983
FXUS66 KEKA 052111
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
211 PM PDT Thu Jun 5 2025

.SYNOPSIS...Gusty northerly winds will continue to diminish
through Friday, however steep elevated seas over the coastal
waters will continue. Hotter weather is expected this weekend and
early next week in the interior. Thunderstorms in the Klamath
Mountains region of California possible Sunday and Monday.

&&

KEY MESSAGES:

- Strong gusty northerly winds and steep elevated seas over the
  coastal waters to diminish on Friday. Lighter winds expected
  over the weekend.

- Moderate HeatRisk expected to increase this weekend with hotter
  afternoon temperatures in the interior through Monday.

- 20% chance for thunderstorms Klamath Mountains Sunday and
  Monday.

- Gusty northerly winds strengthening over coastal areas and
  coastaL waters early to mid next week.

&&


.DISCUSSION...

Warm and dry weather conditions will persist for the interior
through Friday as a ridge aloft over the northeastern Pacific
folds over into the Pac NW on Friday Slightly warmer than average
high temperatures are expected to continue on Friday in the interior.
Marine air and stratus will keep coastal areas much cooler. It may
not even break 60F for coastal areas through this weekend.

Moderate HeatRisk is forecast to expand in coverage over the
weekend as the southern edge of a 500mb height anomaly builds
over the Pac NW; Oregon and Washington. With 850mb temps soaring
to 22C or more, many of the warmer locations in Trinity and NE
Humboldt Counties will reach 100-102F this weekend. Granted Big
Bar Raws will probably be hotter; 106-108F. The robust N-NE flow
is forecast to abate over the weekend and marine air and stratus
will most likely mitigate the HeatRisk for western portions of
Mendocino, Humboldt, and Del Norte Counties. Marine air intrusion
via the Russian river valley and southerly winds will probably
keep southern Mendocino from getting to 100F this weekend. It will
still be hot and we will continue to message heat and river
safety rips in weather story graphics.

Another potential impact going into the weekend into early next
week will be a low chance (10-25%) for diurnally triggered and
terrain forced thunderstorms over the Klamath Mountains region of
California. A semi-closed low aloft (700-500mb) is forecast to
bring an increase in mid level humidity and E-SE flow Sat-Sun. GFS
has trend with higher CAPE and instability over NE Trinity
mountains as early as Sat, however the soundings look super dry in
the lower atmosphere. Convective parameters for storms increase
on Sunday and more so on Monday per the GFS model. It will still
be really dry in the lower atmosphere and with 100F degree heat
bubbling up in afternoon a few updrafts could break through the
mid level stable layer. Once convection begins the storms may
spread NW into Del Norte County Sunday night into Monday morning.
Confidence in this scenario more than 4 days out is not high with
no clear signal for a forcing mechanism from the weak mid level
cyclonic circulation. The storm and lightning activity may end up
farther west (out over the coast) than what we may believe looking
at the NBM or SREF thunder probabilities.

Mid level cyclonic circulation is forecast to slowly meander
across the area early to mid next week. Moisture does not look to
be in abundant supply. Main impacts appear to be CG strikes and
gusty outflow winds given inverted-V profiles indicated by the GFS
model. NBM 12hr thunderstorm probabilities do increase over the
weekend into early next week and we will begin to ramp up the
messaging for low chances of storms in a weather story graphic.

Potential for more storms on Tue diminishes, however models
continue to struggle with the rate of progression of a semi-closed
low and another upstream shortwave trough in the westerly flow.
Thus storm chances seem on the fringe of possibilities in far NE
Trinity on Tue. Brief ridging on Tue may be followed by a deeper
trough Wed and Thu next week. This trough looks quite dry and main
impacts appear to be a return of stronger gusty winds.

&&

.AVIATION...

Stratus has lifted and scatter early this afternoon, at least for
the Humboldt coast, but stratus will make a return this evening.
Gusty northerly winds continue at CEC, but will finally ease this
evening, and turn southerly late evening into early Friday.
Stratus will likely reform first around Humboldt Bay then advect
northward to CEC with the southerly winds with LIFR/IFR ceilings
and visibilities possible. Southerly winds in UKI brought stratus
in this morning, and HREF is hinting at the possibility again of
IFR/LIFR ceilings. Models begin to diverge on stratus remaining
through the day Friday for the coastal areas. NBM is showing
around a 35% chance for all-day stratus at CEC and ACV. JB

&&

.MARINE...

Near-gale to gale force northerlies continue in the northern outer
waters and around Pt St. George. Nearshore winds have turned light
and southerly, though some northerly breezes will likely sneak in
this afternoon off the Humboldt coast. Seas remain steep and hazardous
south of the Cape, even as winds have started to ease. Winds and
seas gradually ease tonight into Friday, with stronger winds (20-30
kts) constrained to 50-60 nm offshore. Winds this weekend weaken
further, with gentle to moderate breezes forecast across the
waters. Northerlies increase again early next week. JB

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 PM PDT Friday for PZZ450.

     Gale Warning until 3 AM PDT Friday for PZZ470.

     Hazardous Seas Warning from 3 AM to 11 AM PDT Friday for
     PZZ470.

     Hazardous Seas Warning until 11 PM PDT this evening 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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