Hazardous Seas Warning 28, NWS Eureka, CA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
315 PM PDT Sat Aug 19 2023

.SYNOPSIS...Interior temperatures will remain slightly above
normal through the weekend, then cool below normal early next
week. The threat of thunderstorms across mostly the interior will
persist today through Monday with some lingering activity Tuesday
afternoon over the interior mountains.

&&

.DISCUSSION...The persistent upper low off the central CA coast
continues to meander in the base of a larger scale trough that
extends S from British Columbia. However, the large upper high
over the Central Plains remains entrenched. The smoke from
wildfires will keep temperatures across Del Norte and extreme NE
Humboldt counties fairly cool. The rest of the interior has been
above normal. More cloud cover will knock temperatures down some
on Sunday, followed by greater cooling and below normal
temperatures early next week.

Scattered thunderstorms got an early start this afternoon across
inland areas, with some of the storms producing copious amounts of
rainfall and gusty winds. Storm motion has been quite slow thus
far, but it may pick up later in the afternoon with storms moving
NW-N.

The upper low will continue to tap into residual monsoonal moisture
from the S, as well as producing vorticity maxima that rotate
counter-clockwise around the broader circulation. This will
continue the threat of at least isolated afternoon and evening
thunderstorms on Sunday across mainly the interior and triggered
by daytime heat. There is a low potential for some nocturnal
storms late tonight into early Sunday morning for southern Lake
and southern Mendocino as the cut-off low edges closer to the area.
The exact coverage and timing storms will be complicated by
ongoing smoke in the area and model variability.

As we get into early next week, moisture from the remnants of
Tropical Cyclone Hilary is expected to spread N from S CA.
The bulk of the rain will be shunted east of our area. Thick
cloud cover may also inhibit the potential for storms and deep
convection in the interior. However, there will be greater
coverage of showers with embedded isolated thunderstorms, with
rainfall of one half inch to one inch possible over the SE portion
of the area. /SEC

&&

.AVIATION...Visibilities along the coast have improved into the
afternoon, while ceilings will most likely remain MVFR to IFR.
Current satellite and the HRRR smoke model indicate smoke aloft
along the coast from the fires in Del Norte, western Siskiyou, and
northern Humboldt counties which will continue to stream south along
the coast aiding in the broken to overcast skies at coastal
terminals north of Cape Mendocino. Marine stratus is expected to
take back over along the North Coast this evening and overnight
bringing visibilities and ceilings down to IFR/LIFR conditions at
coastal terminals. Isolated thunderstorms will continue to pop up in
the interior of the region, particularly eastern Humboldt, Trinity,
northeastern Mendocino, and extreme northern Lake counties. Storm
activity will diminish into the evening. VFR conditions with some
gusty southerly winds are expected at KUKI this afternoon and
evening with winds calming overnight.

&&

.MARINE...Seas will continue to diminish and by early this evening be
below hazardous sea criteria in the outer waters. Small craft wind
criteria is expected to continue in the outer waters through
tomorrow evening. Northerly winds will increase to widespread gale
force gusts, particularly in the outer waters and are forecast to
persist into early Monday afternoon. Gusts to 40 knots could occur
in the our waters with isolated gusts to 45 knots in the northern
outer waters. Seas are expected to pick back up with the gale force
winds.

&&

.FIRE WEATHER...The mid shift issued a red flag warning for
abundant lightning through 8 PM this evening for fire weather
zones 204, 211, 212, 277 and 283, and this appears to be on track.
Gusty and erratic outflow winds will fan existing fires. South-
southeasterly flow aloft will increase today compared to yesterday
and mean storm motion is expected to increase later in the day.
Winds for the remainder of the weekend will generally remain
diurnally driven under 10 mph, with stronger westerly breezes
expected over exposed ridges and in channeled terrain. Northerly
and easterly breezes with localized gusts to 25 mph over exposed
terrain are expected Sunday night.

Remnant moisture from Hurricane Hilary will spread northward late
Sunday into Monday. Expect scattered showers and isolated,
embedded thunderstorms Sunday night and Monday, with wetting
rain, mostly across the interior. /SEC

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...Red Flag Warning until 8 PM this evening
      for CAZ204-211-212-277-283.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 9 PM this evening for PZZ450.
     Gale Warning until 3 PM this afternoon for PZZ470.
     Hazardous Seas Warning until 9 PM this evening for PZZ470-475.

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