908
FXUS66 KMFR 132307
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
407 PM PDT Sun Sep 13 2026

...Updated Aviation Discussion...

.KEY MESSAGES...

* Showers will diminish by this evening with areas of frost
  developing overnight east of the Cascades.

* Temperatures trend warmer into the week with highs near normal.

* An upper low will bring a chance of showers and perhaps
  thunderstorms Tuesday and Wednesday.

* Temperatures trend warmer by Friday.

&&

.DISCUSSION...

A cool unstable airmass remains overhead with scattered showers
north of the Oregon and California border this afternoon. We`ll
see this cool showery weather continue until the later afternoon
and perhaps early evening. Eventually, the axis of this 500 mb low
will move eastwards and we`ll see high pressure begin to build
with deeper cool northwest flow continuing overnight. We could see
pockets of fog along the coast and some valleys Monday morning.
Dewpoints are not that high as of now and in the mid 40`s here in
Medford with mid 50`s along the coast. In any case, its something
to watch for.

Tuesday will trend warmer with more clearing and a high September
sun angle. We`re forecasting a high of 82 degrees here in Medford,
which is slightly cooler than our normal of 86 for this time of
year. Quiet fall like weather continues through Tuesday morning
before the short wave approaches the Pacific Northwest Tuesday
evening. There is a low chance of showers east of the Cascades on
Tuesday afternoon and evening.

By Wednesday, the NBM has a 15% chance of showers along the
Oregon and California border in the afternoon. The probability of
cloud to ground lightning is also increasing to about 15% over
most of our forecast area with lower probabilities along the coast
and west of the Cascades. Overall, it makes sense we see a few
weak thunderstorms develop Wednesday afternoon with enough
clearing. The GFS forecast soundings look good with enough CAPE
making it into the -10 to -20C layer.

The short wave will have a chance of becoming a cutoff low by
Thursday afternoon. Ensembles are not in great agreement of where
to exactly place this cutoff low with some GEFS members putting
it over northern Nevada while others keep it right over SW Oregon.
Looking at the latest QPF fields from the 12Z ECMWF ensemble, its
looking like showers will be around, it`s just a question of how
far west they`ll be. South central and south eastern Oregon will
likely see showers on Thursday afternoon. The NBM has a rough
10-15% chance of precipitation mainly east of the Cascades with
lower probabilities to the west.

By Friday, this low will likely be on the move to the the east
with 1/30 GEFS members keeping the low over us and about 6/50
12Z ECMWF ensemble members keeping showers over southern Oregon.
The latest NDFD PoP forecast is likely too dry and the chance of
precipitation should be increasing. Friday will also be one of the
warmer days next week with highs back into the lower 90`s here in
Medford.

Overall, most of the week will be dictated by where this upper
level low ends up. It could be a partly cloud showery type pattern
or trending even warmer and drier. No major weather impacts
anticipated this week.

-Smith

&&

.AVIATION...14/00Z TAFs...VFR levels continue across northern
California and southern Oregon  this afternoon, with  scattered to
broken mid level clouds inland across southwest Oregon and partial
mountain obscurations. Clouds will gradually clear this evening.
Then, areas of IFR/LIFR will develop along the coast, including at
North Bend (OTH) around 02-05Z and persist through late Monday
morning. Inland, areas of IFR/LIFR are expected to develop early
Monday morning in the Umpqua Basin, including at Roseburg (RBG).
Elsewhere, expect continued VFR.

&&

.MARINE...Updated 1000 AM PDT Sunday, September 13, 2026...Light
winds and seas today, becoming north winds tonight. Then, gusty
north winds develop Monday afternoon with steep seas south of Cape
Blanco. These conditions persist Monday night into Tuesday. North
winds peak Tuesday afternoon and evening with continued steep seas
south of Cape Blanco. Additionally, localized gusts up to gales and
areas of very steep hazardous seas may develop late Tuesdday between
5 to 30 nm from shore from Cape Ferrelo southward. Steep seas may
spread farther north on Wednesday before winds and seas ease on
Thursday.


&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory from 2 PM Monday to 11
     PM PDT Tuesday for PZZ356-376.

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

&&

$$