Area Forecast Discussion
Issued by NWS Eureka, CA

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634
FXUS66 KEKA 272258
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
358 PM PDT Tue Jun 27 2017

.SYNOPSIS...
A few thunderstorms are possible over the Trinity horn late this
through 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.

&&

.DISCUSSION...
(Tonight thru Thursday night)

Low stratus has been rather stubborn along most of the Redwood
Coast this afternoon, with the latest visible imagery loop
showing it already starting it`s inward building. Aside from that,
convection has struggled to develop this afternoon across the
Trinity Horn. This is likely due to meager instability, with the
latest SPC mesoanalysis showing MLCAPEs running in the 100-250
J/kg range. However, with a few hours of the diurnal heating left,
and the cumulus field continuing to slowly build, we left the
slight chance of thunder in the forecast for the northern Trinity
zone. Otherwise, look for a continued push down the river
valleys/along the coast, with a repeat scenario expected as to
what we seen last night/early this morning. Temperatures will be
near seasonal values overnight.

For your Thursday, the latest guidance indicates a somewhat
better eroding of the cloud stratus for the afternoon, so will opt
for the more optimistic forecast. Heights aloft will increase
somewhat, allowing afternoon interior temperatures to increase a
few degrees. /PD

.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...
Todays`s marine layer was fairly uniformed and extensive (although
a little less than yesterday)across The North Coast with clouds
seeping into EEL River valleys. Pilot reports from ACV & CEC showed
the cigs to range from around 015-030 feet. Visibilities generally
remained VFR across the region.  By 2:00 PM, low clouds remained
entrenched across the Humboldt Coast with cigs mostly unvarying in
bases...while some clearing was occurring at CEC. In Mendocino, the
stratus was not as prevalent as in the northern areas, and although
UKI reported clear skies overnight, satellite imagery and web cam
pictures actually showed areas of marines clouds having split
into the coastal mountain valleys...especially north of UKI. Model
guidance indicated that stratus and fog will once again dominate
the coast overnight and return to the local river valleys.
However, expect that UKI will remain mostly clear - sct with the
possibility of some morsels of clouds tipping the coastal range
into parts of Mendocino. /TA


&&

.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 allow the wave heights to continue to increase
through the next 24 hours.

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 was issued as of
right now.

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.
Additional headlines may be issued or extended for the end of the
week/into the weekend. /WCI/PD

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory from 3 AM Wednesday to 3 AM PDT Friday for
     PZZ450-455.

     Small Craft Advisory from 9 PM this evening to 3 AM PDT Friday
     for PZZ470-475.

&&

$$

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