708
FXUS66 KMFR 211130
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
430 AM PDT Mon Sep 21 2026

.KEY MESSAGES...

* Seasonable temperatures and dry conditions will prevail most of
  the upcoming week but temperatures trend below normal end of
  week

* Rain chances increase Thurs/Fri (20%-60%) with isolated
  thunderstorm possible (10%-20%)

&&

.DISCUSSION...

A closed low is passing south of the forecast area today. As we
reach peak heating today, there is a very small chance for some
cumulus buildups, and this means we have about a 5%-10% chance of
one or two becoming a shower/thunderstorm over northern California
where some lift will be possible. Most likely there wont be much
activity today, and it may end up being cumulus scattered across
the area. High clouds will likely limit destabilization as well,
so this is an extremely low chance for lightning today but worth
mentioning.

As the low exits to the east, we will experience mostly zonal
flow over the forecast area which will lead to generally quiet
weather with very little impacts/hazards for the following
couple days. That said, by Thursday the upper flow becomes more
southwesterly as a trough develops over the Pacific. Deterministic
models differ in the trough axis timing coming over the west
coast and the forecast area, so confidence is low for
timing/coverage of potential rain and isolated thunderstorms, but
generally looking at increasing chances for both starting Thursday
and continuing through Friday. Activity at this time appears to
stay mostly over westside areas. Currently, instability is very
meager, so not expecting much in the realm of thunderstorm
chances, but we could see light rainfall across westside areas.

Thereafter, temperatures drop as the trough pushes eastward. For
example, Medford may only reach the upper 60s for a high on Friday
with temperatures struggling to reach the lower 70s through the
weekend. In other words, expecting a cool down later in the week
to below normal temperatures in the wake of the upper trough
across the region.

&&

.AVIATION (12Z TAFs)...

Along and near the coast a marine layer has brought low ceilings
(IFR) which is impacting KOTH and will likely continue through the
remainder of the cycle with ceilings around 1000 ft. While close
to KRBG, current thinking is these low ceilings wont make it into
Roseburg albeit very close. This means inland TAF sites should
remain in VFR through this cycle with only high clouds expanding
across the area from the south where a low pressure system is
passing.

&&

.MARINE...Updated 330 AM PDT Monday, September 21, 2026...Gusty
north winds will maintain steep seas south of Cape Arago through
this evening with very steep seas over the inner and partial outer
waters south of Brookings starting this afternoon as winds
increase. Winds ease some on Tuesday and conditions will improve
north of Cape Blanco as seas become less steep and transition to
swell dominated. However, steep to very steep seas likely persist
south of Cape Blanco through Tuesday evening. Conditions gradually
improve Wednesday into Thursday.

&&

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

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

Hazardous Seas Warning from 2 PM this afternoon to 11 PM PDT
     Tuesday for PZZ356-376.

     Small Craft Advisory until 2 PM PDT this afternoon for PZZ350-
     370.

&&

$$