497
FXUS66 KEKA 190751 AAC
AFDEKA

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Eureka CA
1251 AM PDT Thu Jun 19 2025

.SYNOPSIS...Gusty and locally strong coastal northerlies through
Thursday. Stronger west and northwest winds expected for the
interior Thursday through Friday. Much cooler with below normal
temperatures for the interior Friday and Saturday.

.KEY MESSAGES:

* Elevated to locally critical fire weather conditions Thursday and
  Friday for Lake, eastern Mendocino and eastern Trinity Counties
  due to low RH`s and stronger west and northwest winds.

* Gusty and locally strong coastal northerlies Thursday.

* Much cooler Friday and Saturday in the interior, followed by a
  warming and drying trend early to mid next week.


&&

.DISCUSSION...Interior high temperatures forecast to trend down
on Thursday, but it will still be hot with highs in the 80s.
Interior temperatures are forecast to drop well below seasonal
averages (by 15-20F degrees) Friday and Saturday, and then recover
slightly on Sunday.

Increased chances Thursday for higher chances for gusts to 30-40 mph
along the Mendo coast, SW Mendo and higher elevations (above 1500-
2500 ft) in Lake County during the afternoon and evening. NBM
remains much lower with zero chances for gusts to 40 mph except for
the ridges of SW Humbodlt.

Prime concern heading into Thursday and Friday will be stronger west
and northwest winds across the interior. Gusts to 20-30 mph are
probable (60-70% chance). Higher terrain and ridges may even gusts
35-50 mph as an unseasonably cold 500mb low drops down from the Gulf
of AK on Friday. Friday looks to be the strongest wind day. Humidity
generally increases as we head into Friday. Portions of Lake,
eastern Mendocino and eastern Trinty will likely have lower humidity
- around 20-25% on Friday. With the trough enhancing diurnally
westerly and northwesterlies breeze on Friday, elevated to locally
critical fire weather conditions are forecast. Risk for small and
fast spreading grass or brush fires will increase. Winds may not
line up exactly with low RH`s for 8 hours or more for a red flag
warning. Now a few windier higher elevations will probably reach or
exceed 8 hours with these stronger winds on Friday even with
slightly higher humidities.

This upper trough/surface front will probably generate some light
rain for the northern most zones; Del Norte and northern Humboldt
Friday afternoon and evening. Generally around 0.10 to 0.25 inches
of rain are forecast for Del Norte County with a few hundredths for
northern Humboldt. Model soundings continue to show some buoyant
energy along the far northern portion of our coastal waters and Del
Norte county as 500mb temps dip down to minus 25C or less. Soundings
show low EL`s (equilibrium levels) and very narrow CAPE with WNW
flow through the column. Thus not convinced there will be any
thunder in our area. Calibrated guidance show higher chances north
of the ORCA border with passages of a shorter wavelength trough. Not
very much rain overall is expected, but just enough to have impacts
on any outdoor activities and projects Friday afternoon and evening.

Additional perturbations in N-NW flow on the backside of an upper
level trough may generate isolated showers over the weekend,
primarily for Del Norte and Trinity. Otherwise, dry and cooler
weather is forecast to prevail into the weekend. If skies clear out
and winds go calm, patchy early morning frost will be possible (45%
chance) for interior valleys; primarily Trinity County (Hayfork) and
NE Mendo (Covelo). A warming trend is forecast early to mid next
week with highs in the lower to mid 90`s by Wed. A warmer scenario
is possible if 500mb heights pump up to 588DM. This warmer outcome
would propel max temps to 100F in valleys of Lake, interior Mendo,
NE Humboldt and Trinity. Big Bar RAWS for sure will hit 100-105F by
Wed next week. Otherwise, no clear signs for a major heat wave
(highs temps to 110F or more).



&&

.AVIATION...06Z TAF: Gusty north winds are expected to continue
into Thursday with gusts 20 to 30 knots expected to continue with a
strengthening coastal pressure gradient. Signs of a return of
coastal stratus is already apparent via the night fog satellite
view. Winds for more sheltered terminals will die down into early
Thursday morning but remain elevated just offshore, perhaps
lingering at CEC. Gusty winds will pick back up over the region
Thursday afternoon. Greater probabilities for widespread VFR
conditions are expected for Thursday as a low pressure system
approaches the region and disrupts the high pressure ridge.


&&

.MARINE...Fresh to strong breezes producing steep and hazardous wind
waves are expected through Thursday, with gales likely and isolated
gusts approaching 40 knots possible in the southern outer waters and
downwind and nearshore of Cape Mendocino. Strongest winds are
expected to develop into early Thursday morning. Near gale to gale
force gusts may push further into portions of the inner waters
Thursday afternoon. A small mid-period NW swell 4-5 ft at 14 seconds
will contribute to the sea state Thursday afternoon, producing
combined seas 8 to 10 feet. The sea state will begin to diminish on
Friday as a low pressure system approaches the region, disrupting
the wind pattern. Gentle to moderate breezes expected early this
weekend before increasing again in the southern waters.

&&

.FIRE WEATHER...Stronger westerly and northwesterly winds are
expected Thursday through Friday as an unseasonably cold upper
trough moves across the Pacific NW (Washington and Oregon). With
minimum RH`s around 20-25% on Friday and gusty afternoon and evening
winds, elevated to locally critical fire weather conditions are
anticipated for eastern Trinity, eastern Mendocino and Lake
Counties. Duration of these red flag conditions are not forecast to
be long-lived for most of the area. Some higher elevation exposed
ridges will likely remain very dry and windy with over 8 hours of
red flag conditions.

A couple of northerly speed maximums over the Sacramento valley may
graze Lake County Saturday and again Sunday. Low overnight humidity
over the higher terrain of Lake County may yield locally elevated
fire weather conditions. Otherwise, daytime minimum humidities are
forecast to trend drier over the weekend into mid next week as
temperatures increase each day.



&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 9 PM PDT this evening for PZZ450-
     470.

     Small Craft Advisory until 9 AM PDT this morning for PZZ455.

     Gale Warning from 9 AM this morning to 9 PM PDT this
     evening for PZZ455.

     Gale Warning until 3 PM PDT this afternoon 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