Hidden Valley Lake, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

295
FXUS66 KEKA 062136
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
236 PM PDT Mon Apr 6 2026

.SYNOPSIS...Dry weather and above normal high temperatures are
expected to continue in the interior through Tuesday. Chance for
showers and interior thunderstorms will arrive on Wednesday and
then increase on Thursday. Chance for showers and thunderstorms
will continue on Friday and possibly into the weekend.

&&

.DISCUSSION...Massive field of stratus offshore has been banked up
against the coastline today. Marine layer was shallow (<1 kft MSL)
but has been deepening today. Layer should continue to deepen
tonight and push farther into the adjacent coastal river valleys.
The stratus forecast has been nudged toward persistence, based
largely on high boundary layer humidity from the ARW and NAM12.
Otherwise, dry weather and above normal high temperatures (70s to
lower 80s) are forecast to continue for much of the interior on
Tuesday as a ridge aloft springs up in advance of an approaching
500mb trough. Cool-damp marine air will continue to result in
cooler weather for coastal locations and adjacent river valleys.

Rain shower chances increase on Wednesday as SWLY flow aloft
moistens up in advance of a closed 500mb low that will approach
130W around 39N. Slight upper diffluent flow aloft (positively
tilted) develops over the area through the day and the atmosphere
does appear to destabilize some with long thin CAPE around
200-500J/kg, lifted indices near -1C and PWATS near 200% of
normal. Thunderstorms are possible (15% chance) with daytime
heating for mostly eastern Trinity, eastern Mendocino (over the
Yolla Bolly`s) and perhaps far northern Lake.

Potential for interior showers and wet thunderstorms are forecast
to increase on Thu as the cut-off low moves inside 130W and stronger
500mb S-SE flow develops while PWATS remain near 200% of normal.
Forcing with a perturbation pin-wheeling around the offshore low
coincident with max daytime heating should result in stronger
multi-cell storm clusters with greater potential for heavy
rainfall, small hail and perhaps gusty winds. Large scale 500mb
flow is favorable for storms to propagate out over the coast and
coastal waters as S-SE SFC-500mb bulk shear increases to 30-40kt.
Most likely time period for coastal thunder would be Thu night
into Fri morning if storms fire up with daytime heating over the
interior. One caveat to all of this is boundary layer destabilization.
If surface temperatures cool down too much due to cloud cover and
widespread showers, there may not be enough boundary layer
destabilization for storm initiation. Other than the potential
for locally heavy rain with thunderstorms, not very much rain is
expected over 3 days with the incoming cut-off low, generally less
than 0.25 to 0.50 inches Wed-Fri. Higher amounts near 1 inch over
3 days (Wed-Fri) are certainly possible with strong/deep moist
convection over the interior.

Wrap around moisture with above normal precipitable water over
200% of normal will keep the threat for showers and thunderstorms
going into Friday. Beyond Friday into next weekend, wet and cooler
weather may return on Sat as an upstream and potentially much
colder trough comes barreling down from the NW. This trough could
bring a chance for snow to the highest mountain peaks too this
upcoming weekend. There are considerable differences in the
ensembles and other outcomes are possible, including a warmer
and drier scenario.

&&

.AVIATION...IFR and LIFR ceilings have been steady at KACV and
KCEC through the day. A brief break up of the solid stratus deck
is possible, but confidence is waning quickly based on satellite
imagery and BUFKIT time-height sections which indicate the layer
gradually deepening tonight. Mesoscale models, particularly the
ARW, indicates near full saturation of the boundary layer (99% RH)
this evening and fog with vsby 1/4SM or less may come charging
back in with light onshore winds. Easterlies overnight may
mitigate the fog threat overnight as the layer lifts or drizzles
outs. Chances for IFR clouds pushing up from Sonoma County and
into Ukiah Muni is not looking very likely at this point unless
the marine layer deepens considerably. Marine air will trickle
into interior Mendo from the west and low clouds and fog should
form with longwave cooling north of UKI around Willits.

&&

.MARINE...Marine winds and seas are forecast to remain below advisory
thresholds for small craft through the week (Tue-Fri). Northerlies
and larger steep waves should begin to build over the weekend
(Sat and Sun) after passage of a cut-off low to the SE and surface
ridging offshore builds. Primary hazards to navigation will
continue to be the "patchy fog" and perhaps thunderstorms latter
in the week that could propagate over the waters in the wrap
around east-southeast flow, specifically Thu night into Friday.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
None.
&&

$$

NOTE: The full forecast discussion is now regularly issued between
10 am/pm and 1 pm/am. Additional updates will be issued as needed.

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