...Northerly winds will remain stronger in the southern
zones, especially around the Cape. Strong breezes around 25 to 30kts
should be expected in the focused expansion fan south of the cape
this week. Light to moderate breezes up to 15 kts will remain in the
northern waters for most of the week. The northerlies will trend
strong late in the week and likely through the weekend. Other than
short period northerly seas, minor mid period northwesterly swells
will enter the waters this week.


&&

.FIRE WEATHER...Warm and dry conditions are expected this week into the
weekend. Afternoon RH remain low, into the teens or 20s for much of
the interior. Overnight recoveries remain good in the valleys and
moderate to good in the higher terrain. Afternoon northwesterly
breezes could gust up to 15-20 mph in the valleys with slightly
higher gusts possible in the higher terrain of southern Mendocino
and Lake Counties. Slightly stronger northwesterly winds are
possible Wednesday to Friday, with gusts up to 25 mph possible in
the valleys and gusts to 30-35 mph possible in the highest terrain.
Late this week into the weekend, a ridge starts to build while an
upper-level low looks likely to form off the coast. Higher
temperatures are forecast with triple digits possible in the
valleys. If the upper-level low off the coast is positioned in a way
to bring enough moisture into the area, convection is not out of the
question with any thunderstorms likely to be dry. Confidence is low
(less than 5%) at this time. JB


&&

.TIDES/COASTAL FLOODING...The lunar cycle will go to a new moon on
Wednesday. This will create large tidal swings and possible some
minor coastal flooding around Humboldt Bay this week. Evening to
late night high tides this week will exceed 8 ft. Though levels may
falls short of advisory levels (8.8 ft), high tides plus a minor
positive anomaly will likely push tides to around 8.5 feet. Large
overnight to early morning tidal swings to -2 feet will also create
fast currents in channeled waterways.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 11 PM PDT Wednesday 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