Small Craft Advisory 17, NWS Eureka, CA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
235 PM PST Thu Feb 8 2024

.SYNOPSIS...Cooler conditions are expected tonight and Friday. A
couple of weak systems will bring a chance for light precipitation
Friday and again on Sunday, otherwise dry weather is expected.
Potential for more impactful precipitation is forecast for late
next week into next weekend.

&&

.DISCUSSION...Light or low impact precipitation is forecast for
Friday as a weak system drops down from the northwest. Upper
level ridging over the eastern Pacific has been building closer
to the coast this afternoon with cool, dry and stable conditions
prevailing across the forecast area today. High resolution
models, namely the HRRR and ARW indicate low potential for a few
light showers into early this evening, however. This is most
likely overdone with drier north-northwesterly low level flow and
warming temperatures aloft and increasing stability.

High resolution mesoscale model guidance indicates light and low
impact precipitation returning on Friday as weak trough in N-NW
flow moves southward across Del Norte and northern Humboldt.
HREF means indicate generally under 0.15in/6hr for Del Norte and few
hundredth or less for Humboldt. NAM-nest is much wetter while the
FV3 is completely dry. Global models on the other hand, namely the
GFS and ECMWF, are almost completely dry. NBM precip probs are
usually too low in these low QPF situations. Moist N-NW low level
flow is forecast to re-develop by Friday evening and additional
light or low impact precipitation is expected into the evening
hours.

Dry and stable weather is forecast to return on Saturday as the
offshore 500mb ridge progresses across the forecast area. Expect
considerable valley low clouds and fog in the morning on Sat.
Another weak shortwave trough is forecast to move over the ridge
by Sunday. Precipitation chances for a few hundredths are only
10-20% for Del Norte and northern Humboldt. Otherwise, dry
weather with higher daytime temperatures and chilly morning lows
are expected for much of the forecast area through this weekend.

Ensemble means indicate broad flat ridging with above normal 500mb
heights dominating early to mid next week. This will most likely
result in predominately dry and stable weather for NW California.
Weak shortwaves may move over the top of the ridge and provide
light (non-impactful) amounts of precip. Probabilities for an
inch or more of rain in 24 hours increases (20-30%) late next
week and next weekend as progressively stronger frontal systems
move into the dominant ridge. There are very large spreads in
precip and high uncertainty with timing. A good example of the
spread is Honeydew, a climatologically favorable location for
heavy rain. The 25th-75th percentile spread over a 24 hour period
ending 4 AM Sat is 0.0 to 2.96 inches. Probabilities for 2, 3 and
4 inches in 24 hour increase over the weekend, but once again with
large 24 hour spreads and huge timing differences. Stay tuned. DB

&&

.AVIATION...The most challenging part of the forecast will be any
lowered visibility due to moist low-levels and light or calm winds
developing, especially over KUKI. Kept the coastal terminals VFR,
but did go with a short-term IFR visibility for KUKI for late
tonight/early Friday morning as forecast soundings would support
this, although model ensembles are not picking up on this potential
feature. VFR conditions other than this as upper level ridging
builds in. Some increase to wind speeds from the north this
afternoon and early evening is anticipated, but not all that
significant. Some cloudiness is forecast to move in Friday, mostly
in the 4-6KT foot ceiling range, keeping us VFR. MH

&&

.MARINE...Fresh to strong northerly breezes over the waters
today are expected to gradually ease tonight into Friday as the
pressure gradient loosens. Seas will remain steep and elevated
across the waters today into tonight as a decaying long to mid
period westerly swell combines with a shorter period northwesterly
waves. Significant wave heights around 10-13 feet are forecast
into this evening with dominate periods fluctuating from 11 to 17
seconds. The Hazardous Seas Warning for the southern outer waters
has been extended into this evening for short period waves up to
10 ft. A longer period westerly swell will build tonight and
maintain combined seas around 10 feet through early Friday
morning. Another long period westerly will build on Saturday and
may pose a risk to beachgoers due to increased wave run up on the
beaches. Depending on the short period wave components, a beach
hazard statement may need to issued. Beyond Sat, a calmer wind
regime with split flow across the waters is forecast. Light
southerlies will eventually unfold throughout with seas trending
down by early next week. ZVS/DB

&&

.BEACH HAZARDS..Higher than normal tides is forecast to continue
today and this weekend, with the high tides expected to peak on
Friday. For today, high tides are forecast to be at 8.1 feet at the
North Spit tide gauge at around 9:18 AM. Northerly winds will lessen
the height of surge, but both surge and tidal anomalies will still
combine with the high tide at the North Spit with water levels
between 8.9 and 9.0 feet by 9:48 AM. Minor coastal flooding around
King Salmon and Jackson Ranch Road in the Arcata Bottoms will be
likely between 8AM and noon. A Coastal Flooding Advisory will be in
effect from 8AM through 12PM Today.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 AM PST Friday for PZZ450.

     Small Craft Advisory until 9 AM PST Friday for PZZ455.

     Small Craft Advisory until 3 PM PST Friday for PZZ470.

     Hazardous Seas Warning until 9 PM PST this evening for
     PZZ475.

&&

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