066
FXUS66 KEKA 052041
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
141 PM PDT Sat Jul 5 2025

.SYNOPSIS...Temperatures will generally trend warmer through Monday.
There is a slight chance for interior thunderstorms Monday and
Wednesday along with slightly cooler temperatures. Hot weather
with temperatures over 100 degrees is possible by Thursday.


&&

.DISCUSSION...
KEY MESSAGES:
  -Warmer temperatures Sunday

  -Slight chance of thunderstorms Monday and Wednesday

  -Hot temperatures Thursday and Friday.

WEATHER PATTERN OVERVIEW:
High pressure is generally over the area this afternoon, however
there is a upper level low developing off the coast of northern
California. This is not expected to the impact the weather until
Monday when it gets closer and drops slightly south. Temperatures
Sunday are expected warm into the 90s in many inland areas while
the marine layer stays fairly shallow.

Monday as the low gets closer this will likely bring a stratus
surge to the coast and may cool temperatures in the near coastal
areas. This may also bring a thunderstorm or two to the Trinity
Alps. For now it looks like the best chance for thunderstorms on
Monday will be to the north of the area. Tuesday is expected to
see additional cooling with highs only expected in the upper 80s
to low 90s. The potential for thunderstorms moves north on Tuesday
and at this point it looks like it will be out of the area.
Wednesday the upper level starts to become an open trough and move
through the area. There is still quite a bit of uncertainty on
how quickly this will move out of the area, but it looks like
there is a slight chance for thunderstorms in mainly northern
Trinity county.

Warmer temperatures are expected Thursday and Friday as the
low/trough moves out of the area. Highs near or slightly above 100
are expected with Friday expected to be the hottest day of the
week.

FORECAST CONFIDENCE AND DEVIATIONS:
Sunday there is fairly high confidence in the general forecast
with a fairly typical progress of warming temperatures and
shrinking marine layer. Did blend the NBM RH Sunday afternoon with
the FV3 model bring RH down, especially in interior Humboldt and
Del Norte counties. Monday morning is expected to start off with
some offshore which may help limit the coastal clouds and allow
skies to clear out more quickly.

Monday afternoon confidence diminishes as it looks like there
will be southerly surge of winds and stratus near the coast.
Confidence is also low on the potential for thunderstorms Monday
afternoon. Increased the Potential thunder to 15 percent for
northern Trinity county to get some thunderstorms in the forecast.
The better chances look to be north of the area in Siskiyou
county. There is also a small chance some thunderstorms could
make it into Del Norte county again and push towards the coast.
The lapse rates aloft are good and there is some elevated
instability. Tuesday the low pushes back off the coast a bit and
the better thunderstorms chances are expected to be farther north
in Oregon. Wednesday the closed low is expected to become an open
wave and move across the area. This also has the potential to
bring some thunderstorms to the area with the best chances in
Trinity county. So have added a 15 percent chance of thunderstorms
which again is above the current NBM guidance. Confidence is
still low on the exact location and timing. Overall this is a very
tricky pattern and the location of the thunderstorms depends
highly on the exact track of this upper low which is a low
predictability type of event. There is a small chance that
thunderstorms could develop in most any part of our area over the
Monday through Wednesday time period or we may see none and they
are all north of the area.

Thursday and Friday confidence is much higher that we will see
warming temperatures with a 60 to 80 percent chance of the inland
areas seeing temperatures exceed 100 degrees and seeing a moderate
to locally major heat risk. MKK

&&

.AVIATION...Ceilings are beginning to lift and scatter along the
north coast this afternoon. Broken MFR ceilings expected briefly
after 00Z for ACV while CEC maintains a longer period of VFR
conditions. Otherwise, NW flow will continue through the evening
with gusts 10 to 15 knots possible at UKI. Stratus expected to
redevelop along the coast with IFR to LIFR ceilings and viz
overnight as the marine layer compresses, especially near sunrise.
Light offshore flow expected at the coastal terminals; HREF indicate
this will have little effect on the marine layer through the
morning. Probabilities for ceiling coverage fall below 50% after 18Z
Sunday.

&&

.MARINE...Northerlies are expected to strengthen again today, with
gusts 20 to 30 knots developing in the outer waters this afternoon
into Sunday morning. High confidence in near gale gusts continuing
south of Cape Mendocino as Gale conditions develop and become
confined to the northern waters during the day Sunday. Gusts
approaching 40 knots are possible as the strongest winds develop
late Sunday into Monday morning. Steep and hazardous wind waves 9 to
12 feet are forecast in response to these winds, potentially
propagating into the northern inner waters briefly. Conditions will
quickly diminish on Monday as a closed upper low cycles off the CA
coast.

&&

.FIRE WEATHER...High temperatures are forecast to warm more on
Sunday. Overnight recoveries are generally expected to remain good
except for a few exposed ridges where low RH`s may persist
through the night. Sunday night into Monday some offshore flow is
expected to help keep the marine clouds and moisture out of the
area and there may be some lower recoveries in northern Humboldt
and Del Norte counties. Monday afternoon or evening the marine
layer is expected to return near the coast with some southerly
winds as an upper level low approaches the area. This also brings
an isolated threat for thunderstorms. This threat is expected to
continue through Wednesday, for details see the forecast
confidence section.

The upper level low is forecast to finally eject N-NE by mid next
week as a massive ridge over the four corners region expands over
the area. Much hotter temperatures and drier humidity are highly
probable in the interior late next week. There is a 60 to 80
percent chance of inland valley temperatures exceeding 100 degrees
by Friday. RH is also expected to be low.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from 5 PM Sunday to 9 AM PDT Monday
     for PZZ450.

     Small Craft Advisory until 3 PM PDT Sunday for PZZ455.

     Small Craft Advisory from 8 PM this evening to 3 PM PDT
     Sunday for PZZ470.

     Gale Warning from 3 PM Sunday to 3 AM PDT Monday for PZZ470.

     Small Craft Advisory until 3 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.

Visit us at https://www.weather.gov/eureka

Follow us on Facebook and Twitter at:
https://www.facebook.com/NWSEureka
https://www.twitter.com/NWSEureka

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