845
FXUS66 KEKA 190701
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1201 AM PDT Wed Aug 19 2026

.KEY MESSAGES...

* Thick smoke remains stuck around the Hoopa Valley stretching from
  as far north as to Orleans as far south as the middle Eel River
  Valley. Weak transport winds will keep smoke here through the week.

* Warm Interior temperatures will ease through the week with
  persistent marine influence along shore.

* Another trough is expected to bring below normal temperatures and
  a very slight potential for isolated thunderstorms Friday.

&&

.SYNOPSIS...Warm temperatures will ease through the week thanks to
increasing marine influence. Marine clouds will be persistent along
shore with some slightly better clearing chances late week.


&&

.DISCUSSION...High pressure will diminish as an elongated trough
will gradually approach shore through the end of the week. This will
help push marine influence further inland and weaken high pressure,
allowing interior highs to cool into the upper 80s by late in the
week. Increasing marine influence will most likely help strengthen
and deepen the marine layer along shore, a deeper and slightly more
unstable marine layer may allow for better scattering in the late
afternoons. Smoke has continued to sock in valleys around the MP18
fire in Hoopa with smoke spilling into the Trinity River Valley in
the afternoons with terrain winds. The trough will certainly bring a
string of high clouds across the area around Friday, helping
reinforce cooler temperatures. There is potential for very isolated,
weak thunderstorms along the trough Friday, but instability appears
lacking in all models. Although there will be gusty southerly winds
aloft, no model shows them mixing to the surface where weak north
and west winds will persist. Most long range models show high
pressure at least briefly rebuilding this weekend. /JHW


&&

.AVIATION...(06Z TAFs)...Coastal stratus will remain persistent
along the coast. LIFR conditions are expected to continue early this
morning and into the afternoon with a slim chance for
scattering/clearing for coastal terminals. Southerly winds are
expected early this morning along the immediate coast this morning,
with periods of light winds as well. VFR conditions with periodic
high clouds are anticipated for interior terminals.



&&

.MARINE...Fresh north winds gusting up to 28kts have persisted
across the outer waters with steep seas up to 10 feet. Winds have
been much calmer closer to shore, with gusts only around 12 kts with
some seas up to 5 feet pushing in from the outer waters. Some
stronger north winds will briefly push into the southern outer
waters early Wednesday, mostly downwind of Cape Mendocino. Beyond
short period seas, a very minor 2 foot, mid period southerly swell
is augmenting the sea state. North winds gradually ease through the
week with particularly calm conditions int he northern waters by
Friday. /JHW


&&

.FIRE WEATHER...Hot and dry weather will decrease through the rest
of the week. Thermal belt strength will peak Wednesday morning with
poor RH recovery as low as 30 percent along mid and upper slopes.
Winds remain weak and terrain driven. Conditions will generally ease
through the end of the week with increasing marine influence. Weak
transport wind will continue to allow smoke accumulation around the
MP18 fire in Hoop and up the Trinity River Valley, creating some
extra, localized moderation of conditions.

The greatest forecast challenge remains thunderstorm potential
around Friday. There is high ensemble confidence that a strong
stream of midlevel tropical moisture will push across the area from
the southwest early Friday morning and through the day. At the same
time, a strong southerly jet forming offshore and aligning with
topography could provide and lift and enhance instability to allow
for thunderstorms. Even with this dynamic forcing, however, no model
is consistently showing any amount of instability. Similar events
have generated high clouds and virga, but little to no lightning.
There remains a very slight (5%) chance of lightning in northern
Trinity and Humboldt Counties Friday morning and afternoon, but
coverage would be sporadic and very isolated. Any lightning that
does occur will be dry, increasing fire risk. This forecast could
quickly change if a source of instability materializes. /JHW


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 AM PDT Wednesday for PZZ455.

     Small Craft Advisory until 9 PM PDT Wednesday for PZZ470.

     Small Craft Advisory until 9 AM PDT Thursday for PZZ475.

&&

$$

NOTE: The full forecast discussion is now regularly issued between
10 am/pm and 1 pm/am. Additional updates will be issued as needed.

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For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png