Small Craft Advisory 101, NWS Eureka, CA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
307 PM PDT Mon Sep 30 2024

.SYNOPSIS...A dry, warming trend is expected through mid week, along
with hot interior temperatures. Breezy northwesterly winds along the
coast, ease overnight into Tuesday. Gusty offshore flow over the
interior ridges will last through Tuesday. Dry and above normal
temperatures are expected to persist through the forecast period.

&&

.DISCUSSION...This morning, general offshore flow aloft aided in
keeping coastal Northwest California clear of coastal stratus.
Ridging continues to build into the area as pressure heights
indicate a warming trend through Tuesday and Wednesday with a warm
deep- layer air-mass developing across the WRN CONUS. Model
guidance has been consistent supporting 850 mb temperatures of
25-28C or so over much of the interior. Interior heat will build
today and then peak on Tuesday over much of the area. High
temperatures in the hottest valleys are expected to range from 97-
110F degrees. The HeatRisk is forecast to be moderate over most
interior areas, but a major HeatRisk is expected to occur over
portions of interior Mendocino and Lake counties on Tuesday and
Wednesday. By Wednesday, Del Norte County and most of Humboldt
County will only have minor HeatRisk as temperatures trend down
and the warmer temperatures shift south. Most of Trinity County,
as well as Mendocino and Lake counties, will remain in the
moderate HeatRisk range on Wednesday, with some areas in the major
risk and even fewer of the hottest valleys with extreme HeatRisk.

The heat will have impacts on some individuals sensitive to heat,
especially those without effective cooling and/or adequate
hydration. A Heat Advisory is now in effect from 11AM Tuesday
through 11 PM PDT Wednesday for interior Mendocino and Lake
counties. Meanwhile, thermal troughing will shift offshore heading
into Tuesday, allowing for coastal areas to even heat up into the
70s, with adjacent coastal areas reaching the low 80's on Tuesday as
the usual afternoon onshore breezes are quelled.

Wednesday, the high pressure weakens and "flattens" as an upper
level trough moves across the Pacific Northwest. This will promote
high clouds streaming across the area. Temperatures are expected to
decrease a few degrees, although will remain similar to late Tuesday
across the interior valleys. Breezy to locally windy conditions are
expected every day through Thursday, with overnight offshore flow.

The ridge aloft will shift eastward late in the week, with an
upstream upper level trough approaching the area. Cluster analysis
lacks agreement with regards to timing and location of this trough.
Models continue to differ with the progression of this system.

&&

.AVIATION...Blue skies are covering the forecast area due to warm
offshore winds at the 925mb (2500ft AGL) level. VFR conditions
should prevail for the next 24 hours with gusty north winds at KCEC
and possibly even at KACV. These winds have the potential to bring
some sea spray into the terminal space, which could lead to some
hazy skies and reduced visibilities. Sounding data is also
supportive of the aforementioned wind shear (direction & speed
shifts between sfc & 2000ft AGL) at the coastal terminals today and
returning again tonight. KUKI is lighter winds and all terminals
have high confidence with remaining cloud free for the TAF period.

&&

.MARINE...Gale strength northerlies will subside today in the outer
waters to just barely below criteria. Hazardous sea conditions and
strong north winds will remain in the marine zones through the rest
of the week. Marine conditions will even increase in severity again
tomorrow night into Wednesday morning with Gale force winds
returning creating locally generated waves of 15ft@11s in the outer
waters. These waves are predicted to travel into the inner waters
and create conditions hazardous for small crafts, even with minimal
influence of wind within the inner waters. This weekend however, it
seems as though the winds will start to die down and the seas should
begin to calm. Long range cluster model guidance agreements supports
this evolution as well.

&&

.FIRE WEATHER...A Red Flag Warning is in effect for zones 203 (Upper
Smith) and 204 (Lower Middle Klamath) through 11AM Tuesday. Low
daytime humidity values from 10 to 25 percent are occurring across
the interior. A headline remains for zone 264 (Lake County, portion
of Lake/Napa/Sonoma RU ) due to elevated fire weather threats. Winds
are expected to diminish this afternoon, but gusty conditions will
remain over Del Norte and northeastern Humboldt into Tuesday
morning. A drier airmass with an offshore flow component, will
promote poor RH recovery values this morning, and poor recoveries
Tuesday and Wednesday morning. Hot temperatures from 95 to 110F
along with low humidity and breezy offshore flow, will promote
elevated to locally critical fire weather risks for zones 283
(Trinity), 276 (Interior Mendocino), 277 (Western Mendocino NF), and
264 (Lake County, portion of Lake/Napa/Sonoma RU) through
Thursday.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Red Flag Warning until 11 AM PDT Tuesday for CAZ203-204.

     Heat Advisory from 11 AM Tuesday to 8 PM PDT Wednesday for
     CAZ110-111-113>115.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 9 AM PDT Tuesday for PZZ450.

     Gale Warning until 9 PM PDT this evening for PZZ470.

     Hazardous Seas Warning from 9 PM this evening to 3 AM PDT
     Tuesday for PZZ470.

     Hazardous Seas Warning until 3 AM PDT Tuesday for PZZ475.

&&

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