Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 231139
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
439 AM PDT Sat Mar 23 2024

.SYNOPSIS...A round of showers is moving across the area
currently with another round of showers and isolated thunderstorms
expected late this morning and afternoon. Snow levels will be
around 3500 to 4000 feet. Showers will slowly diminish Saturday
night Sunday. Mainly dry weather is expected Sunday afternoon
through Tuesday. Another round of wind and rain is expected mid to
late in the week.

&&

.DISCUSSION...The upper level low remains off the coast with
multiple shortwaves rotating around it this morning. Numerous
showers are moving onshore this morning. Snow levels look to be
around 3500 to 4000 feet in most areas. This morning there will
likely be some breaks in the showers. This afternoon another
shortwave is expected to combine with the heating of the day
bringing increased instability. The NBM mean shows 100 to 200
j/kg of CAPE across the area peaking late in the afternoon. This
will bring the potential for more widespread showers and a few
thunderstorms. Small hail is possible in the stronger showers, but
with freezing levels close to 4,000 feet it is not expected to
accumulate significantly on roadways. Tonight showers will start
to diminish in coverage, especially in Mendocino and Lake
counties. Rainfall totals for today and tonight are expected to
be 1 to 2 inches in Humboldt and Del Norte counties with 0.25 to
1.5 inches in Trinity, Mendocino and Lake counties. These will
likely vary quite a bit due to the convective nature of the precip
today. Models have slowed down the upper level low exiting the
region and showers may linger into Sunday morning more than
previously expected. Amounts Sunday morning should be relatively
light, less than a quarter inch in most areas. Snow levels will
also be the lowest, dropping to around 3,000 feet to 3,500 feet.

Sunday night there will be a brief break in the rain, although
quite a few clouds will linger. Any valleys that do manage to
clear out briefly will likely see fog return overnight. Monday a
weak warm front is expected to bring some clouds and possible
light rain mainly in the afternoon. Tuesday another wave moving
over the top of the ridge is expected to bring more clouds and
some light rain or drizzle. Any rain that does fall is expected to
be less than a quarter of an inch.

Tuesday night or Wednesday another area of upper level low
pressure starts to approach the area. This will bring the
potential for moderate to heavy rain, strong winds and mountain
snow. The NBM shows widespread probabilities of over 50 percent
that we will see wind gusts above 45 mph in the mountains. The NBM
is showing probabilities of greater than 50 percent we will see 2
inches of rain on Wednesday and Thursday across much of the
higher terrain of Del Norte, Humboldt and Trinity counties. These
probabilities rapidly decrease as you move south into Mendocino
county and Lake counties. Friday colder air is expected to move
into the area and snow levels drop. NBM is showing a 40 to 60
percent chance of over 4 inches above 4,000 feet in Trinity
county. MKK

&&

.AVIATION...Showers will impacts the coastal terminals throughout
the TAF period with MVFR conditions at ACV and CEC for much of
the day. IFR will be possible during the heaviest showers and
possible thunderstorms. No lightning has yet been observed off the
coast near the approaching low pressure system, but afternoon
instability may be just enough to see some thunder at coastal
sites as the main band of showers moves through the region this
afternoon/evening. Farther inland thunder is less likely but still
not impossible. Southerly winds will decrease markedly this
afternoon and gradually turn westerly then northwesterly
overnight. /RPA

&&

.MARINE...An area of low pressure will move into southern Oregon today
gradually bringing an end to the strong southerly winds that have
been impacting the coastal waters overnight and into this morning.
These winds have also brought steep seas to the coastal waters which
have now combined with a building westerly swell. Seas have reached
low end hazardous seas criteria at this hour and may continue to
bounce up and down out of criteria through midday. Considering
policy requires dropping the small craft completely to upgrade a
hazardous seas warning, and thus losing the highlight of the
elevated seas into Sunday, we have opted to not issue a hazardous
seas warning at this time and instead stick with a high end small
craft. Winds will turn out of the west and then northwest this
afternoon into Sunday while the swell continue to move through the
waters. Small crafts have been extended through Sunday to cover the
continued elevated seas and northwest gusts over 25 kt.

Seas will subside Monday into Tuesday as winds become lighter under
a passing upper level ridge. Southerly winds will ramp up again
Tuesday night into Wednesday ahead of the next approaching front
with high probabilities of small craft conditions and possible
gales. Once again a trailing westerly swell is also expected with
seas potentially building to over 15 feet into Thursday. /RPA

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Winter Weather Advisory until 11 PM PDT this evening for
     CAZ107.

     Winter Weather Advisory until 11 AM PDT this morning for
     CAZ108.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 6 PM PDT this evening for PZZ450.

     Small Craft Advisory until 3 PM PDT Sunday for
     PZZ455-470-475.

&&

$$

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