Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 250012

National Weather Service Eureka CA
512 PM PDT Wed May 24 2017

.SYNOPSIS...A broad upper level trough will bring near to below
normal high temperatures through the rest of this week. A gradual
warm up is expected for the weekend into early next week. Coastal
areas will continue to see night and morning fog and low clouds
with afternoon sunshine.


.UPDATE...An upper level trough moving into the Pacific Northwest
and northern rockies is bringing gusty northerly winds to the
coastal areas of northern CA. The strongest gusts are around the
Crescent city area where gusts to 47 mph have been reported. These
are expected to continue over the next several hours as before
winds diminish later tonight. These are slightly stronger than
previously expected so have issued a wind advisory for the Del
Norte county coast and updated the forecast. MKK/RCL


.PREV DISCUSSION... /issued 257 PM PDT Wed May 24 2017/

SYNOPSIS...A broad upper level trough will bring near to below
normal high temperatures through the rest of this week. A gradual
warm up is expected for the weekend into early next week. Coastal
areas will continue to see night and morning fog and low clouds
with afternoon sunshine.

DISCUSSION...High temperatures across the interior have been
running 5 to 15 degrees lower today compared to yesterday. The
cooling trend will continue on Thursday as a broad and baggy
upper trough from the northwest slides down an upper ridge over
the NE Pacific and tracks eastward. The trough aloft will slowly
edge eastward on Friday, however high temperatures inland may have
to wait until this weekend before recovering to normal levels.
Ridging aloft will build this weekend into the early portion of
next week and temperatures will increase above normal again.

The marine layer will keep temperatures more seasonal through the
week with morning cloudiness and afternoon sunshine for coastal
regions. The layer did deepen today and skies were slower to
clear around the Eureka area. South of the Cape, the Mendocino
coast has been socked in the last several days with the broken to
overcast clouds and fog. It has been much harder for the stratus
to clear out along the Mendo coast where several small scale
eddies have been spinning up every day. Confidence is not high
there will much if any change on Thursday. The slight increase in
northerly winds on Friday along with cooling aloft may force the
stratus back south into Central California.

An upper level ridge will amplify again this weekend bringing a
gradual warmup and above normal temperatures early next week. The
models continue to bring a splitting upper trough toward the coast
early next week. The end result appears to be a cut-off low that
will spiral southward along the central California coast by mid
week. There does appear to be some return flow or wrap around
moisture, however it remains too elusive at this time to pin-point
any particular day for tstms Mon-Wed next week.

AVIATION...Another day of low clouds and visibilities (LIFR-IFR)
at the coastal terminals extending from Mendocino-Del Norte. From
Cape Mendocino to Trinidad, the marine layer was especially
pronounced as it stretched over the Coastal Hills. CEC cleared by
late morning as strong northerly winds kicked in, but ACV was
still "socked in" at 2 PM. Mid-late afternoon will see mostly
sunny skies. However, lingering stratus will maintain over a few
local coastal spots. Late afternoon to evening clearing at much of
the coast before another layer of marine clouds return tonight.
Bases of the cloud CIGS are expected to be a little higher. Inland
areas will continue to be VFR sunny. For UKI, a southerly push
brought stratus up the Russian river and briefly into the UKI
valley in the morning. Models suggest a similar scenario for
Thursday morning.

MARINE...N winds will continue to increase thru this evening as the
gradient between high pressure over the E Pacific and an inverted
inland trough tightens. Strong gales will develop over the N outer
waters today with occasional gusts to storm force. Gale force gusts
will also develop over a large portion of the N near shore zone.
Across the S outer waters, sustained winds will reach gale force in
the NW corner of the zone, but frequent gale force gusts should
eventually develop elsewhere in the zone.

Model data continues to indicate that the pressure pattern and
associated gradient will spare the S near shore waters headline
criteria winds or seas. However, winds and seas will be more
treacherous near Cape Mendocino, and this area has been highlighted
in the text of the Coastal Waters Forecast. There is uncertainty as
to whether the short period N wind waves generated will be able to
affect enough of this zone to warrant an advisory for seas at some
point. Headlines are basically unchanged from the previous package.
Winds will begin to decrease late tonight and Thursday with lighter
winds returning for the weekend. /SEC

Mariners headed north should wait until Fri or Sat before resuming
travel. Seas will probably be too large and steep on Thursday. It
will still be choppy on Friday, however the trend is for northerly
winds and seas to subside north of Pt St George Fri through Sat.


CA...Wind Advisory until 9 PM PDT this evening for CAZ101.

NORTHWEST CALIFORNIA COASTAL WATERS...Gale Warning until 3 AM PDT Thursday for PZZ450.

     Gale Warning until 6 PM PDT Thursday for PZZ470.

     Gale Warning until noon PDT Thursday for PZZ475.



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