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Area forecast discussion 
National Weather Service Eureka California
916 PM PDT Friday Jul 29 2016

Update...
sent out a quick update to the marine and coastal zones to add
patchy drizzle to the forecast. /Pd

&&

Previous discussion... /issued 400 PM PDT Friday Jul 29 2016/

Synopsis...hot and dry conditions will continue tomorrow, and a
slight cooling trend can be expected through early next week. A
shallow marine layer will persist along the coast, with nocturnal
fog and stratus and mild temperatures.

Discussion...very few changes were made to this iteration of the
forecast, as modest heat relief later in the weekend and early
next week appears to be on track. Temperatures this afternoon
once again soared well into the triple digits across our low
interior valleys, even approaching 110 in a few spots. Meanwhile,
a shallow marine layer continues to hold firm along the immediate
coastal plain, resulting in an extremely sharp temperature
gradient of 30 to 40 degrees over a distance of approximately 20
miles in some cases. While tomorrow's weather will be similar to
today in many aspects, a slight cooling trend will begin as a weak
upper level trough begins to move inland. This won't be
particularly noticeable tomorrow as highs will only be
approximately 5 degrees cooler, but this gradual downward trend
will continue through early next week when interior temperatures
will settle to around 85 to 95 degrees as opposed to the
widespread 100-110 we've seen the past few days. Unfortunately
though, by the middle and end of next week a building upper level
ridge will likely cause temperatures to increase back into the
upper 90s and low 100s. Meanwhile, very little change can be
expected with the marine layer along the coast, aside from a
slight deepening late in the weekend and early next week as the
upper trough passes by. Expect continued nocturnal shallow
stratus and fog in these coastal areas.

As for convection this afternoon, a very subtle upper disturbance
just offshore continues to slowly move towards the coast, but does
not appear to be providing a great deal of additional lift. While
widespread thunderstorms have developed east of the Sierra crest
this afternoon, thus far only a small field of agitated cumulus
clouds have developed in our region near the tip of the Trinity
horn and south-central Siskiyou County. While chances of anything
substantial developing from this activity is very slim, it would
not be impossible to see a brief thunderstorm emerge from this
activity later this afternoon and evening. This will likely only
have implications for firefighters and outdoor enthusiasts, and
more on this potential is discussed in the fire weather section
below. /Brc

Aviation...terrain induced subsidence from strong northerly flow
helped clear out the coast north of Cape Mendocino this afternoon
while extensive marine stratus has impacted most of the rest of
the California coast today. VFR should prevail on the north coast
before stratus makes a comeback around Humboldt Bay this evening.
This should afflict kacv but easterly winds over del Norte County
should help keep kcec clearer with better visibility and
definitely less cloud cover. I wouldn't be surprised, however, if
south winds along the coast ushered in some lower ceilings from
the south early Saturday morning. The marine layer should deepen
slightly tonight as an upper wave allows 500mb heights to fall.
This will allow stratus to penetrate slightly father inland than
it did last night. Expect IFR conditions along the coast tonight
with mostly VFR across the interior. /Kml

Marine...very little meaningful change can be expected throughout
the waters for the foreseeable future, as strong northerly winds
with gale force gusts are expected to persist with only minor
fluctuations. While nearshore buoys are not measuring much in the
way of strong winds, this is due to the presence of a persistent
southerly flow reversal along much of the coast, keeping these
near shore areas a bit sheltered from the building gales farther
offshore. However, a steep fresh swell of around 9 to 11 feet at
10 seconds is still managing to propagate into the near shore
waters north of Cape Mendocino, resulting in rough seas
regardless of the relatively weaker winds.

Through the remainder of the evening and overnight, winds will
continue to gradually increase across the offshore waters,
particularly across the waters north of Cape Mendocino, where
conditions are expected to be noticeably worse than the waters
farther south. Winds and seas will peak overnight tonight, and
remain more or less steady-state through Sunday. A passing trough
of low pressure may help to reduce winds by approximately 5 to 10
kt Monday and Tuesday, but winds are expected to increase yet
again by the middle of the week. In any case, this will not offer
much relief, and conditions are expected to remain hazardous
almost continuously through the next 7 days. /Brc

Fire weather...hot and dry conditions are expected to continue
through tomorrow, with only a modest cool-down expected late in
the weekend through early next week. Gusty offshore winds were
observed once again across the high coastal peaks of del norte and
northern Humboldt counties last night, with moderate to poor
humidity recoveries as well. Expect similar conditions overnight
tonight, although recoveries and winds will likely not be severe
enough to require a headline. Afternoon temperatures will
gradually fall by about 5 to 10 degrees over the next two days,
and generally hold steady through early next week, offering some
very modest relief.

Meanwhile, prospects for lightning are waning but not completely
impossible across the northernmost mountains of Trinity County
later this afternoon and evening. A fairly substantial cumulus
field has build near the Scott mountains and Russian Wilderness
areas, and it would not be completely out of the question to see a
brief shower or thunderstorm develop out of this activity.
However, any showers will likely be very isolated and short lived,
and a red flag warning does not appear to be warranted at this
time. Still, given the dryness of fuels in the region, it bears
watching through the remainder of the evening.

&&

Eka watches/warnings/advisories...
California...none.
Northwest California coastal waters...Small Craft Advisory until 11 am PDT Monday for pzz450.

Gale Warning until 8 am PDT Monday for pzz470.

Small Craft Advisory until 5 am PDT Wednesday for pzz475.

&&

$$

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