741
FXUS66 KMFR 101808
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1108 AM PDT Mon Aug 10 2026

.KEY MESSAGES...

* An uneventful upper pattern will allow daytime highs to drop to
  seasonal levels, or even a couple degrees below. Coastal areas
  will see a pattern of marine stratus developing and clearing.
  Seasonable warm returns to end the week.

* Periods of smoke accumulation are expected for Klamath, Lake,
  and Modoc counties. Areas around Klamath Falls are likely to see
  overnight/early morning smoke accumulation.

* Dry and breezy conditions support ongoing elevated fire weather
  concerns through midweek. Cascades and east side thunderstorm
  chances to end the week are a part of those concerns as well,
  but those chances are trending downward.

&&

.DISCUSSION...Zonal flow aloft to start the week will allow daytime
temperatures to steadily decrease across northern California and
southern Oregon. In the middle of the week, past guidance had a
trough dropping the Pacific. Recent deterministic imagery has this
trough farther east, which would have it descend over the area.
While this would not have any significant impacts as far as active
weather, a few extra degrees of cooling would let midweek
temperatures dip just beneath seasonal norms. For daytime highs, the
coast looks to stay in the high 60s to low 70s. West side valleys
could dip into the high 80s and east side areas could be in the low
80s.  Onshore flow will support a continuing pattern of
evening/overnight marine stratus along parts of the coast,
with clearing in the late morning and afternoon. This could also
bring lower than expected temperatures along the coast if stratus
endures into the afternoon.

Atmospheric moisture is still minimal with this pattern, and
elevated afternoon breezes are possible as weak disturbances
follow the upper flow. With ongoing dry, breezy conditions,
elevated fire weather concerns continue. Please see the FIRE
WEATHER discussion below for more details.

With the flow pattern looking to stay from the west or southwest,
smoke accumulation concerns will continue for Klamath, Lake, and
Modoc counties. When winds ease overnight, smoke from the Wrights
Spring Fire can settle near the surface. This can bring poor air
quality in the early morning far parts of Klamath Falls and along
Highway 39/139 past Tulelake. Afternoon breezes look to push smoke
to the east, which can bring poor air quality downwind into Lake and
Modoc counties. For areas west of the Cascades, some lingering
decreased air quality is possible in valleys and sheltered areas as
afternoon breezes may not have fully mixed out past smoke.

That change in the trough`s position is affecting thunderstorm
chances towards the end of the week and into the weekend. With more
southwest flow in place, monsoonal moisture becomes mostly cut off
from the area. This keeps the highest chances of thunderstorm
activity to the southeast or east (Nevada, eastern Oregon). Some
slight chances for isolated activity do remain, with weak CAPE (100-
250 J/Kg) and a band of atmospheric moisture indicating possible
thunderstorms over western Siskiyou County, along the Cascades, and
over northern Klamath/Lake counties. Those slight chances are
highest (5-10%) in the afternoon and evening of Friday and Saturday.
Confidence in any specific outcome remains low, given the
variability in the upper level pattern. More generally, a few
degrees of warming may bring weekend temperatures back to seasonal
levels. -TAD


&&

.AVIATION...10/18Z TAFs...Smoke will be concentrated south and east
of the Wright`s Spring Wildfire, across southern portions of Klamath
and Lake counties, eastern Siskiyou County, and Modoc County. This
includes MVFR ceilings and visibility reductions at Klamath Falls
late this morning into early this afternoon with improvement to VFR
later this afternoon. Smoke is not expected to be as concentrated at
Lakeview and Alturas.

Other than the fickle finger of fog near the beaches at Brookings,
marine stratus is well offshore and VFR prevails. Strong, north wind
gusts up to 35 kt will occur along the coast, including at North
Bend, this afternoon and evening. Areas of IFR are likely north of
Cape Blanco later this evening into early Tuesday morning.

Otherwise, expect VFR conditions with locally breezy winds this
afternoon and evening (gusts of around 20 kt). -Spilde

&&

.MARINE...Updated 1100 AM PDT Monday, August 10, 2026...Gusty north
winds will continue through Wednesday evening, with gales and very
steep seas south of Port Orford and within 40 nm of shore.
Elsewhere, steep seas are expected. Winds will begin to ease
Thursday, and diminish more noticeably on Friday into the weekend.
But, steep seas are likely to linger into Friday.

&&

.FIRE WEATHER...Updated 200 PM PDT Monday, August 10, 2026...Main
message remains the same -- we expect dry conditions through
Wednesday, then slight chances of thunderstorms/lightning in NorCal
Thursday. These chances expand up the Cascades and over the East
Side Fri/Sat. Latest 12Z guidance has diminished the overall
risk/coverage area compared to yesterday, so confidence still
remains low, especially with the specifics of where activity will be
focused each day.

We`ll stay in a pattern of very warm, very dry, and breezy
conditions through Wednesday. This pattern includes overnight breezy
east to northeast winds at ridge tops of SW Oregon and NW California
(most notably the Coast Range and Kalmiopsis Wilderness) along with
poor to moderate RH recovery tonight/Tuesday morning, trending to
improved but still moderate recovery in subsequent mornings. A
channeling of winds down the Chetco could result in some
drier/warmer conditions along the SW Oregon coast as well (though
the marine influence has held so far at the beaches).

The trend through midweek will be to lower daytime MaxTs down by a
degree or two each day, and this should subsequently allow daytime
MinRHs to be slightly higher. Even so, it`ll be dry and unstable, so
any fires on the landscape will still have the ability to grow
significantly, especially during the peak burning periods during the
afternoons/evenings. Overnight RH recoveries haven`t been good the
last couple of nights, generally only in the 20-35% range for some
of the upper slopes and ridges. There should be slight nightly
improvement in recoveries from NW to SE through the period. Things
trend toward normal after Wednesday, but temperatures still probably
remain a few degrees above normal for most locations.

Models and ensemble guidance continue to show a weakness or upper
trough developing near the California coast Wed/Thu and also show an
increase in monsoonal moisture coming up from the south late week.
Models are a bit farther east with their depictions today, so this
would keep the flow more SW (as opposed to due S). As such, coverage
area and risk has diminished since yesterday. There`s about a 5-10%
probability of a thunderstorm extending into southeast Modoc County
on Wednesday afternoon, but 10-20% chance into NorCal Thursday
pm/eve with the best chance for isolated thunderstorms Fri/Sat from
NorCal up the Cascades and across portions of the East Side. Given
plenty of uncertainty in strength of forcing mechanisms, overall
instability and moisture advection, confidence is low in the
locations where activity will be focused. Keep checking back for
updates since any lightning brings with it the risk of new fire
starts. -Spilde

&&

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

PACIFIC COASTAL WATERS...Gale Warning until 11 PM PDT Wednesday for
     PZZ356-376.

Small Craft Advisory until 11 PM PDT Wednesday for PZZ350-356-
     370-376.

&&

$$

TAD/TAD/TAD