960
FXUS66 KMFR 191133
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
433 AM PDT Sat Sep 19 2026

.KEY MESSAGES...

* Low impact weather expected this weekend and through at least
  Thursday. Inland temperatures will generally be a few to several
  degrees above normal (though as much as a dozen degrees), with
  late day breezes at or slightly below typical strength.

* Also, coastal stratus and patchy fog mainly during the night and
  morning hours, extending into the central portion of the Umpqua
  Valley in the early mornings.

* A frontal passage is possible late in the week. It would at
  least bring stronger breezes to the east side, but could be
  strong enough to bring shower and thunderstorm chances to
  southern Oregon and northern California.

&&

.DISCUSSION....A ridge will build across the area this weekend.
This is producing night and morning valley inversions with marine
stratus extending into coastal valleys. These low clouds will be
stubborn to clear at the coast, especially during Sunday. But,
will gradually dissipate in the Umpqua Valley by the afternoon,
and also be slowest to develop in the overnight hours in the
Roseburg area.

Besides the stratus, there will be variable amounts of mainly thin
high clouds over the area. This is the result of a change to a
seasonable pattern of westerly flow aloft while a series of
disturbances track into western Canada. The main characteristic
through much of next week will be dry and warm to very warm
weather.

There will be a bit of a change on Wednesday as a slightly
stronger front brings rain chances farther south...into western
Washington. For our area, that is expected to result in a thicker
band of high clouds, a few degrees of cooling, and a modest
uptick in the strength of afternoon east side breezes.

East side winds will see a more noticeable uptick, though likely
still just breezy, on Thursday and/or Friday as a broader trough
over the eastern Pacific Ocean swings southeastward. Forecast
uncertainty increases substantially beginning Friday. For late in
the week, the 00Z operational versions of the ECMWF and GFS are
both on the stronger side of their respective suites of ensemble
data. This situation is well represented by the NBM with its
probabilities of precipitation forecast at less than 10%. With
that said, around 20% of GEFS members and around 30% of ECMWF
members indicate a frontal passage either on Friday or during next
weekend that would be strong enough to warrant mentionable shower
chances in our area, stronger breezes, and cooling of
temperatures to at least near normal levels. Lastly, of that
cohort of active solutions, a few also depict an environment that
would support a modest level of thunderstorm development.

&&

.MARINE...Updated 100 AM PDT Saturday, September 19, 2026...Light
northerly winds and low seas will be at a minimum early this
morning. North winds begin to increase today with steep seas
developing south of Cape Blanco late this evening, then likely
extending to Cape Arago during Sunday afternoon and evening. North
winds and wind driven seas are likely to continue building to a peak
Monday evening, with very steep seas and gale force gusts possible
south of Gold Beach. Conditions remain near that level on Tuesday
with at least brief, further slight improvement on Wednesday.


&&

.AVIATION...19/12Z TAFs...Marine low clouds and fog extending into
the coastal valleys and Umpqua Valley will be the only impact to
aviation through Sunday morning. A mix of IFR and MVFR low clouds is
the predominant condition, with patchy fog. MVFR stratus is expected
to extend from the lower Umpqua Valley into most of the remainder of
the Umpqua Valley, including Roseburg/KRBG, from around 13Z through
17Z this morning. Gradual improvement is expected from mid-morning
through the afternoon, though with areas of mainly MVFR ceilings
persisting at the coast through the day. A similar mix of IFR and
MVFR is expected to return to the same areas early this evening into
Sunday morning.

Other inland areas will remain at VFR levels under clear skies
through Sunday morning, with weaker than normal diurnal breezes.

&&

.MARINE...Updated 100 AM PDT Saturday, September 19, 2026...Light
northerly winds and low seas will be at a minimum early this
morning. North winds begin to increase today with steep seas
developing south of Cape Blanco late this evening, then likely
extending to Cape Arago during Sunday afternoon and evening. North
winds and wind driven seas are likely to continue building to a peak
Monday evening, with very steep seas and gale force gusts possible
south of Gold Beach. Conditions remain near that level on Tuesday
with at least brief, further slight improvement on Wednesday.

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory from 11 PM this evening
     to 11 PM PDT Monday for PZZ356-376.

Hazardous Seas Watch from Monday afternoon through Monday
     evening for PZZ356-376.

     Small Craft Advisory from 2 PM Sunday to 11 PM PDT Monday for
     PZZ350-370.

&&

$$