Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 222144

National Weather Service Eureka CA
244 PM PDT Mon Apr 22 2019

.SYNOPSIS...Warming temperatures can be expected across interior
areas for the remainder of the work week, with typically cool
conditions along the coast. Very little precipitation is
expected, with a few afternoon showers possible across far eastern
Trinity and northeastern Mendocino counties each afternoon from
Tuesday through Thursday.


.DISCUSSION...The stubborn marine stratus plaguing the
Humboldt and Del Norte county coastlines this morning is finally
burning off early this afternoon. While the persistence of these
clouds is impressive along the Humboldt coast, the remainder of
northwestern California is relatively cloud free. This will set
the stage for a very pleasant rest of the afternoon throughout the
region. A building ridge of high pressure aloft is causing
temperatures to warm well into the 70s to low 80s throughout most
interior river valleys this afternoon. Cooler high temperatures
can be expected closer to the coast. Temperatures will continue to
increase Tuesday and Wednesday as the upper level ridge slowly
moves across the region. Afternoon highs are expected to climb
well into the 80s throughout the interior lower elevations, which
is approximately 10 to 15 degrees above normal for mid to late

While most locations during this period will remain dry, model
guidance continues to indicate that a combination of strong
surface heating, marginal atmospheric moisture, and moderately steep
mid level lapse rates will bring moderate instability to interior
mountains late in the afternoon Tuesday and Wednesday. While forcing
will be weak it will be possible for a few weak and high-based
showers to develop across far eastern Trinity and northeastern
Mendocino Counties. This will only occur over the highest terrain.
On Thursday, a quickly passing shortwave trough may provide some
slightly increased forcing that could improve the chances for
convection, although the increasing westerly and southwesterly flow
may push the favored region for initiation farther east and out of
the CWA altogether.

Later in the week and into the weekend, the upper level ridge will
weaken and slide off to the east, resulting in a gradual cooling
trend. While low probabilities for showers will continue across
the interior mountains, most areas will remain dry through the end
of the week. A weak trough approaching from the northwest late in
the weekend will likely continue this cooling trend into early
next week.


.AVIATION...Coastal stratus near and N of Cape Mendocino surged N
overnight due to a short duration (~3 hour) flow reversal. As a
result, low ceilings and fog made their way into KCEC as well as
KACV. The fog bank has nearly dissipated as of this writing. A more
expansive low cloud deck is located well offshore, with the E edge
gradually moving SE.

Expect offshore low clouds to gradually spread toward the coast
overnight near and N of Cape Mendocino with low-level moisture
pooling against the coastal terrain by midnight. Patchy ground fog
is possible at KCEC and KACV prior to daybreak. VFR conditions are
anticipated once again at KUKI. Gusty NW to N winds will continue
into the early evening hours, but winds are expected to mostly
decouple later tonight. /SEC


.MARINE...Gusty NW to N winds will continue over the coastal waters
through much of the period. Periods of gusts near gale force are
expected over the S outer waters, but marginal and infrequent enough
to continue with a strongly worded Small Craft Advisory. Extended
the advisory in time for the S outer waters, and have hoisted a new
advisory for the N outer waters starting Tuesday morning and
continuing through Wednesday evening. The inner waters S of Cape
Mendocino will occasionally reach low end advisory criteria, but
there is enough uncertainty to leave that area out of the advisory
for now. Seas of at least 7 to 9 feet are expected to continue
through much of the period, with generally lower seas near the
coast. NW swell at periods from 10 to 13 seconds is forecast to
persist into the first half of the weekend. /SEC


NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory from 9 AM Tuesday to midnight PDT Wednesday
     night for PZZ470.

     Small Craft Advisory until 3 AM PDT Tuesday for PZZ455.

     Small Craft Advisory until midnight PDT Wednesday night for



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