773
FXUS66 KMFR 171148
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
448 AM PDT Mon Aug 17 2026

.KEY MESSAGES...

* Seasonal warmth, dry weather, and afternoon breezes continue.

* Slight chances for afternoon and evening thunderstorms remain
  over easternmost Douglas/northernmost Klamath counties this
  afternoon and evening.

* Temperatures increase slightly toward midweek.

* A passing cutoff low may bring slight thunderstorm chances,
  increased winds, and cooler temperatures to end the week and
  into the weekend


&&

.DISCUSSION...With an upper trough over the Pacific and a ridge over
the southern United States, southwesterly flow persists over the
area. This pattern will keep generally seasonal temperatures in the
forecast across the area for much of the week ahead. Incoming air
following this flow looks to stay fairly dry, limiting chances for
precipitation. With passing shortwaves supporting breezy afternoons
in addition to ongoing warm and dry conditions, fire weather
concerns continue through the week ahead.

For this afternoon and evening, models are showing a little more
support for isolated thunderstorms over northernmost Klamath County.
SPC CAM paintballs are showing a few stray cells in the ensemble`s
latest run. GFS imagery shows a small band of monsoonal moisture
reaching westward from a larger plume, which could help fuel any
activity. A lingering cirrus layer may work against these chances,
as daytime heating would play a significant role in providing
instability for these thunderstorms and reducing that heating would
reduce already low chances for thunderstorms. Overall, thunderstorm
chances near the Douglas/Klamath border is about 5-10%, but the
slight trend upwards from past days is notable. Chances look to drop
beyond today as the broader moisture plume moves eastward.

Temperatures will fluctuate a little through the forecast period.
The ridge over the southern US nudges westward in the middle of the
week, adding a few degrees to forecast highs. Towards the end of the
week, a cutoff low at the base of the Pacific trough moves towards
the area. The effects of the low`s approach are trending down, as
its current path keeps it west then north of the area. With this
path, thunderstorm chances decrease but are not completely absent.
Winds into the Shasta Valley and east of the Cascades look to
increase, but currently look to stay below any Advisory levels.
This low would push the upper ridge back to the east, bringing
temperatures a few degrees below normal into the weekend. -TAD

&&

.AVIATION...17/12Z TAFs...IFR/LIFR levels are present along the
Oregon coast early this morning under marine stratus. This layer
may reach into the Umpqua Valley and bring a brief period of MVFR
ceilings, but this layer would likely last a few hours at most.
Coastal stratus looks to clear out briefly this afternoon before
returning in the evening.

Other areas look to remain at VFR levels under high clouds early in
the day then clear skies in the afternoon and evening. -TAD

&&

.MARINE...Updated 830 PM PDT Sunday, August 16, 2026...There will be
brief, slight improvement overnight. But, due to gusty north winds,
the Small Craft Advisory in effect for most of the area south of
Cape Blanco (excepting near shore south of Brookings) has been
extended to cover all of the southern waters Monday afternoon
through Wednesday evening. The strongest winds are expected during
Tuesday afternoon and evening. Conditions are expected to improve
late in the week.

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT
     Wednesday for PZZ356-376.

&&

$$

TAD/TAD/TAD