Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 162227

National Weather Service Eureka CA
327 PM PDT Tue Aug 16 2022

.SYNOPSIS...An upper ridge positioned over the Western United
States will promote very hot afternoon temperatures across
interior portions of Northwest California through Thursday. In
addition, an upper disturbance entering Northern California during
Wednesday will aid in the development of isolated to scattered
thunderstorms. Otherwise, temperatures will gradually cool late in
the week as the previously mentioned ridge shifts east away from
the region.


.DISCUSSION...Main concerns with weather continue to center around
high afternoon temperatures associated with a bit of a heat wave
over the southern zones. Heat advisories continue as the
persistent upper-level ridge subtly amplifies over the WRN CONUS
during the next 12 hours. Some areas are seeing some relief from
the heat due to lingering smoke across the Trinity valleys but
enduring the temps and the some is not exactly pleasant either.
The smoke from the SRF Complex fires continues to plague much of
the valleys within the vicinity of the Trinity River drainage and
its tributaries but pictures from space today do show less smoke
than yesterday and a little less emanating from the fires
themselves. Air quality alerts are in place once again today to
address the hazardous breathing. Still on track for potential
thunderstorm development tomorrow. What was once considered a
feature to affect only Trinity county is now expanding both west
and southward as high res model guidance suggests additional
activity for Mendocino, Humboldt and Lake Counties. This is really
translating into more of a fire weather concern due to the
potential of new fire starts and inevitably more smoke. Recent
projected soundings suggest a scenario supporting high based
and/or elevated thunderstorm initiation over the interior
mountains of Trinity, far eastern Humboldt, and northeastern
Mendocino Counties during Wednesday afternoon. That activity then
spreads north within model solutions during the evening before
exiting across the Klamath mountains of Siskiyou and southwest
Oregon. POP values have been raised slightly due to increasing
confidence in storm development...and possible extending this
activity into Wednesday night. Thursday afternoon may also require
a mention of storms over the alps but any activity should be much
less in space and intensity than what may be observed Wednesday.
Thereafter, the WRN CONUS upper ridge is forecast to break
down/shift eastward during late week, while a weak trough moves
east across the NERN PAC. The trough is expected to be
insufficient for precipitation development, but interior
temperatures will likely cool back into the low to mid 90s in
response to falling heights aloft.


.AVIATION...Coastal stratus continued along much of the coast today. The result
has been LIFR/IFR conditions impacting ACV and CEC coastal
airports...especially before noonday. A mid morning pirep reported
Cigs OVC004 and tops at OVC010 further confirming observations. At
least partial clearing can be expected in mid-late afternoon...
therefore generally duplicating previous days. Stratus will
restrengthen in the evening. Inland conditions in the northern areas
could be significantly impacted by wildfire smoke. Some smoke aloft
drifted to the west-southwest, especially over Kneeland, Carlotta
and Fortuna. UKI will remain SKC/VFR.


.MARINE...Continued elevated marine conditions across all waters
as strong breezes to near gales are forecast to persist over the
outer waters through this evening. Gusts up to 40 kt will be
possible over the outer zones, particularly in the lee of Cape
Mendocino and Cape Blanco.  A gale warning will remain in effect
through this evening for the outer waters with steep, short-period
seas propagating toward the coast in response to the gusty winds.
Otherwise, a small, west southwesterly swell is forecast to move
through the coastal waters starting Wednesday. /EYS/jt


.FIRE WEATHER...Elevated fire weather conditions continue across
northwest CA with a combination of hot and dry conditions and
thunderstorm development. A Red Flag Warning is in effect to
reflect expected thundertorms development tomorrow beginning as
early as the late morning over the southern zones and spreading
north and northwestward throughout the day. Forecast models are
painting very little to no rain tomorrow mainly as a result very
dry lower layers of the airmass. In addition to the dryish nature
of the strikes latest high res guidance is expanding on this
coverage spatially off to the west. The next shifts may need to
nudge the current coverage a little more westward to include zone
276 the Mendocino Zone. In addition to the convective activity
and hot and dry conditions and related to the instability the
Mixing Heights are still forecast to exceed 10k feet with high
ventilation rate values as well. All of this may be subdued by
lingering smoke and a lack of sunshine...nonetheless the
ingredients are there. After Thursday, temperatures are forecast
to gradually cool through the weekend as an upper trough becomes
positioned over the Northeastern Pacific.



     Red Flag Warning from 11 AM to 11 PM PDT Wednesday for

     Heat Advisory until 8 PM PDT Wednesday for CAZ108-110-111-

     Small Craft Advisory until 9 AM PDT Wednesday for PZZ450-

     Gale Warning until midnight PDT tonight for PZZ470.

     Gale Warning until 9 PM PDT this evening for PZZ475.



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