202
FXUS66 KEKA 172135
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
235 PM PDT Fri May 17 2024

.SYNOPSIS...Temperatures inland will continue to cool to at or below
seasonal averages through the weekend. Coastal stratus will diminish
this weekend.


&&

.DISCUSSION...Clear skies have finally prevailed across the
entire region this afternoon. Widespread coastal stratus will likely
subside into the weekend as a trough moves through the Pacific
Northwest, weakening the morning inversion. Little additional
moisture arrives with this trough and rain is not expected, though
winds will be stronger this weekend. Saturday, NBM shows a 20-30%
probability of wind gusts greater than 30 mph at coastal Humboldt
and Mendocino and a 60% chance at coastal Del Norte. Sunday, this
increases to 90% across the entire coast along with ridgetops.
Interior Lake and Mendocino counties will be gusty as well with NE
gusts up to 25 mph possible. Slightly stronger offshore winds in
Lake and Trinity counties, especially on the ridgetops, look
possible Monday afternoon, with around a 50% of NE gusts above 30
mph at the ridgetops.

Sunday afternoon and Monday morning are expected to be much colder
than this last week, with temperatures in Humboldt, Del Norte, and
Trinity counties 5-10 degrees below normal. Low 40s along the coast
and mid-to-high 30s in interior valleys. Frost is possible in some
of the colder interior valleys of Humboldt and Trinity counties
Monday morning. Temperatures will warm back to near-normal by mid
next week as a ridge builds back in.

There is some uncertainty midweek on the prevailing pattern, as a
series of shortwaves looks possible in the Pacific Northwest, but
the probability of reaching California is below 10%. There is more
agreement on a stronger trough moving in late week into the weekend,
with better probability to see some minor precipitation. JB


&&

.AVIATION...Marine stratus has currently been eroded by mid-level
northerly winds as a weak surface front drops into NorCal.
Conditions have finally reached VFR at CEC while strong winds has
been keeping the returning southerly flow and associated stratus
layer away from the terminal. Gusts 20-35kt out of the north are
likely for the coastal terminals this afternoon causing the cloud
deck to dissolve out of Humboldt Bay. Mid-level (2500ft AGL) winds
are flowing offshore through most of the forecast period along the
Del Norte coast, possibly leading to compression heating prohibiting
a stratus resurgence later this evening and into tomorrow early
morning. Model guidance is showing a 20-30% of the clouds returning,
this is unlikely but not entirely out of the question. At KACV, the
upper winds winds are more onshore, which could possibly allow the
stratus to reform in the Humboldt bay area up to Patricks Point, yet
again more like it does not. This is supported model probability
showing a 15-45% of clouds below 3000ft reforming late tonight into
tomorrow morning. If the marine stratus were to return, it would not
start until midnight tonight or early tomorrow morning.

Meanwhile in the UKI valley, VFR conditions are prevailing with
light winds that will shift to the north as the day continues.  IFR
ceilings and reduced visibility`s will likely continue through the
afternoon. Model guidance currently showing a chance (30-55%)
probability of a surge of moisture flowing up the Russian River
valley which could lead to IFR/LIFR conditions if this manifests
itself up to KUKI. Forecast confidence on this event developing
remains low as numerical model guidance struggles to pick up these
southerly wet surges.


&&

.MARINE...Northerly gales are expected to persist across the outer
waters today, producing hazardous 10-12 foot short period waves
across all zones. Hi-Res models are still forecasting gusts of 35-45
knots late tonight and into Saturday across the outer waters as the
coastal jet peaks in intensity. Significant wave heights to 15 feet
at 10-11 seconds are expected in response early Saturday into
Sunday. Steep and dangerous seas will continue through at least late
this weekend as gales persist in the outer waters. Current model
guidance indicates the strongest winds and wave response shifting to
the southern waters on Sunday before another resurgence of gales
early next week.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Hazardous Seas Warning until 4 AM PDT Sunday for PZZ450.

     Small Craft Advisory until 9 PM PDT this evening for PZZ455.

     Hazardous Seas Warning from 9 PM this evening to 4 AM PDT
     Sunday for PZZ455.

     Gale Warning until 4 AM PDT Sunday for PZZ470.

     Gale Warning until 10 AM PDT Sunday for PZZ475.

&&

$$

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https://www.weather.gov/images/eka/zonemap.png