Wildfire in Oregon, September 1 to 2, 2021

Area Forecast Discussion
National Weather Service Medford OR
907 PM PDT Tue Aug 31 2021

.DISCUSSION...No change to the forecast this evening. As described
in previous AFD, an upper trough is in place over the Pacific
Northwest and will remain in place with somewhat cooler
temperatures (i.e. not scorching) through Thursday. Fairly strong
NW-SE pressure gradient over the area late this afternoon and
evening with Roseburg gusting out of the north to around 25 mph.
The gradient will slacken somewhat overnight but offshore winds on
the south coast terrain should get a little gusty with places like
Red Mound set to be gusting to 25 mph or so overnight. GOES West
showed late afternoon smoke was churning fairly well over the
Devil's Knob Complex and headed south toward Jackson County. Seems
like another fairly smokey morning is on tap tomorrow. Stavish

&&

.AVIATION...01/00Z TAFs...At the coast...expect VFR through the
TAF period. Inland...lower visibilities from the smoke will remain
the main aviation impact this evening into Wednesday. We'll see
smoke settle into the valleys this evening and tonight especially
for areas west of the Cascades and for areas in Klamath County. KMFR
is expected to see VFR this evening then MVFR returning overnight
into Wednesday morning. KLMT and terminals east of the Cascades
may see some improvement tonight with a return of smoke impacts by
tomorrow afternoon. Continued periods of MVFR visibilities are
expected through Wednesday, especially across eastern Douglas,
Jackson, Klamath, Siskiyou and Modoc Counties. Locally,
visibilities may drop down to IFR thresholds. -CC

&&

.MARINE...Updated 800 PM PDT Tuesday 31 August 2021...Very steep
seas and gale force winds remain within the waters through Thursday
morning. A thermal trough will strengthen in the afternoon and
evenings bringing gale force winds to locations roughly south of
Gold Beach and between 5 to 35 miles off shore. Outside of that
area, winds should be below gale force criteria through Thursday
morning. By Friday afternoon and evening, the thermal trough will
weaken and winds will quickly subside Friday into the weekend. Seas
will also be around 3 to 4 feet from Friday through Sunday as a low
moving through will disturbs the wind pattern. -Smith/CC

&&

.PREV DISCUSSION... /Issued 252 PM PDT Tue Aug 31 2021/ The upper
level trough over the Pacific Northwest today will elongate,
stretching from southwest to northeast over the next few days, but
remaining over the region until the end of the week. A shortwave
ridge will then pass overhead Friday into Saturday, followed by a
steadily building ridge into early next week. This means that the
cooler temperatures today (around 5 degrees below normal for this
time of year) will see a steady warming trend through the week,
reaching a relative peak of around 5 degrees above normal on
Friday as the first ridge arrives.

There is a chance that we could see the passage of a weak, dry
cold front late Saturday into early Sunday, and this could bring
temperatures down just slightly for the weekend, but given model
trends, this may just materialize as a stronger marine push rather
than a proper frontal passage. With the next, larger ridge
building in, temperatures will resume their climb, reaching well
above normal values by early next week. It is worth mentioning,
however, that several model suites depict an upper level trough or
closed low approaching the region from the southwest towards the
end of the forecast term. While confidence is low, the resulting
pattern could be one that produces at least a very slight chance
of precipitation, so we will be watching closely.

Otherwise, the ongoing issue will be the continuous smoke over
much of the forecast area. The thickness of smoke in any given
area will depend greatly on fire activity and firefighting
efforts, as well as day to day winds, but overall, not much
improvement is expected overall, although some locations west of
the Cascades in Oregon could see intermittent periods of
improvement. An Air Quality Alert from the state of Oregon remains
in effect, and can be found at PDXAQAMFR. -BPN

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...
CA...None.

Pacific Coastal Waters...Small Craft Advisory until 11 AM PDT Thursday
     for PZZ350-356-370-376.
     Gale Warning until 11 AM PDT Thursday for PZZ356-376.