Arcata, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

372
FXUS66 KEKA 212246
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
246 PM PST Fri Feb 21 2025

.SYNOPSIS...Upper and mid-level clouds are filling in ahead of
inclement weather with stratus returning to the coast. The chance
for rain increases this weekend and continues into early next
week. Gusty southerly winds expected along the North Coast and
over the interior mountains this weekend and early next week.



&&

.DISCUSSION...Despite a synoptic ridging pattern lasting through the
next several days and into next week, a series of disturbances will
incorporate subtropical moisture and inundate the area mostly to the
north our CWA. More immediately, 500mb heights show the ridge
flattening a bit Saturday, which will allow some of this
precipitable water to train over Del Norte and Humboldt counties.
Tonight there looks to be an initial phase of this series of pulses
but the probabilities are negligible to none according to high res
models yet CAMs show light showers tonight if any. This first slug
of moisture will produce light precip locally as the majority of
accumulation will be north of 43N, which will hit Oregon and
Washington early Saturday morning with an IVT magnitude of around
750kg/m/s. The next frontal boundary will produce beneficial rain by
the late afternoon into the early evening on Saturday. Expect mostly
beneficial rainfall. Minor nuisance flooding is possible with the
heavier rainfall Saturday night into early Sunday. Mudslides will
also be possible in the steep terrain on highway 199 in Del Norte
County Saturday night when the heaviest rain rates occur.

Otherwise, expect mild temperatures with a chance for light rain for
the remainder of the area during the weekend. Gusty winds will also
occur with this stationary boundary and minor impacts are possible
especially over the coastal headlands. A surface low is forecast to
develop just outside 135W north of 40N on Monday and stronger wind
gusts to 50 mph are possible for the coastal headlands and interior
ridges as the pressure gradient tightens and a 925mb southerly 50kt+
speed max develops along the coast in advance of a frontal boundary.
The exact timing remains uncertain, though the ECMWF has been
clustering around Monday afternoon/evening with ensemble mean gusts
near 50 mph for Pt St George and KCEC airport.
Looking at the NBM, 90th percentile max gusts are on the order of 55
to 65 mph over the interior mountains of Del Norte with lower
probabilities for gusts over 50 mph for the Humboldt interior
mountains; Kneeland and Berry Summit. Wind this strong will make
driving difficult and could knock down tree branches.

Precip should start to end on Tue as broad upper ridging quickly
springs back and holds into mid week (Wed). The ridge aloft with
above normal 500mb heights will likely remain the dominant feature
controlling NW California weather into late next week. Temperatures
will likely remain above normal. /DB /EYS


&&

.AVIATION...High level cloud cover has been increasing this
afternoon across the north coast ahead of an approaching upper
shortwave. VFR conditions have prevailed as a marine stratus deck
has mostly remained offshore, but increasing onshore flow may
produce scattered MVFR ceilings/mist this afternoon, especially at
ACV. This initial shortwave will bring the potential for light
rain showers overnight into early Saturday morning. Model
reflectivity indicates the highest potential for scattered showers
at CEC between 04-08Z, but any accumulation would be minimal
(<.10 in). HREF probabilities are <30% for ceilings <2000 feet
overnight, although brief periods MVFR ceilings are possible with
these passing showers. Southerly winds will steadily increase
Saturday ahead of a stronger frontal boundary. Heavy rainfall and
gusty winds 25 to 35 mph are possible in northern Humboldt and Del
Norte county late Saturday night into Sunday as this front moves
onshore.


&&

.MARINE...A mid-period westerly swell 9-11 feet at 15 seconds
will build into the waters this evening. Light westerly breezes
will turn southerly and increase overnight ahead of an approaching
upper shortwave, elevating the sea state to advisory levels as
significant wave heights surpass 10 feet. Near gale force gusts
are possible in the northern waters late Saturday night into early
Sunday morning as a fast-moving frontal boundary moves onshore.
Responsive 7 to 9 foot wind waves will enhance already elevated
seas through Sunday. An active upper trough pattern will sustain
elevated southerlies through early next week; a stronger front is
possible Monday afternoon with potential for gale force gusts
coinciding with the arrival of a large, long period westerly
swell.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Beach Hazards Statement through late tonight for CAZ101-103-
     104-109.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from 3 AM Saturday to 3 PM PST Sunday
     for PZZ450.

     Small Craft Advisory from 3 AM to 3 PM PST Saturday for
     PZZ455.

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

     Small Craft Advisory from 9 PM this evening to 3 PM PST
     Saturday for PZZ475.

&&

$$

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