588
FXUS66 KEKA 250843
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
143 AM PDT Wed Jun 25 2025

.SYNOPSIS...Breezier winds possible today through Friday, bringing
elevated fire weather concerns. Seasonable temperatures are
expected to continue today through Friday, followed by hotter
weather this weekend and into early next week. Moderate to locally
major HeatRisk this weekend, especially on Sunday.


&&

.DISCUSSION...GOES-West satellite imagery depicts a deepening marine
layer and stratus blanketing the coastal waters, and extended up the
adjacent river valleys. The McKinleyville profiler indicates a
marine layer depth up to around 2500 feet MSL. Patchy drizzle has
been occurring along the North Coast as a result of this saturated
layer. Otherwise, stratus are expected to gradually lift and mix
out during the afternoon hours as an approaching shortwave
destabilize the marine layer. Interior high temperatures are
forecast to remain at or near-normal, with highs in the mid 80`s
to low 90`s across the valleys and 70`s in the mountains. While
highs for the coastal areas in the upper 50`s to low 60`s.

Breezier west-northwesterly winds are likely through the channeled
terrain today through Friday. NBM is showing around 65-85%
probabilities for gusts over 25 mph in the valleys of Trinity,
Lake, and interior Mendocino. Higher gusts are possible over the
surrounding ridges. While these winds are not too unusual,
combining these with warm temperatures and low afternoon humidity
could bring localize elevated fire concern. Coastal headlands
have similarly high wind probabilities, especially in Cape
Mendocino and Pt Arena.

The offshore ridges will moves over the area this weekend and
into early next week, and a warm deep-layer air-mass will develop
across the WRN- CONUS. Meanwhile, a reversal upper-level trough
forming off the coast of California. Model guidance has been very
consistent supporting 850 mb temperatures of 25-30C or so over the
eastern portion of the forecast area, including interior
Mendocino, Lake and Trinity counties. Interior heat will build on
Friday and then peak on Sunday. NBM is showing 40-80%
probabilities for the hottest valleys to see triple digits by
Saturday and 50-100% probabilities by Sunday, with the highest
chance in the Trinity County. The heat risk is forecast to be
minor to moderate over the area, but a locally major heat risk is
expected to occur over portions of Trinity County on Sunday. The
heat will have impacts on some individuals sensitive to heat,
especially those without effective cooling and/or adequate
hydration. At this point, those major heatrisk are expected over
isolated areas. However, we are going to continue monitoring in
case a heat product is needed. Even the coastal areas are expected to
warm up into the 70`s before the seas breezes developed.


The influence of the upper- level low off the coast along with
the heat could possibly bring the potential for some 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. ZVS/JB



&&

.AVIATION...(06z  TAF)...A weak, shallow marine layer has gradually
blanketed the coast through evening. MVFR ceilings have mostly
filled in by midnight though some coastal areas continue to see
short periods of scattering. Ceilings are expected to lower through
he night with consistent IFR and even LIFR (60% chance) ceilings and
visibilities around sunrise. Most models indicate better scattering
along the coast compared to the past few days with an 80% chance of
VFR conditions by early in the afternoon. Similarly, most models
show a marine layer slower to reform Wednesday night though about 80%
still have at least MVFR ceilings fill in by midnight. /JHW


&&

.MARINE...Fresh to strong northerly breezes have persisted in the
southern waters overnight with gusts observed up to 25 kts. Winds
will push into the southern inner waters during the day Wednesday as
a shortwave crosses the area. The northern waters will remain much
more calm with gust struggling to reach above 20 kts. Northerlies
will generally intensify and spread further north late in the week
with near gale force gusts fanning south of Cape Mendocino through
the weekend. Aside from a very minor northwest mid period swell,
seas will be dominated by short period seas as steep as 7 feet at 6
seconds. /JHW


&&

.FIRE WEATHER...Warm and dry conditions are expected this week
into the weekend. Overnight RH`s recoveries continue good across
the valleys and moderate in the higher terrain. Afternoon RH
remain low, into the teens or 20s for much of the interior.
Breezier west- northwest winds are likely today through Friday,
with gusts from 20 to 30 mph possible through the channeled
terrain and gusts to 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 10%) at this time. JB


&&

.COASTAL FLOODING...The lunar cycle will go to a new moon on
Wednesday. This will continue to create large tidal swings and
some minor coastal flooding around Humboldt Bay this week. Evening
to late night high tides this week will exceed 8 ft. Water levels
may reach advisory level (8.8 ft) with the addition of a minor
positive anomaly. Large overnight to early morning tidal swings to
-2 feet will also create fast currents in channeled waterways. A
 Coastal Flood Advisory is out until 1 AM Wednesday.



&&

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

NORTHWEST CALIFORNIA COASTAL WATERS...
     Coastal Flood Advisory until 1 AM PDT early this morning
     for PZZ415.

     Small Craft Advisory from 11 AM this morning to 3 PM PDT
     Thursday for PZZ455.

     Small Craft Advisory until 3 PM PDT Thursday 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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https://www.weather.gov/images/eka/zonemap.png