067
FXUS66 KMFR 180531
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1031 PM PDT Mon Aug 17 2026

.KEY MESSAGES...

* Slight chance of a thunderstorm in easternmost Douglas and
  northernmost Klamath counties into this evening.

* Otherwise, mainly dry weather expected through Thursday with
  slightly above normal warmth and typical afternoon breezes.

* Low pressure moves northward offshore Friday with an associated
  upper trough swinging through Saturday. This brings a slight
  chance for showers and thunderstorms, gusty, mainly afternoon
  and evening winds along with a cooling trend.

* Dry, warm weather returns Sunday.

&&

.DISCUSSION...A weak upper air disturbance is passing through the
area today and this has resulted in quite a bit of cloud cover
over the forecast area. As a result, convective development has
been muted. Still, some instability exists out there this
afternoon, focused near the mountains (Cascades and Siskiyous). As
the higher clouds thin out, there could be some late
afternoon/evening cumulus development. There`s a low to slight
chance (5-15%) of thunderstorms with the best chance near/north
of Crater Lake in easternmost Douglas (east of Toketee) and
northernmost Klamath (Chemult) counties.

Upper ridging over the SW U.S. will amplify a bit through midweek
with broad upper troughing offshore consolidating into a closed
low. This will bring above normal warmth to most areas through
Thursday with highs mostly 85-95F, though peaking at 90-100F on
Thursday. Nightly stratus intrusions and morning fog along the
coast will keep it cooler there (highs in the 60s/low 70s).

The low offshore will get a kick north-northeastward Friday into
Saturday as it gets absorbed into the westerlies. Models have been
waffling back and forth with respect to thunderstorm chances in
our area as this low lifts northward - will it be close enough to
the coast so that forcing is better or far enough offshore that
most of the forcing stays offshore or to our north? There should
at least be some moisture and instability, so there`s a slight
chance of showers and thunderstorms Friday. In addition,
increasing pressure gradients should lead to enhanced
afternoon/evening breezes. Initially, humidity will be quite low
over the East Side and in NorCal. Gusty wind/low RH may overlap
Friday afternoon/evening resulting in elevated to near critical
fire weather concerns. The associated upper trough should swing
through on Saturday. By then, most of the moisture will lift to
the north (slight chance may linger across northern counties), but
gusty afternoon/evening breezes could persist. Either way, we
should see a cooling trend Fri/Sat compared to the mid week
warmth.

It should dry out and turn warmer again Sunday with the flow aloft
turning more into the south Monday into mid next week. This could
increase chances for t-storms again. -Spilde

&&

.AVIATION...18/06Z TAFs...LIFR conditions will continue along the
coast tonight and linger into the morning hours. Some clearing is
possible by the afternoon with lower ceilings lingering just
offshore. Otherwise, VFR is expected for inland areas through the
TAF period.

-Smith

&&

.MARINE...Updated 830 PM PDT Monday, August 17, 2026...Gusty north
winds and steep, hazardous seas, highest during the afternoons and
evenings are expected south of Cape Blanco through Wednesday
evening. Conditions are expected to improve late in the week. The
strongest winds are expected during Tuesday afternoon and evening.
Conditions are expected to improve late in the week. -Spilde

&&

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

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

&&

$$