173
FXUS66 KEKA 162155
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
255 PM PDT Wed Apr 16 2025

.SYNOPSIS...Coastal clouds, seasonal temperatures and mostly dry
weather expected into early next week.

&&

.DISCUSSION...An upper level low off the central CA coast is continuing
to bring mid level moisture in wrap around flow to the eastern
and southern portions of the forecast area today. An upper level
trough is approaching from the north and this will push the cut-
off low out of the area tonight, ushering in drier northerly air.
Before this dry air moves in there is a small window for isolated
and very weak thunderstorms over the interior mountains this
afternoon, particularly in SE Trinity, NE Mendocino and NRN Lake
counties. Main hazard from this high based convection will be
isolated cloud-to-ground strikes and perhaps gusty outflow winds.

Low cloud cover has cleared out along the Del Norte County today
in response to much stronger northerlies and drier air mixing
down to the surface. Northerly winds have been gusting to 37 mph
at Crescent City ASOS and should hit 40-45 mph by 6pm per HREF
(an 80% chance). The strong winds were very localized with winds
at Crescent harbor gusting only to 25 mph.

Stratus has persisted longer into the afternoon hours over the
Humboldt Bay area and Eel delta, but has been slowly eroding and
should clear out by late afternoon. BUFKIT boundary layer humidity
profiles are favorable for stratus redevelopment this evening and
overnight around Humboldt Bay area and Eel delta. In fact,
visible satellite imagery already showed new slivers of stratus
forming offshore this afternoon. Meanwhile, a small scale eddy in
the lee of Cape Mendocino will most likely keep stratus locked-in
tonight into Thur along the Mendo coast. Deep marine layer
conditions and low cloud cover will probably push into the
southern interior of Mendocino County again (Ukiah area) tonight.

Chance for longer lasting clearing is expected to increase Thu and
Fri as northerly and northeast flow continues over the area. There
is considerable uncertainty with amount of clearing along the Mendocino
coast and stratus intrusion via the Russian river valley in southern
Mendocino county. Models have not been resolving small scale circulations
very well. With the passage of an upper trough tonight and ridge
building aloft, extensive cloud cover should diminish on Thu.

A weak front is expected to move across the area on Saturday and
may generate another deep push of low clouds and perhaps a few spats
of North Coast drizzle. Otherwise, seasonal temperatures and low
chances for measurable precip are expected. There is considerable
variability in possible outcomes with a series of transient shortwave
troughs early to mid next week. These troughs could create a favorable
environment for interior showers sparking up with daytime heating
or may even generate some rain. Greater uncertainty arises mid to
late week with potential for an even colder and wetter scenario.
So far there isn`t a clear signal from the NBM on this yet. DB

&&

.AVIATION...A deep marine layer finally scattered out most of the
north coast this afternoon as northerly winds increase, while ACV is
still holding on to a patch of overcast MVFR ceilings. Gusts
exceeding 30 knots are likely at CEC through late afternoon, while
ACV will be more shielded with 10 to 15 knot gusts - brief MVFR
scattering is likely before 00Z as well. The marine layer will
remain destabilized by a dry cold front descending into NorCal this
evening, but will likely rebound after 03Z for ACV and UKI as
northerly winds diminish. HREF has a 50 to 60% probability for
ceilings <1000ft persisting through late Thursday morning. Offshore
breezes will likely keep most coastal stratus at bay for CEC.

&&

.MARINE...Gale force northerly winds and steep wind waves continue in
the outer and northern waters this afternoon. Gusts exceeding 35 to
40 knots are expected through this evening, including near Point St.
George, before winds begin to diminish overnight. Conditions in the
inner waters will quickly fall below advisory levels while seas in
the outer waters will remain steep and hazardous through Thursday
afternoon. Fresh to strong breezes will likely persist in the northern
outer waters through Friday before widespread strong northerlies
return this weekend. NBM has 50 to 75% chance for gale gusts approaching
40 knots developing by Saturday evening in the outer waters, although
uncertainty increases early next week for longevity of these
gales, especially in the southern waters.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 4 PM PDT this afternoon for
     PZZ450.

     Hazardous Seas Warning from 4 PM this afternoon to 3 AM PDT
     Thursday for PZZ450.

     Gale Warning until 3 AM PDT Thursday for PZZ470.

     Small Craft Advisory until 3 PM PDT this afternoon for
     PZZ475.

     Hazardous Seas Warning until 3 AM PDT Thursday for PZZ475.

&&

$$

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