Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 271145
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
445 AM PDT Tue Jun 27 2017

.SYNOPSIS...A few thunderstorms are possible over the Trinity horn
late this afternoon and this evening. After that, the weather will
return to a more typical summer pattern of mostly dry conditions.
Warm temperatures will return to inland areas by Wednesday and
persist through the weekend. Marine stratus will continue along
the coast during the overnight hours through rest of this week.

&&

.SHORT TERM (today thru Thursday night)...Low clouds, along with
some patches of drizzle, continue to cover much of the coastal
waters and adjacent land areas. The marine layer is deep (at least
2000 feet deep). As a result, there are minimal visibility
reductions, but the clouds themselves have pushed well inland into
the higher elevations. The latest profiler info from ACV
indicates that the marine layer likely maxed out in depth several
hours ago and will decrease in depth as we go through the day. As
a result, the high resolution models are indicating more erosion
of coastal clouds through the day, with partly cloudy skies
possible during the afternoon even near the coast. However, models
also indicate a seabreeze developing, which would act to push
remaining coastal clouds back toward the coast later in the day.
Nighttime and morning coastal clouds will continue over the next
few days, but improvement should be noted by each afternoon.

Convection Monday afternoon fired well NE of the Trinity Horn
while convective inhibition (CIN) limited development closer to
the area. Models continue to indicate a vorticity maximum moving
from NW to SE toward the area this afternoon and evening on the
backside of a departing and filling trough. It still appears there
will be enough instability over W Siskiyou County to support at
least isolated thunderstorms, and storm motion should carry them
SE into E Trinity County. Have continued to include this in the
forecast. The timing for this activity appears to be either very
late this afternoon or early this evening.

Inland temperatures will be near normal today, then rise to about
10 degrees above normal by Wednesday as an upper ridge builds
back over the area. Present indications are that little in the way
of offshore flow will develop, which will keep coastal areas
seasonable. The weather will be mostly dry. /SEC

.LONG TERM (Friday thru Monday)...The longwave pattern holds
ridging over the western United States Friday and Saturday before a
broad trough shifts over the west on Sunday into early next week.
Thus expect mostly dry weather this weekend with inland temperatures
continuing to reach above normal values for this time of year. 500
mb heights will fall Friday and Saturday as a shortwave embedded in
the upper flow approaches the region from the northwest. Some
convective showers, possibly a thunderstorm, may be possible across
the interior Friday afternoon/evening as this shortwave slides over
the region. However, summertime thunderstorms tend to be more
conducive when shortwaves travel from the southwest, with
southeasterly winds helping to prime the environment for storm
development with moisture and instability. All in all, still not
confident enough to add storms to the forecast at this point in
time. Coastal temperatures will remain more seasonal with stratus
likely impacting parts of the northwest coast with scattering
afternoon skies. /KML.

&&

.AVIATION...The stratus deck early this morning wasn`t as expansive
as previous mornings with patchy cloud coverage along the NWCA
coast. The marine layer, however, remained deep as satellite imagery
showed stratus penetrated well inland once again last night. MVFR
ceilings this morning are expected to lift and scatter resulting in
predominately VFR conditions along the coast by the afternoon. MVFR
ceilings should return to the coast tonight with VFR expected to
prevail across most of the interior. /KML

&&

.MARINE...Surface high pressure has begun to build back towards
the California coastline. This tighter pressure gradient is
beginning to increase the northerly winds across the waters which
will in turn increase wave steepness later this afternoon.

A small craft advisory is currently set to take effect Tuesday
evening for the outer waters. This will have to be watched carefully
by the day shift as latest model trends have come in faster with the
small craft advisory winds. If observations show this speedier
solution the small craft advisory may go into effect this afternoon.
Some gale force gusts will be possible across the outer waters
starting Wednesday afternoon however with limited spatial coverage
and marginal strength no gale warning will be required (yet?).

The inner waters small craft advisory will take effect very early
Wednesday morning with the primary concern of large steep waves.
Winds should stay below small craft advisory except near Cape
Mendocino and Point St George where gustier winds are expected.

While the small craft advisories only go through early Friday
morning these may need to be extended.  For now will hold of on
extending the advisories until we get later into the week.  The
outer waters small craft advisory may need to get upgraded to a gale
warning Friday evening  as the southern outer waters could
experience some more widespread gale force gusts through the
weekend. The northern outer waters may also need a gale warning for
late in the weekend as well, as gale force gusts should increase in
spatial coverage.  Stay tuned for possible extensions or upgrades.
/WCI

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from 3 AM Wednesday to 3 AM Friday for
     PZZ450-455.
     Small Craft Advisory from 9 PM this evening to 3 AM Friday
     for PZZ470-475.

$$

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