457
FXUS66 KMFR 152050
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
150 PM PDT Tue Sep 15 2026

.KEY MESSAGES...

* Showers are possible late this afternoon and early evening but
  these should be very isolated in nature with little rainfall

* Showers and thunderstorms are possible Wed and Thurs
  afternoon/evening with the main threats being lightning and
  gusty erratic outflow winds

* Temperatures warm through the weekend with above normal
  temperatures expected

&&

.DISCUSSION...

Water vapor imagery depicts an area of low pressure over the
state of Washington. Models are very consistent with bringing this
low south, eventually cutting off from the mean flow, and
meandering over the forecast area through Friday before this low
moves eastward. This low will help support showers and
thunderstorms over the next few days before those chances decrease
on Friday as the low starts to exit the region.

For today, the low will just begin to settle in over the forecast
area, eventually cutting off from the main flow later tonight. We
will have chances for showers late this afternoon and through the
overnight hours as the low starts to settle in over the area.
While an isolated thunderstorm cannot be ruled out, this chance is
low and these should be mostly showers in nature. Given the low
isn`t moving, these chances will persist overnight for eastside
area. Very little rainfall is anticipated with any showers that
happen to develop.

For tomorrow, two opposing jet streaks will be noted on the
northwest side and southeast side of this low. These will help
maintain the low over the forecast area. The upper jet on the
northwest side (stronger of the two), along with added moisture,
will help develop showers and thunderstorms Wednesday afternoon
and evening. The center of the low will shift slightly south and
southwest due to the stronger of the jets steering it south. This
orientation will develop showers/thunderstorms on the eastside,
and the flow should bring these chances over the Cascades and into
some westside areas. The question is of course how much of this
will be downsloped on the westside. DCAPE values due suggest that
a couple storms could potentially produce strong outflow gusts
near 45 mph. This could become more complicated if terrain helps
induce stronger outflows. Wednesday does appear to be the higher
risk day between Wed/Thur for both lightning and strong outflow
gusts, but a lot will depend on activity Wednesday as there wont
be much airmass change.

On Thursday, there is some question as to how much the atmosphere
will be worked over as this low remains in place without an
airmass change. That said, CAPE will continue to be present, and
the thinking is we will see continued chances for showers and
isolated thunderstorms. These chances will be primary for areas
along/near the Cascades, northern California, and eastside areas.
Not expecting much--if any--activity for westside areas. Similar
threats involving lightning and gusty outflow potential albeit
slightly less of a threat than Wednesday.

The low starts to exit on Friday, and this will be replaced with
high pressure over the forecast area through the weekend. This
will resulting above normal temperatures this weekend, including
the potential for lower 90s across some westside valleys.

-Guerrero

&&

.AVIATION (18Z TAFs)...

TAFS will start out with plenty of sunshine and mostly clear skies
for the terminals, but high clouds will start to infiltrate into the
region this afternoon. Expecting another marine stratus layer to
bring IFR/LIFR conditions to KOTH overnight through Wednesday
morning. However, inland sites are not expecting any low to mid
level cloud decks. Need to consider rain chances this evening for
KLMT, but at this time confidence was not high enough to include in
this TAF cycle, but there is a small chance (20-25%) to see a shower
or isolated thunderstorm after sunset and possibly through Wednesday
morning. May reevaluate and add this mention in subsequent TAFs.

-Guerrero

&&

.MARINE...Updated 100 PM PDT Tuesday, September 15, 2026...Gusty
north winds and steep to very steep seas will continue through this
evening. Strongest winds and steepest seas are expected south of
Gold Beach and beyond 5 nm from shore through tonight. Steep seas
will expand northward tonight maintaining steep seas through
Wednesday evening for all area waters. Seas and winds lower by
Thursday.

-Guerrero

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT
     Wednesday for PZZ350-356-370-376.

Hazardous Seas Warning until 11 PM PDT this evening for PZZ356-
     376.

&&

$$