Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 261045
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
345 AM PDT Fri May 26 2017

.SYNOPSIS...An upper-level trough passing by to our northeast
will keep temperatures a few degrees below seasonal values and
some increase in the coastal stratus extent through Saturday
morning. By Saturday ridging aloft begins builds across the
region through at least the first half of next week. This ridge
will also bring warmer temperatures to the region, especially
across the interior.

&&


.DISCUSSION... SHORT TERM... (Friday through Saturday)
Stratus coverage over both Humboldt and Mendocino Counties
remains widespread this morning in response to the deeper marine
layer. This is in response to the upper level trough passing by to
the Northeast of the forecast area. Clouds today will be slow to
clear out due to the deeper marine layer. Look for a repeat
performance of this weather tonight, as stratus will again build
inland through the some of the interior valleys and along the
coast. Here, these clouds will help insulate the ground, keeping
overnight temperatures a little warmer. Otherwise, look for
temperatures to start out in the 40s this morning, with the
colder readings found across the interior east of the coastal
stratus. Clouds will gradually burn off to the coast by late
morning/early afternoon.

Temperatures this afternoon will be similar to Thursday along the
coast. However, with a trough axis taking its time to cross the
forecast area, highs across the interior will be a little cooler.
More coastal/valley stratus looks to develop tonight, in the
typically prone areas. These generally coastal stratus clouds will
burn off earlier on Saturday as ridging in the wake of the exiting
trough suppresses the marine layer. Afternoon high temperatures
will also begin to rise as heights increase with the building
ridge.

LONG TERM...
(Sunday through Friday)

Increasing temperatures and mainly dry conditions will be the main
theme for the weekend. The aforementioned trough axis will exit the
area to our east, with ridging aloft building across the region
through the first half of Monday. Increasing heights and warming
temperatures will provide seasonably warm conditions along the
coast, while interior locations warm several degrees, with a few
spots climbing into the 90s by Sunday/Monday.

The forecast become a little more interesting for the latter half of
the weekend into early next week as well concerning convective
potential. The models continue to show precipitation developing
across the Yolla Bollys and near the Trinity Alps on Sunday and
Monday. They do show lifted indices dropping into the -3 to -6
range with MLCAPEs of 750 to 1500 J/kg. Even so, I`m having trouble
buying into this as ridging will be prevalent, with no upper level
support nearby. With that in mind, it does look like convective
temperatures will be approached, but again, confidence in this
occurring isn`t high enough to add into forecast on Sunday so
have dropped any mention of that for Sunday. Otherwise, have left
the forecast unchanged.

The tail end of a trough passing by to our north by mid weak may
increase rain chances for locations north of highway 299 if the
GFS solution verifies. Otherwise, the net effect from the trough
will be some cooling aloft, allowing afternoon highs to drop a few
degrees for the middle to end of the work week. /mkn

&&

.MARINE..A period of light winds is expected across all the coastal
waters beginning today as the upper level pattern weakens. A
lingering short period fresh swell will persist through the morning
hours today before subsiding in the afternoon. The short period swell
will continue to subside through Monday and the upcoming work week.
Favorable marine conditions are expected to persist through next
week as the winds and waves drop.

&&

.AVIATION...Marine influence continues to build along the near
coast in the form of a low stratus deck.  Coastal terminals can
expect mvfr conditions during the night and morning hours and
possible some brief periods of ifr before cigs rise in the late
morning hours and mixing begins in the early afternoon. This pattern
should continue for at least a few days. Interior sites should
remain vfr except the coastal valleys where some stratus may creep
in from the west and fill the valleys during the early morning
hours.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 11 AM PDT this morning for PZZ450-455-
     470-475.

&&

$$

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