639
FXUS66 KEKA 310751 CCA
AFDEKA

AREA FORECAST DISCUSSION...CORRECTED
National Weather Service Eureka CA
1251 AM PDT Sun Aug 31 2025

.SYNOPSIS...Near seasonal average temperatures will continue
through the weekend. A warming trend will increase the HeatRisk
and fire weather threat as low RH and hot temperatures build
across the interior on Monday and then peak on Tuesday. The coast
is expected to see night and morning clouds with some afternoon
clearing most days. There is a slight chance of thunderstorms on
Tuesday in the interior.

&&

.DISCUSSION...The upper level low continues to remain nearly
stationary off the Pacific Northwest coast. This continues to
bring mostly sunny skies and moderate seasonal temperatures. The
cooler air aloft continues to keep the marine inversion weak
allowing stratus clearing in the afternoon. This pattern is
expected to continue today with highs in the upper 80s to mid 90s
across the interior. Monday high pressure starts to build in from
the south and push the upper level low north. This will warm
inland temperatures by around 5 degrees. This will also strengthen
the marine inversion and coastal clouds may be a bit more
prevalent.

Southwesterly winds aloft will continue to push the smoke from the
active wildfires in Siskiyou and Trinity counties toward northeast
out of the area through Monday. The exception will be areas north
of the Peak Fire between Trinity Lake and Granite Peak. There
will likely be local terrain effects that will continue to bring
smoke to the valleys in all directions near the fires. This will
be especially true if the fire is burning below the inversion and
the smoke is trapped. For details visit weather.gov/eka and check
out the area smoke forecast on the bottom of the main page.

Tuesday the forecast gets a little more tricky. A shortwave
moving up the west side of the ridge and this may bring some
moisture and instability. There is the potential for thunderstorms
across the interior due to this. There is lift from the shortwave
and steep lapse rates from the cooler air aloft. The remaining
question is if there will be enough moisture. PWATs on the models
are only progged to be around 0.60 to 0.70 inches. If any storms
do form, they will likely be fairly dry. The NAM shows storm bases
around 10,000 feet. For now will keep the slight chance for
thunderstorms across Trinity county.

Tuesday will likely be the about the hottest day of the week with
highs several degrees warmer than Monday. This is expected to
bring a moderate heat risk to the area and a heat advisory may be
needed in portions of the interior. However the models are showing
temperatures trending slightly cooler.

Wednesday the shortwave is expected to be north of the area. Even
the slower solution of the ECMWF has pushed the instability north
of the area by the afternoon ending the threat for thunderstorms.
Temperatures are expected to be similar to Tuesday. Thursday and
Friday a gradual cooling trend is expected, although temperatures
are expected to remain hot. MKK

&&

.AVIATION...As twin low pressure systems spin near and far off
of the coastline, the nearest cyclonic motion is ejecting moisture
bands towards the PACNW with most of it missing our CWA. Cirrus
clouds denote colder temps aloft but meridional flow from the north
is the prevailing cardinal direction as of 02z Saturday evening.
Models indicate that light southerly flow will fill in at KCEC early
Sunday morning, calm to light winds might usher in low overcasts
cloud decks by midnight, bringing IFR/LIFR conditions for a few
hours. Improved flight conditions by late Sunday morning at KCEC
with similar conditions at KACV with an easterly bearing that will
bring VFR sooner than Jack McNamara field. KUKI is expected to have
light northerly winds and prevailing VFR conditions. Northerly winds
could gust up by the late afternoon at KUKI 13-16kts. /EYS

&&

.MARINE...Northerly winds continue to increase in the lee of Cape
Mendocino, with gusts of 25-30 kts forecast Sunday afternoon into
the evening. Models are beginning to resolve a fetch of northerly
winds in the northern outer waters, likely to build and fill in
Monday. Small craft advisories may need to be hoisted to cover the
conditions. Stay tuned in.

Seas remain mild, with combined seas of 3ft as of Saturday night. A
small long-period southerly swell continues and will persist trough
the weekend. Higher seas building from 4 to 6 ft by Sunday evening,
south of Cape Mendocino. Stronger winds may reach nearshore
Mendocino Sunday afternoon, with gusts peaking around 25-30 kts. By
Sunday night into Monday, winds increase in the northern outer
waters. This general pattern continues into mid next week. /JB
/EYS

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from 11 AM Sunday to 11 PM PDT Monday
     for PZZ455.

     Small Craft Advisory from 5 AM Sunday to 11 PM PDT Monday
     for PZZ475.

&&

$$

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