Manchester, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

401
FXUS66 KEKA 201928
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1228 PM PDT Sun Jul 20 2025

.SYNOPSIS...Another warm day is expected in the interior today with
stratus and fog likely along the coast. Cooler conditions expected
Monday and Tuesday, with a low chance of rain for the area.


&&

.DISCUSSION... Temperatures in the mid 90`s expected again today across
interior valleys. Smoke may inhibit high temperatures slightly,
especially in eastern Humboldt. Gusty westerly winds expected in
eastern Lake and Trinity as an upper trough approaches the region,
tightening the coastal pressure gradient. Gusts 20 to 30 mph
expected south of Cape Mendocino(SW flow in higher elevations of
eastern Lake County). This will pose a slight fire weather concern
as daytime RH`s are still 25 to 30%. Much of the marine stratus
layer will be scoured out by increasing northerlies offshore this
afternoon before redeveloping and deepening overnight into
Monday.


High pressure will begin to break down beginning Monday as a
positively tilted upper trough over WA/OR begins to extend into
NorCal. Temperatures are expected to cool off significantly with
highs in the upper 70`s to mid 80`s (with isolated valleys of
Trinity County potentially reaching 90) through midweek. Long range
models show anomalously low heights sitting over the eastern
Pacific/PNW through late this week. Light rainfall is possible
Monday afternoon as the trough axis drops into NorCal with an
associated weak cold front. Probabilities for >0.01 inches exceed
50% for coastal Humboldt and Del Norte as well as northern Trinity,
but chances for wetting rain are minimal and isolated.

Mid-level moisture and cooler upper temperatures may contribute to
thunder potential as well beginning Tuesday afternoon, especially
for the upper Trinity horn. Confidence is still low on this as
instability is minimal. Convective potential increases Wednesday
with increasing surface temperatures/instability as the upper trough
gradually cuts off and closes off the coast. This may allow storms
to develop and push further west into eastern Del Norte, northern
Trinity and eastern Humboldt. Thunder potential continues for
this area through the end of the week (10 to 20%).



&&

.AVIATION...A narrow band of stratus remains along the coast.
Northwesterly flow will erode this band at CEC and ACV in the
next couple of hours leaving VFR. South of Cape Mendocino full
clearing will be more challenging today. Inland VFR is dominating
except for valleys around Orleans where smoke is impacting
visibilities. An upper level trough will move over Northwest
California overnight bringing increased moisture and a deeper
marine layer. Clouds will expand again along the coast overnight
and push into the coastal valleys, likely farther inland than last
night. Drizzle or even light rain will be possible along the
coast where high resolution guidance is showing the potential for
a few hundredths of an inch. /RPA


&&

.MARINE...Northerly winds are peaking today south of Cape Mendocino as the
pressure gradient is pinched between an area of high pressure over
the eastern Pacific and a trough dive south from the Pacific
Northwest. This trough will result in pushing the surface high back
west eventually weakening the gradient over the coastal waters and
reducing wind speeds. The trough will then become cut-off over
Northwest California, spinning aloft for the next several days.
Light northerlies are persist through the work week but remain well
below small craft criteria as the low spins and eventually moves
northeast out of the area next weekend. /RPA


&&

.FIRE WEATHER...Temperatures remain warm again today with
afternoon RH in the 20`s and 30`s with generally good RH
recoveries outside the highest elevations. Breezy west-
northwesterly winds are forecast both today and Monday for the
interior areas, with the strongest winds likely in eastern Trinity
and Lake counties. In southern Lake County, winds are still
breezy but mainly from the west-southwest. Peak gusts of 20-30 mph
are possible, bringing locally elevated fire weather conditions.

Poor air quality persists for interior Humboldt and northern Trinity
County due to the Butler Fire. Some improvement in air quality is
possible in the afternoon with greater mixing except immediately
downwind of the fire.

An approaching trough is expected to deepen the marine layer Monday.
A weak cold front will bring the low chance for light rain to the
area, with the highest chances in Del Norte and eastern Trinity
County. Wetting rain is unlikely, but if there is any, the highest
chances are in eastern Trinity county. A few showers are possible
Monday afternoon in the Trinity Horn, but thunderstorm chances
remain low at around 5-10%. Tuesday and Wednesday afternoons have
similar confidences, with higher probabilities in Siskiyou county.
Thunderstorm chances increase later in the week, but still
confidence remains low.



&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 AM PDT Monday for PZZ455-475.

&&

$$

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