563
FXUS66 KEKA 271206
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
506 AM PDT Thu Jun 27 2024

.SYNOPSIS... An upper level disturbance will produce marine stratus,
patchy coastal drizzle, and relatively cooler temperatures today.
Lower daytime RHs and slightly elevated windsexpected in interior
Trinity, Mendocino and Lake County. Warming and drying trend
returns Friday, potentially becoming more intense next week.


&&

.DISCUSSION...Elevated wind gusts are still being observed across
eastern portions of Trinity and Lake counties this morning in the
wake of a weak frontal boundary. Prominent NW flow will drive
diurnally driven winds today as high pressure builds in from the
Pacific, enhancing the thermal trough and coastal pressure
gradient. With a surge of moisture into the coast contributing to
the still 3000 foot marine layer overnight, disorganized offshore
stratus is expected to linger this morning before scouring out
this afternoon with increasing marine winds and diurnal heating.
Patchy coastal drizzle is also possible this morning, especially
around Humboldt Bay.

The remaining influence of a broad upper shortwave system will
continue to contribute to cooler temperatures today. Highs are only
expected reach the mid 70`s to low 80`s across the interior while
coastal highs continue to be slightly dampened by marine stratus.
NBM anticipating some valleys in southern Mendocino, Lake and
eastern Trinity counties to rise into the upper 80`s, although
probabilities significantly fall off at 90 degrees. Minor upper
instability and moist onshore flow may allow for more drizzle within
coastal stratus Friday morning.

Broad, weak ridging is expected build into the region Friday,
driving interior temperatures back into the 90s. NBM exhibits high
probabilities of interior valleys >90 degrees on Friday, aligning
with short range deterministic models. With increasing temperatures,
min daytime RH values can be expected to drop into the mid teens and
low 20`s in Lake and interior Mendocino and Trinity counties. Moist
NW flow will sustain marine influence for coastal counties through
this weekend. Additional upper shortwaves will provide similar
disturbances this weekend before potential for substantially warmer
and drier conditions early next week. Long-range models indicate
anomalous warm ridging building into the eastern Pacific, coupled
with potential for min RHs in the teens and single digits by mid-
week. Stay tuned for updates on potentially elevated fire weather
conditions.



&&

.AVIATION...Coastal stratus has redeveloped along the Redwood Coast
overnight, and expanded well up the adjacent river valleys.
Although, profilers data indicate the marine layer is quite
shallower than previous night. Mainly MVFR ceilings with OVC layer
between FL010-FL015 at ACV and CEC early this morning...with brief
periods of IFR ceilings at CEC. Otherwise, a dry air mass moving
into our area along with increasing northerly are expected by late
morning and afternoon as a weak ridging builds in. While VFR
conditions prevail at UKI, stratus are expected to lift and mix
out with the increasing northerlies during the morning hours.
After 17Z, VFR conditions are expected for all aerodromes. Winds
from NNW at 5kt this morning, increasing to around 10-20 kt with
occasional strongest gusts after 20Z. Short-term model guidance
suggests stratus redeveloping again around Humboldt Bay and
vicinity later this evening.


&&

.MARINE...Fresh breezes will continue increasing in coverage south
Cape Mendocino this morning. Northerlies strengthen and spread from
south to north across the coastal waters this afternoon into Friday,
with the strongest winds across the southern outer waters and
leeward Cape Mendocino. Wind driven seas will generate steep short
period NW seas around 6 to 9 feet across the southern waters today.
Winds are forecast to ramp up on Friday with near gale to locally
gale force gusts across the outer waters and in the fan of Cape
Mendocino on Friday. Short period seas will pick up to around 8 to
10 feet at 8 to 9 seconds Friday afternoon as result. Winds
slightly diminish from north to south throughout the weekend as
another upper level trough moves over the area. However, elevated
northerly winds and steep seas will persist over the southern
waters.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 9 PM PDT Saturday for PZZ455-475.

     Small Craft Advisory from 11 PM this evening to 3 PM PDT
     Saturday for PZZ470.

&&

$$

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