Hazardous Seas Warning 10, NWS Eureka, CA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
132 PM PDT Tue Mar 24 2026

.SYNOPSIS...A decaying front will bring a chance of light to moderate
rain to mainly Del Norte and northern Humboldt Counties tonight.
Light rain chances linger into Wednesday morning and then decrease
in the afternoon. Blustery to strong northerly winds are forecast
to develop behind the front on Wednesday and continue into Thursday.

&&

.DISCUSSION...Light to moderate rainfall will increase across Del
Norte and northern Humboldt Counties this evening and overnight.
A long southwesterly fetch of subtropical moisture (PWATS >1")
associated with a decaying cold frontal boundary will intersect
the coastal topography late today into tonight. High resolution
mesoscale models continue to show the highest chances for hourly
rates over 0.10 inches arriving late today into this evening
for coastal Del Norte. HREF 90th percentile 24-hour rainfall
exceeds 1 inch near the ORCA border while the 10th percentile
ending 5 AM Wed is on the order of half an inch. NBM has a much
larger spread with over 90 more ensemble members. Amounts from
the national blend are generally around a tenth or two on the low
end (10th percentile) but also near 1" in 24 hours on the high
end (90th percentile). The front and moisture influx will likely
weaken considerably as the boundary sags SE and rainfall amounts
will be much less for Humboldt, around a tenth or two. Some places
in southern Humboldt may not get any measurable rain at all. Rain
chances are forecast to decrease on Wed as northerlies steadily
increase offshore. Residual drizzle and low clouds may persist
into the afternoon and evening hours as chilly N-NW breezes develop.

Otherwise, dry and stable weather will continue for the remainder
of the area through the week and into the weekend. Generally
above normal high temperatures with minor heat risk is forecast
as a broad flat ridge aloft dominates. There will be slight
cooling on Wed in the wake of the cold front, however max temps
will still be above normal. The warmest locations will continue
to be in Lake, Trinity and interior Mendocino Counties where max
temps will likely warm up into the lower to mid 80s toward the end
of the week (Thu and Fri). Robust offshore flow, dry air and
clearing skies will make for exceptional longwave cooling for wind
sheltered valleys. The chance for early morning frost and
subfreezing temperatures will increase for mostly the interior
valleys Thu morning and again Fri morning. Coastal areas may also
have frost too but winds and cloud cover may hamper the cooling.
Persistent east to northeast breezes through the night will keep
the exposed ridges dry and much warmer through the night and no
frost is expected for locations in the thermal belt and along
mountain ridge tops.

Longer range models and national blend of models are trending
wetter/colder next week, Monday March 30 to Friday, April 3rd.
Higher end scenario (90th percentile) suggests multiple inches of
rain spread out over multiple days while a lower end scenario
(10th percentile) would yield only half an inch or less over
multiple days. There is considerable variability and spread 7 day
to 9 days out, but this is the first promising sign for significantly
cooler and wetter weather I have seen in quite sometime.

&&

.AVIATION...18Z TAFs...Southerly winds increased Tuesday afternoon.
Southerly winds at CEC through 2000 ft AGL up to 30 kts will
bring a low end threat for low level turbulence through 0Z
Wednesday. Light rainfall will continue spreading in with the
front, mostly over CEC. Light rainfall to light drizzle will also
impact KACV into Wednesday morning.

MFVR ceilings have a high probability of occurring at the coastal
terminals (60-70%) this afternoon and overnight. There is a lower
chance for IFR, but MOS and HREF do show higher chances for periods
of IFR CIGS. Have included PROB30 chance for IFR CIGS in 18Z TAFS.
Chances for IFR decrease after the front slowly passes by 12Z, but
there will be lingering chances for IFR with possible light drizzle
going into 15Z Wednesday.

&&

.MARINE...A quick round of increased southerly winds over the
northern waters will quickly ease into Tuesday evening. The quick
duration of these southerly winds will not allow for much short
period seas development.

Northerly winds will quickly build in behind the front Wednesday
morning as a strong area of high pressure strengthens in from the
west over the Pacific Northwest. Winds have trended slightly lower
for these northerly winds, but the strengthened pressure gradient
will generate some sustained gale strength winds, with gusts
currently forecast to reach over 40 kts starting Wednesday afternoon
in the southern waters. The northerlies will quickly expand
northward through Wednesday evening. Steep seas will reach 12 to 15
late Wednesday through late Thursday. Winds will begin to ease late
Thursday. Gale conditions are forecast to reach into the inner
zones, but the limited coverage and duration still warranted a
Hazardous Seas Warning due to the combination of gales gusts and
large, steep seas.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 5 PM PDT this afternoon for
     PZZ450-470.

     Hazardous Seas Watch from Wednesday evening through
     Thursday morning for PZZ450.

     Hazardous Seas Watch from Wednesday afternoon through
     Thursday morning for PZZ455.

     Gale Watch from Wednesday evening through late Thursday
     night for PZZ470.

     Gale Watch from Wednesday afternoon through late Thursday
     night 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