Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 241159

National Weather Service Eureka CA
459 AM PDT Sat Jun 24 2017

.SYNOPSIS...Hot conditions will continue through today, with
gradual cooling to near normal temperatures beginning Sunday.
Isolated thunderstorms will be possible Sunday and Monday across
the interior. A few thunderstorms are also possible late this
afternoon and this evening over the Yolla Bollys.


.DISCUSSION...Early morning GOES-16 imagery from space shows that
the southerly surge of stratus and fog has made it N to the S OR
coastal waters. The RAP model once again has a good handle on the
clouds. Clouds have not made much inroads inland across the N
portion of the area overnight with only in and out ceilings along
the immediate coast. This is likely due to the lack of low-level
wind flow and subsidence at cloud level. Clouds do extend farther
inland over Humboldt Bay and up the Eel river valley to near Rio
Dell. In addition, low clouds extend inland over portions of
Mendocino county from Fort Bragg to near Navarro. Continued light
flow and inland heating should keep coastal areas partly cloudy,
with occasional periods of mostly cloudy skies around Humboldt Bay
and at the immediate coast. Clouds may push inland late this
afternoon as light flow becomes more onshore, but uncertainty is
high. Nighttime and morning coastal clouds will become more
prevalent over the next few days, but improvement should be noted
by each afternoon. As coastal clouds increase, there is the
potential for some patchy drizzle along the Redwood Coast,
particularly Sunday and Monday mornings. Hot inland temperatures
will continue through today, and the Heat Advisory will continue
through this evening.

Increased moisture and instability may lead to isolated
thunderstorms over the interior through Monday. Any thunderstorms
that develop today will likely wait until late afternoon or early
evening as moisture gradually increases from the S. Any storms
will likely be tied to ridgetops as these locations will aid
development through a layer of convective inhibition. More
moisture will be in place by Sunday, and there will be a vorticity
maximum rotating N across the area on the periphery of an E
Pacific upper low during maximum daytime heating. Have included
low end chance thunderstorms for N Trinity County with isolated
thunder possible over the remainder of Trinity as well as E Del
Norte and NE Humboldt counties. The chances for thunderstorms will
be waning on Monday as the upper low moves NE. However, may see
some isolated activity over the Trinity horn. See fire weather
section below for more information.

Less inland heat is expected early next week, but temperatures
will rise once again by mid-week to about 10 degrees above
normal. /SEC


.FIRE WEATHER...As mentioned above, the chances of thunderstorms
will be increasing a bit over the next couple of days. Some of
these storms may be dry in nature, especially late this afternoon.
For storms that do produce rain that reaches the ground, the slow
storm motion should allow the ground to get wet. As mentioned in
yesterday afternoon`s discussion, fuels in the higher elevations
remain fairly wet. Driest fuels are found across inland Mendocino
County. It appears most of the thunderstorm activity over the next
few days will favor locations N of zones 276 and 277. Will
continue to include headlines in the appropriate fire weather
zones. /SEC


.AVIATION...A dense stratus deck has inundated most of the
California coast as of early this morning and continues to surge
northward into the Oregon coastal waters. Although ceilings and
visibility had deteriorated along the Mendocino coast and Humboldt
Bay area, the stratus remained stationed offshore from KACV up
through the Del Norte coast. Conditions may bounce around between
VFR and IFR this morning at KACV and KCEC. Then low level subsidence
along the north coast coast should help peel the stratus away from
the coast. This is a very peculiar weather situation. Models and
guidance do not have a good handle on this pattern and so confidence
is not high. However, clouds are expected fill in along most of the
northwest California coast and penetrate the coastal valleys later
this evening. These areas should expect IFR to LIFR tonight with
primarily VFR across interior California. /KML


.MARINE...Light winds will persist through this weekend allowing
seas to remain low with no headlines required. This low sea state
will not last long as the pressure gradient begins to strengthen
across the waters on Tuesday. This strong pressure gradient will
usher in much stronger northerly winds and the seas will begin to
build in response to those winds. Large steep waves and gale force
wind gusts will be possible through at least next weekend. /WCI


CA...Heat Advisory until 8 PM this evening for CAZ102-105>108-110-



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