Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 162244
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
344 PM PDT Tue Jul 16 2019

.SYNOPSIS...Aside from patchy drizzle, dry weather is expected
across northwest California through the weekend. Interior high
temperatures will generally be in the 80s to low 90s across the
interior, with hotter spots warming into the mid to upper 90s
Wednesday and Thursday. Abundant sunshine will occur across the
interior this week, while periods of marine stratus continue for
most coastal areas.

&&

.DISCUSSION...Definitely a noticeably cooler and cloudier
afternoon compared to yesterday for portions of the coast, and
especially some of the near-coastal river valleys of Humboldt and
Del Norte county. The cooling has come thanks to a deeper marine
layer and inland push of marine stratus, which has been slow to
retreat even this afternoon across northwestern Humboldt County.
This deeper marine push was a result of a passing mid/upper-level
trough, which also brought in some cooler air aloft. This air has
weakened the marine inversion enough to allow for some mixing and
partial clearing of the stratus and stratocumulus in some spots,
particularly around McKinleyville and Arcata. This trend may
continue for a little while longer into the early evening with
breezier north-northwest winds than the past few days. Otherwise,
expect the stratus will fill back in tonight. Stratus is already
expanding along the Mendocino coast between Fort Bragg and Point
Arena, which likely portends a cloudier overnight and morning
ahead for western Mendocino County. Wednesday afternoon may turn
out a bit sunnier for coastal areas than today, as the marine
cloudiness should be a bit shallower and thinner.

Disturbances will continue to occasionally swing through the
persistent Pacific Northwest trough through the end of the week.
One of these will clip northwest California Wednesday night into
Thursday. Model guidance supports the idea of a deepening marine
layer once again, with perhaps some drizzle and fog and a more
persistently cloudier day on Thursday.

Heading through the weekend and into next week, little change is
expected in the overall sensible weather across our region, with
continued dry weather outside of any drizzle at the coast. The
consensus of deterministic and long- range guidance points toward
a building high pressure ridge over the western United States,
while our longwave trough effectively retrogrades farther offshore
to our west. This may allow temperatures inland to creep above
seasonal averages, but even the hottest spots should not rise much
above the mid to upper 90s. The marine layer cloudiness may
become shallower, but also could tend to be more persistent at the
immediate coast. Northerly winds will probably tend to be lighter
after some breezier afternoons this week. /AAD

&&

.AVIATION...Stratus, fog, and even some patchy drizzle have lingered
along the Redwood coast throughout the day, with conditions at
coastal terminals fluctuating between LIFR and MVFR well into the
afternoon. Expect this trend to continue into the evening before
conditions slide back towards more solid LIFR overnight. Recent
visible satellite trends suggest CEC may see a few periods of VFR
this afternoon, however localized stratus development in the
vicinity of Pt Saint George is maintaining IFR cigs as the
prevailing condition for the time being. There is some reason for
optimism that we could see a bit more clearing at the coast on
Wednesday with the low level inversion looking a little weaker and
the marine layer trending a bit shallower, however confidence is on
the low side as the evolution of the marine layer has proven very
difficult to nail down in recent days. Meanwhile, VFR conditions are
expected for the remainder of the week for inland airfields
including UKI. /CB

&&

.MARINE...Northerly winds will continue to increase through this
evening before peaking overnight. Sustained wind speeds of 15 to 25
kt can be expected in many areas, with the strongest winds located
near and south of Cape Mendocino and in the vicinity of Point Saint
George where gusts to 30 kt can be expected. This will generate
larger, steep seas, generally ranging from 6 to 9 feet with a period
of 6 to 7 seconds. Winds will weaken approximately 5 kt or so
Wednesday through early Thursday, but seas will remain generally
elevated, particularly from Cape Mendocino southward.

By Thursday afternoon, winds will increase markedly across the
waters, and this will continue into the weekend. WInds will once
again be strongest across the outer waters and near/south of Cape
Mendocino, where sustained winds of 25 to 30 kt and gusts to 35 kt
will be possible. In the more sheltered areas along the Humboldt
coast, winds of 15 to 25 kt will be more common. In any case, this
will drive elevated and steep seas through the weekend.

In addition to the steep seas discussed above, a modest southerly
swell will continue to build into the waters through roughly
Thursday, with wave heights of around 3 to 4 feet and a period of
around 17 or 18 seconds. While not particularly large, its
presence may be felt in coves, harbor entrances and along beaches
with southerly exposure. Another small mid-period swell will enter
the waters from the northwest late Wednesday or early Thursday.
/BRC/CB

&&


.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory
     until noon PDT Wednesday for PZZ470.

     Small Craft Advisory until 3 AM PDT Thursday for PZZ455.

     Small Craft Advisory until 9 AM PDT Thursday for PZZ475.

&&

$$

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