939
FXUS66 KEKA 212218
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
318 PM PDT Fri Jun 21 2024

.SYNOPSIS...Hot weather in the interior expected this weekend.
Dry weather and above normal temperatures in the interior expected
to continue early to mid next week. Cooler temperatures possible
late next week.

&&

.DISCUSSION...Visible satellite imagery showed extensive coastal
stratus north of Cape Mendocino again this afternoon. Stratus has
been persistent along the Mendocino coast too, south of Fort
Bragg. A couple of clear areas have been opening up in the lee of
Cape Blanco and in the lee of Cape Mendocino this afternoon again.
These clear slots may spread southward this evening and provide
clearer/sunnier skies, however confidence that will occur is not
high. Extensive low clouds offshore over the coastal waters and a
steady northerly influx of cool-damp marine air underneath a solid
inversion will result in more stratus generation this afternoon
and evening. Inland areas away from the shoreline have been clearing
out, but coastal areas have been socked in. Coastal forecast has
been based largely on observations, climatology and persistence.
It may take another day or two for the coastally trapped shallow
moisture to finally release after weak frontal passage on Sunday.

Interior temperatures are forecast to peak on Saturday; upper 90`s
to around 103F. Moderate heat risk is forecast for Trinity, Lake
and interior Mendocino counties on Saturday. This level of heat
affects most individuals sensitive to heat, especially those
without effective cooling and/or adequate hydration. The heat
risk is forecast to diminish on Sunday but it will still be quite
hot and toasty in the Trinty, Lake and interior of Mendocino;
upper 90s to around 100F. Above normal temperatures are forecast
to continue into early to mid next week. NBM has been trending
warmer, though the coverage of moderate heat risk diminishes.

Late week, NBM remains consistent with temperatures trending down
as another trough digs offshore over the NE Pacific and approaches
the west coast. Potential for rain or showers with this trough is
not zero, generally less than 10% for a few hundredths. NBM
probabilities for more meaningful rain, a tenth or more, is
minuscule; 5% or less near the Oregon border late in the week.
Potential for stronger west-northwest winds across the interior
will be a greater concern for fire weather with low min RH`s <30%.
NBM 24-hour probabilities for peak gusts >35 mph increase to 60%
or more mid to late next week. DB

&&

.AVIATION...Persistent coastal stratus has continued to engulf
the North Coast through this afternoon resulting in mostly IFR
conditions. However, afternoon Vis satellite verified several
minor eddys and breaks-in overcast (BINOVC) streaks parallel to
the immediate coast. Thus, small areas of partial clearing were in
affect by 2PM...especially over Humboldt Bay. Now the eddys near
CEC were the catalyst for several wind direction reversals...which
resulted in CEC maintaining IFR Cigs. Coastal stratus also
continued to pile up along the coast at ACV. Some breaks into late
afternoon and evening expected, otherwise continued stratus
overnight/morning. Inland areas will remain VFR or mostly SKC
except for a few CU that popped up over extreme SE Trinity county
and the Trinity Alps. /TA

&&

.MARINE...A summer-time northerly wind regime will persist across
the waters through the weekend into early next week. Strongest
winds are forecast to occur over the outer waters and nearshore
downwind of Cape Mendocino and perhaps near Pt St George.
Most notable expansion fan will initially develop south of Cape
Mendocino this evening and overnight. A low end gale warning is in
effect for gusts up to 40kt. Moreover, very steep waves are
projected to build to around 10 feet with periods from 7-9
seconds across the southern waters - mostly outside 10NM.

Surface pressure gradient will be disrupted on Saturday, mostly
north of Cape Mendo, and north winds may lay down slightly.
Hazardous seas are still expected with waves around 6-7 feet at 6-7
on Saturday north of Cape Mendocino across the outer waters.

Northerlies will then spike up again with low end gales in the
realm of possibilities for the remainder of the weekend (Saturday
night into Sunday night) mostly downwind of Cape Mendocino. A gale
warning for gust >33kt for southern outer waters may need to be
extended into Saturday night, based on the HREF probabilities of
80-100%. As mentioned above the dry front will through a wrench in
the gears as far as forecast confidence goes; the coverage for
gale gusts does not appear to be sufficient based on a gust factor
of 25%. The duration is much more difficult to pin down, but all
it takes is 2 hours. After frontal, passage gradients should
tighten with longer duration and greater coverage for gale gusts
for the later portion of the weekend downwind of Cape Mendocino.

National Blend of Models (NBM) indicates northerly winds
remaining sufficiently elevated to support at least small craft
advisory early next week, followed by steady decrease into mid
week. Granted winds around 20-25kt are forecast to persist in the
lee of Cape Mendocino. DB

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 9 AM PDT Saturday for PZZ450.

     Small Craft Advisory until 10 AM PDT Sunday for PZZ455.

     Small Craft Advisory until 6 PM PDT Saturday for PZZ470.

     Small Craft Advisory until 3 PM PDT this afternoon for
     PZZ475.

     Gale Warning until 9 AM PDT Saturday for PZZ475.

&&

$$

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