934
FXUS66 KMFR 161152
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
352 AM PST Sun Nov 16 2025

.Updated AVIATION Discussion...

&&

.AVIATION...16/12Z TAFs...LIFR conditions will prevail through
the morning for the West Side Valleys along and west of the I-5
corridor, with VFR conditions for areas eastward. These lower
conditions should clear out before Sunday afternoon, with rain and
MVFR ceilings developing Sunday morning over eastern portions of
Lake and Modoc counties. Meanwhile, an approaching front will bring
light rain and MVFR ceilings to the coast around 15Z. The
approaching front will lift the valley ceilings from late morning
into the afternoon. The frontal passage will bring moderate rain
with lower visibilities and lower ceilings to the coast Sunday
evening. The front will linger over northern California Sunday night
into Monday with periods of rain, widespread IFR/MVFR, and mountain
obscuration across the area. Additionally, expect gusty south winds
to develop in the Shasta Valley and east of the Cascades later this
morning and persist into the evening hours.

&&

.PREV DISCUSSION... /Issued 224 AM PST Sun Nov 16 2025/

DISCUSSION...Quiet weather continues this morning, with satellite
imagery showing fog in many of the typical places west of the
Cascades. Meanwhile, higher level cloud cover is moving into the
forecast area both from the west along the coast and also from the
south into the southern and eastern portions of the forecast
area. Radar shows some light returns moving into eastern Modoc and
Lake Counties. This is associated with a low pressure to the
southeast that will open into a trough and continue moving
eastward today. As this happens, precipitation will continue to
stream into the eastern portions of Lake/Modoc Counties and
southerly winds increase in the Shasta Valley and across the
higher terrain east of the Cascades later this morning and persist
into this evening. Winds look to remain below advisory criteria
with this increase, but gusts of 25-35 mph can be expected with
some higher gusts up to 40 mph possible.

Meanwhile, the next Pacific storm system approaches the area this
afternoon/evening, bringing the return of precipitation from west to
east along with another round of breezy winds. Once again, this
system will split with the southern branch taking most of the energy
and precipitation into California and the northern portion moving
through Washington and northern Oregon. This pattern will focus the
best precipitation chances and highest amounts (1"-2")south of the
OR/CA border and along the coast south of Cape Blanco. Downsloping
flow will likely result lower precipitation amounts here in the
Rogue Valley (around 0.25"). Initial snow levels with this system of
7000-8000 feet will keep snowfall to the highest peaks and
ridgelines. Snow levels drop to 5000 feet through Monday, but with
the bulk of the precipitation already through the region, snowfall
amounts will be rather meager. Latest forecast and guidance
maintains snowfall amounts at Crater Lake to be around 1-3 inches.

Precipitation eases across the area Monday night but a cold air mass
could linger over the area into midweek, bringing daytime high
temperatures that are around 5 to 10 degrees below seasonal norms.
This could result in some chilly nights for the West Side Valleys
north of the OR/CA border with low temperatures falling to the low
to mid 30s in portions of the Rogue/Applegate/Illinois Valleys.
There`s more uncertainty for the Umpqua Basin where fog tends to
keep temperatures elevated and dewpoints remain higher. At this
time, it looks like Tuesday night/Wednesday morning could be the
coldest, and this will be a time we`ll need to watch for the
potential of frost or freeze conditions for West Side Valleys. Of
course, the fly in the ointment will be the potential for fog in
these valleys, which, like the Umpqua Basin, would keep temperatures
elevated and limit the extent of frost/freeze.

Another low pressure system approaches the area late Wednesday into
Thursday, but there remains uncertainty regarding how far inland
this trough makes it as it dives southward. Both ECMWF and GFS
deterministic imagery now show the system impacting at least areas
from the Cascades west, but the EC is farther inland as it dives
into California while the GFS keeps the low`s center more offshore.
These differing solutions will have implications on how much
rainfall and strength of the winds that impacts the region. For now,
the forecast utilizes the NBM which maintains generally low impact
conditions, but this may need to be updated as models come to a
better agreement on the trajectory of this system. Snow levels are
expected to hover around 5000 ft, so winter impacts should be
limited as well.

Beyond Thursday, there is general agreement on flat ridging, which
would bring a period of drier conditions, at least for the southern
and eastern portions of the region. The majority of the ensemble
suite maintains a drier forecast through the weekend, but there are
decent minority that would continue rainfall through the weekend.
Stay tuned as details become more clear.

MARINE...Updated 130 AM PST Sunday, November 16, 2025...Sub-
advisory winds and swell dominated seas are expected to persist
through this morning. South winds will increase today ahead of a
cold front. This increase in south winds will be brief, with winds
reaching Small Craft Advisory strength before quickly shifting to
northwest and becoming stronger this evening. North to northwest
winds could approach gales south of Cape Blanco through tonight,
but will gradually ease Monday morning. Northwest swell increases
as well today, and when combined with steep wind waves, seas will
become steep to very steep tonight, peaking in the 13 to 17 ft
range at around 12 seconds. Seas will lower some Monday afternoon
as wind seas ease, but remain steep through Monday night.

Conditions improve Tuesday into Wednesday then another frontal
system is expected late Wednesday into Thursday, though, confidence
is low on the trajectory of the next storm system. Some guidance
brings the system inland, while other guidance keeps it farther
offshore as it moves southward and these differences will have
implications on how strong winds will be. Despite the uncertainty in
wind strength, confidence is higher for a heavy long period swell to
build into the waters Thursday.

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory from 1 PM this
     afternoon to 4 AM PST Tuesday for PZZ350-356-370.

Hazardous Seas Warning from 4 AM to 4 PM PST Monday for PZZ350-
     356-370-376.

     Small Craft Advisory from 1 PM this afternoon to 4 AM PST Monday
     for PZZ376.

&&

$$