958
FXUS66 KEKA 010802
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
102 AM PDT Tue Jul 1 2025

.SYNOPSIS...Scattered Thunderstorms are most likely again Tuesday
afternoon in the interior. Slightly cooler conditions will build
midweek with a deep marine layer settling along the coast.


&&

.DISCUSSION...Over the past 24 hours, low
pressure along the central California coast has pulled moisture up
the Sacramento Valley and up over the coastal mountains. Moisture
combined with robust solar heating helped create scattered
thunderstorms across the interior mountains. Storms moved towards the
coast with lightning all along the coast between Orick and Crescent
City. Peak gusts were observed up to 60 mph with observed hail of up
to 0.8 inches. Some stations reported up to 0.5 inches of rain
though precipitation was spotty at best.

A similar pattern will continue Tuesday as low pressure continues to
move inland. Robust heating will remain over the interior with highs
in the upper 90s. A very thin marine layer will remain at the coast
with shallow fog in the morning hours. Another round of
Thunderstorms is likely (30%) Tuesday afternoon. In comparison to
Monday, steering flow and shear is much weaker, likely making storms
much more attached to the terrain. Convective models suggest the
most likely location for storms to from will be over Southern
Trinity County and Northern Mendocino County (especially the Yolla
Bollys). Though chances are lower (15%) there remains potential for
some thunderstorms in interior Humboldt and Del Norte. Again, low
level dry air will help enhance outflow (up to 50 mph) and increase
the risk of fire starts. That said, reduced shear will help storms
be shorter lived with less hail potential.

Beyond Tuesday, a deep trough draping across the area will bring
cooler temperatures with interior highs in the 80s. A deep marine
layer will likely help maintain cloudy and cool marine conditions
with highs int he low 60s. Persistent onshore flow and an elevated
marine inversion will help pull marine influence further inland.
Weak high pressure will gradually return this weekend, though no
more than moderate Heat Risk is expected through the weekend. /JHW


&&

.AVIATION...0Z TAFs...

Key Points:

-Scattered interior thunderstorm activity Tuesday

-High probability for LIFR CIGS and VIS through this period

The very active thunderstorm activity which started in the interior
and made its may to the Far North Coast this evening subsided Monday
night. Isolated nocturnal activity may also reform. Scattered
thunderstorms will redevelop Tuesday afternoon over mainly the
interior. These storms will be capable of abundant lightning, gusty,
erratic winds, and hail.

The cutoff mid to uppper-level low responsible for bringing the
ingredients for this activity remains south of the area. With the
instability higher aloft, and some subsidence modeled on the
northern periphery of the low, there is a very high probability for
LIFR CIGs and VIS for the coastal terminals through this 0Z TAF
period. Chance for CIGS to further lower with visibility at 1/2 SM
or less is moderate from 9Z to 16Z for the coastal terminals,
including south from southern Humboldt and Mendocino. Southerly flow
will likely advect stratus up the Russian River valley close to the
UKI terminal through Tuesday morning. Current satellite imagery
shows the stratus making a slow move north in that direction from
Sonoma County.

Model guidance is pessimistic in regard to improvement in flight
categories Tuesday. The low level inversion looks to remain somewhat
strong with the instability higher aloft. Model soundings hold the
inversion shallow with some chances for afternoon deepening and
windows of scattering Tuesday afternoon. LIFR to IFR conditions may
hold firm, but disruption of the stratus layer later in the
afternoon may occur. Chances for IFR at ACV only lower briefly to
30% after 21Z before increasing again. The added instability
encouraged more efficient mixing and afternoon wind gusts, and this
is expected Tuesday afternoon as well.

Forecast Confidence:

Chance for LIFR coastal terminals: High (75 to 93%)

Chance for Visibility less than 1SM coastal terminals: Moderate (30
to 45%) JJW


&&

.MARINE...Thunderstorms made it to the coastal waters this afternoon
and this evening. The majority of this activity has ended for the
waters. The northerly winds are on the increase again Tuesday. A
Gale Warning remains for the northern outer waters (zone 470). A
Gale Warning is now out for the southern outer waters (zone 475)
starting tuesday evening as the northerlies further strengthen
throughout the southern waters. Large, steep seas continue to
propagate into the inner waters, and these seas can periodically
pulse higher to hazardous levels. A Hazardous Seas Watch has been
issued for the southern inner zone (455) Tuesday night for a
combination of gale strength gusts and periods of steep and
hazardous seas that are expected to make it closer to the coast. The
northerlies ease some into the end of the week, but are forecast to
strengthen again through the weekend. JJW


&&

.FIRE WEATHER...Scattered thunderstorms were observed across the
northern interior areas Monday with frequent lightning and gusty
outflow winds. Another round of thunderstorms is expected to form
Tuesday afternoon. In contrast to Monday, storms will be mostly
stationary and will most likely from over Southern Trinity and
Northern Mendocino Counties. Though wetting rain is expected in
storm cores, lightning may still hit dry fuels away form the storms.
Gusty outflow winds up to 50 mph will also pose a risk for fire
spread. Outside of storms, highs will be in the mid 90s with
Minimum RH around 20 percent. Cooler and more moist conditions will
build mid to late week with highs in low 80s and minimum RH closer
to 30 percent. Northwest winds will be slightly enhanced in the
afternoon. /JHW


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Red Flag Warning from 11 AM this morning to 11 PM PDT this
     evening for CAZ203-204-211-212-277-283.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 11 PM PDT Wednesday for PZZ450.

     Hazardous Seas Watch from this evening through Wednesday
     evening for PZZ455.

     Gale Warning until 11 AM PDT Wednesday for PZZ470.

     Small Craft Advisory until 7 PM PDT this evening for PZZ475.

     Gale Warning from 7 PM this evening to 11 PM PDT Wednesday
     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