104
FXUS66 KEKA 161207
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
507 AM PDT Wed Apr 16 2025

.SYNOPSIS...A weak weather system will bring near normal
temperatures, coastal clouds and a slight chance for afternoon
mountain thunderstorms. Clearing skies and slightly warmer
temperatures are expected Thursday and Friday. Continued seasonal
temperatures and dry weather are expected into next week.

&&

.DISCUSSION...The upper level low off the central CA coast is
continuing to bring moisture and mid level clouds to much of
northern CA. An upper level trough is approaching from the north
and this will help to push the upper level out of the area and
usher in some cooler and drier air. Before this dry air moves in there
is a small window for a few thunderstorms over the interior
mountains again this afternoon. Lapse rates aloft are still steep,
between 7.5 and 8 c/km and the models are showing some
instability. At the coast this afternoon northerly winds are
expected to start picking up again. This, combined with the dry
air aloft is expected to help clear out much of the coastal
stratus north of Cape Mendocino. However farther south is
expected to remain cloudy.

Wednesday night into Thursday morning easterly winds are expected
to develop aloft and this is expected to start clearing out the
coastal clouds with most areas clear by the afternoon. Offshore
flow is expected to return again Friday morning with east winds
of 15 to 25 kt at 925mb and 850mb. This is expected to bring
mostly clear skies to the area. This will also allow temperatures
to drop and will likely be the coolest morning of the week in the
calm valleys. Some frost is possible in the coldest valleys of
Trinity county.

Friday night into Saturday the offshore flow decreases and this
may allow some fog or stratus to form again in the coastal areas.
A weak front is expected to move across the area on Saturday
bringing cooler temperatures to mainly Humboldt and Del Norte
counties. All of the ensemble clusters are showing the rain
remaining north of the area. Sunday and into early next week the
flow remains northwest or westerly with occasional weather
systems moving through the flow and bringing an increase in clouds
and slightly cooler temperatures. There is good agreement that the
weather will be dry through the period. Temperatures are expected
to be near to slightly above normal with upper 50s at the coast to
upper 60s in the warmer interior valleys. MKK

&&

.AVIATION...IFR ceilings prevail at the coastal terminals early this
morning, with a deeper marine layer along the coast. The
McKinleyville profiler indicates a marine layer depth up to around
2,500 feet MSL. Patchy drizzle has been occurring along the North
Coast as result of this uniform saturated layer. Otherwise, stratus
are expected to gradually lift and scatter out during the morning
and early afternoon as an approaching cold front destabilize the
marine layer. After 16Z, VFR conditions with clearing skies are
expected at CEC as northerly winds increase nearshore. Winds will
become N at 5-10 kt at 16Z, increasing after 18Z to around 15-25kt
with gusts from 25-35kts...with the strongest winds from 16/21Z-
17/03Z. Northerlies ease after 17/03Z, but will remain breezy into
Thursday.

For ACV, conditions are expected to improve to VFR after 19Z as low
clouds scatter out. HREF model indicate MVFR to IFR conditions
redeveloping in the vicinity of Humboldt Bay after 17/02Z, with a
70% chance of ceilings below of 2kft at ACV at 17/05Z. Winds will
remain very light and variable through 18Z, becoming WNW from 5-15
kts after 20Z with occasional gusts.

Meanwhile, MVFR ceilings and calm winds will persist at UKI through
late morning. After 18Z, low clouds are expected to lift and scatter
out to aid in VFR conditions. Winds will peak from SE around 5-10
kts with occasional gusts after 19Z, becoming variable after 2Z.
HREF indicates the marine layer deepening along the Mendocino
Coast after 00Z, with a probability of ceilings lower than 2kft at
UKI about 20-40% around 17/02Z increasing to 70% after 17/05Z.

&&

.MARINE...Gale force northerlies and very steep northerly waves are
forecast to increase through early evening over the northern outer
waters after the passage of a relatively dry cold front.
Chance for gale force northerlies (35-40kt) is forecast to expand
into portions of the northern inner waters this afternoon and
evening, primarily near and downwind of Pt St George. A few gusts to
50 kt are possible (20% chance) as a thermal trough takes shape
nearshore. Very steep northerly waves are forecast to build over the
northern outer waters tonight, and peak around 15 kt this afternoon
and evening. These steep waves will spread into the southern waters
outer waters and northern inners this afternoon and evening, and
probably persist into the overnight hours. Hazardous Sea Warning
remain in effect for the northern inner waters and southern outer
water. Very steep waves will likely persist on Thu before winds and
seas trend downward by Friday. Northerlies and very steep waves will
most likely ramp up again over the weekend after passage of another
dry cold front. DB

&&

.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 from 3 PM this afternoon to 3 AM PDT
     Thursday for PZZ475.

&&

$$

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