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000
FXUS66 KEKA 201140
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
440 AM PDT Sat Apr 20 2024

.SYNOPSIS...A weak cold front will bring few light showers and
drizzle to the North Coast this afternoon, followed by breezy
northerly winds on Sunday. Generally dry weather will continue
through early next week.


&&

.DISCUSSION...Stratus and patchy fog has expanded and blanketed
much of the coastal waters and adjacent land areas this morning,
especially south of Cape Mendocino. However, stratus should clear
out quickly with a weak low level inversion. Water vapor
satellite shows a weak cold front approaching the West Coast. This
features is spreading high clouds across the area. Models
continue to show very little to no precipitation from this front.
Have slightly lowered the pops for today, but some light rain and
drizzle still expected to Del Norte and northern Humboldt counties
during the afternoon or early evening. Otherwise, dry weather is
expected to continue with some cooling of interior high temps.
Breezy west to northwest winds will developed across the inferior
after frontal passage late in the day and evening, especially in
channeled terrain and ridges where gusts to 30 mph are probable
(75%-90% chance per HREF) for Lake and far southern Mendocino
counties.

Surface high pressure will build in quickly over the region late
tonight and into early next week. Interior temperatures are
forecast to rebound Sun through Tue as a flat ridge aloft springs
back up and offshore flow returns. Breezy northerly winds are
forecast to redeveloped over mostly coastal areas as surface
pressure gradients tighten by early Sunday. Gusts of 25 to 35 mph
are likely in many exposed locations; locally higher over the
coastal headland and ridgetops Sunday afternoon. HREF has over a
80% probability for gusts > 40 mph over the King Range and 50-70%
probability for coastal SW Humboldt by 5 AM Sunday, and 70%
probability for Crescent City by 2PM Sunday. Interior temperatures
are forecast to rebound Sun through Tue as a flat ridge aloft
springs back up and offshore flow returns.

Tuesday, ensembles and deterministic models are showing a cutoff
low dragging southward just off the California Coast. This will
bring a onshore flow promoting a cool down across the interior to
near seasonably temperatures. Isolated showers or thunderstorms
are possible (20%-30% chance) over the higher terrain of Trinity
County Tuesday afternoon and evening as a 500mb shortwave trough
progresses eastward toward the PAC NW.

Potential for wider coverage and more frequent precipitation will
increase mid to late next week, though probabilities for > 0.50 inch
of rain in 24-hours for the western slopes of Del Norte and northern
Humboldt Counties are about 20% or less. Afternoon high temperatures
are forecast to cool down with probabilities for 75F or more no more
than 30% for the warmest interior valleys of Mendocino and Lake. NBM
means are close to normal (high in the 60`s). Thus, it is shaping
up to be cooler compared to the recent interior warmth. How fast
it cools down and to what degree are still uncertain. Precipitation
may occur and based on the ensemble guidance, amounts are most likely
going to be light. Even light amounts may have minor impacts on
outdoor plans, but timing and duration of rain or showers remain
elusive and uncertain at this time. Stay tuned.


&&

.AVIATION...(12z TAFS) A very thin layer of coastal stratus is
visible on satellite this morning lurking along the coast, but it
has so far only inconsistently been able to move on shore due to
disruptions from passing high level clouds. Conditions for coastal
terminals will continue to oscillate between VFR and LIFR conditions
early this morning as the line of stratus dances along shore. Though
models suggest good chances of quick clearing skies later this
morning (NBM shows only a 10% chance of IFR conditions past 8 AM),
gentle wind turning onshore suggest this probability is a little
underdone. Still, northwest wind will continue to build through the
evening along the passage of a weak cold front. This cold front
itself will likely bring some very weak showers and brief MVFR
conditions, but it will also more widely mix out any low stratus
headed through Saturday night, greatly reducing the chances of any
IFR conditions. Otherwise, VFR conditions are expected across the
interior. /JHW


&&

.MARINE...Currently weak southerly wind and an unusually calm sea
state will quickly shift this afternoon behind a weak surface cold
front. Northwesterly wind will build through the waters from north
to south with gusts over 21 kts in the outer waters later this
evening. Wind will continue to increase with gale force gusts
throughout the outer waters during the day on Sunday. Winds will
remains lightly calmer closer to shore, though gale force gusts
should still be expected right along shore around Cape Mendocino and
Pt. St. George. Strong winds will build steep short period seas in
excess of 10 feet by Sunday afternoon.

Weak high pressure building over California will help gradually
shunt the strongest wind offshore starting Monday, which will allow
at least nearshore conditions to gradually calm early this week.
Wind waves will dominate the sea state through early week with a mid
period swell up to 5 feet building Sunday being to only other
notable feature. /JHW


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from midnight tonight to 9 PM PDT
     Sunday for PZZ450.

     Small Craft Advisory from 3 AM to 9 PM PDT Sunday for
     PZZ455.

     Small Craft Advisory from 9 PM this evening to 3 PM PDT
     Sunday for PZZ470.

     Gale Warning from 3 PM Sunday to 3 AM PDT Monday for PZZ470.

     Small Craft Advisory from 6 PM this evening to 3 AM PDT
     Sunday for PZZ475.

     Gale Warning from 3 AM to 9 PM PDT Sunday for PZZ475.

&&

$$

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