856
FXUS66 KEKA 201446
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
512 AM PDT Fri Sep 20 2024

.SYNOPSIS...Key messages include stronger north/northwest wind
over the waters today and breezy conditions along the coast.
Gradual warming over the weekend and into early next work week,
then turning cooler Wednesday.

&&

.DISCUSSION...

Ensembles reveal an upper trough being edged out by an
approaching ridge from the west northwest. NBM forecasts a most
likely scenario of maximum wind gusts of 25 to 35 mph from the
northwest along much of the coast. Calibrated NBM probabilities give
about a 50 percent chance of wind gusts topping 25 mph at Arcata and
100 percent chance at Crescent City, with strongest peak gusts more
likely centered around 3-5 PM PDT this afternoon. May want to keep
an eye on Crescent City as the chance of the peak wind gusts over 35
mph there are 75%, dropping to about 5% chance of reaching gusts of
40 mph at Crescent City. Overall high confidence with these peak
wind gust forecasts as ensemble solutions are relatively close to
each other..

Looks rather warm Monday and Tuesday, especially along the coast,
relatively and climatologically speaking. Comparing ensembles to
climatology, Monday and Tuesday look rather warm, and especially for
the coast (relatively speaking, considering climatology), and
Tuesday in particular stands out between the two days. At Arcata, we
stand a 60% chance of reaching 70 degrees or more and 80% chance of
hitting 75 or more for Tuesday (mean ensemble solutions give a
stronger indication of offshore flow for Tuesday.

Look for a noticeable cooling for Wednesday with highs on the coast
closer to normal in the 60s and interior valley topping out in the
80s to around 90. The cooler weather will keep going for the work
week. /MH

&&

.AVIATION...A thin layer of low ceiling, foggy marine stratus has
established itself right along the NW California coast and within
the coastal river valleys. Degraded visibilities and low ceilings
are showing LIFR conditions at the coastal terminals and should
remain as such for most of the morning. NBM model guidance is
currently showing a drop in the probability of stratus through the
day with a 12% chance of ceilings <500ft AGL and 30% chance of any
cloud coverage at all sticking around by 2200Z at KACV. These
probabilities tell that the coastal clouds will most likely
dissipate entirely from the terminal spaces during the day. HREF low
cloud coverage probabilities also supports this scenario. This
evening, elevated winds will flow offshore, possibly keeping the
coastal terminals clear of stratus. However, there is a 45% chance
that low clouds will return to KACV by the early morning hours of
tomorrow. In addition, notable wind shear at the marine layer/free
atmosphere boundary is forecasted due to both directional and speed
differences between layers at KACV and KCEC.

KUKI shows its similar pattern of daytime winds from the W/NW before
dying off at or around sunset (0200Z). Some extremely high-
resolution models suggest breezy winds (10-15kts) along the mountain
ridges inland, which could possibly mix down into the terminal space
creating the increasing in the forecast for daytime winds our of the
NW. No cloud layers are forecast to develop over the inland areas,
leading to VFR conditions inland.


&&

.MARINE...Strong northerly winds (>20kts) are forecast to remain in
the outer waters today. These winds are creating steep wind waves
and conditions that warrant a small craft advisory in all the
coastal waters before upgrading to a Gale Warning at 9am this
morning. This Gale warning is a response to substantially model
guidance agreement of a low-level jet (winds at 925mb 40-50kts)
building over our waters from this morning through Saturday
afternoon. These LLJ winds have a good chance to mix down to the
ocean surface with high-resolution models showing sustained
northerly winds speeds reaching just under 35kts & gusts possible up
to 40kts. Wind waves in the outer waters for this time period are
forecast to ramp up as well due to surface winds with certain areas
currently forecasted to max out around 14ft@10s. These windy and
wavy conditions could warrant an extended marine hazard statement
for Saturday morning into the weekend. More confidence on these
details will be available within the next 12-24hrs as observations
verify the true strength of the winds allowing more high resolution
models to initialize and extend through this time period of
interest.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 9 PM PDT this evening for PZZ450-
     475.

     Hazardous Seas Watch from this evening through Saturday
     morning for PZZ450.

     Small Craft Advisory until 9 AM PDT Saturday for PZZ455.

     Small Craft Advisory until 9 AM PDT this morning for PZZ470.

     Gale Warning from 9 AM this morning to 9 AM PDT Saturday
     for PZZ470.

     Gale Watch from this evening through Saturday morning for
     PZZ475.

&&

$$

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