776
FXUS66 KMFR 152219
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
219 PM PST Mon Dec 15 2025

.DISCUSSION...The first in a series of fronts is moving into the
area bringing rain to the coast and coastal mountains and gusty
winds. Strongest north of Cape Blanco. Precipitation will spread
farther inland, with winds increasing east of the Cascades. The bulk
of the precipitation will be along the coast, coastal mountains and
Cascades. Satellite image and radar are showing moderate to
occasionally heavy precipitation with a few lightning strikes which
is partially being aided by an upper level jet moving towards
southwest Oregon. Isolated thunderstorms should remain confined to
the south Oregon coast and inland in Curry and western Josephine
County into early this evening.

Most of the Rogue Valley could end up dry during the day
Monday with not much more than occasional showers late this
afternoon and early evening due to the non-favorable southwest flow.
East of the Cascades will likely get little to rainfall, but it will
be windy into early this evening.

More fronts will follow the rest of the week into next weekend
bringing more rain, moderate to strong winds and higher elevation
mountains snow. Detail`s on the timing mentioned below could vary
with each individual storm, so be on the lookout for updates to the
forecast in the days to come.

A second and stronger system will arrive Tuesday night into
Wednesday brining moderate to heavy rain to the coast, coastal
mountains and Cascades. Moderate to occasionally strong winds are
possible at the coast. Not all of the ingredients are there for a
winds to reach high wind warning criteria at the coast, but they do
for east of the Cascades, especially near and at the ridges.
guidance shows 700 mb winds between 60-70 kts Tuesday night through
Wednesday morning, then decreasing some Wednesday afternoon. Given
the above, the High Wind Watch has been upgraded to a High Wind
Warning for the higher terrain in Lake, Modoc and potions of Klamth
County. At the same time a Wind advisory has been issued to cover
the remainder of Lake, Modoc and to include more of Klamath County.
Please see NPWMFR for more details.

Snow levels will be between 7000-8000 feet Tuesday, then lowering
between 4500-5500 feet Wednesday. Therefore we`ll see rain change
over to snow late Tuesday night into Wednesday morning with 3-5
inches possible up towards Willamette Pass, and 2-4 inches around
Diamond and Crater Lake by late Wednesday morning.

Precipitation will gradually diminish later Wednesday morning
through the afternoon and we`ll catch a relative break in the action
from Wednesday afternoon into most of Wednesday night.

A stronger storm will arrive Thursday and last through Thursday
night bringing another round of moderate to heavy precipitation and
strong winds. Strong winds will be a concern Thursday, especially
east of the Cascades where some of the guidance shows 700 mb winds
between 70-80 kts over a large chunk of real estate east of the
Cascades. It`s also worth noting, strong winds east of the Cascades
could be of longer duration (12-18 hours).

Although not as high of a concern, moderate to strong winds will be
a concern in the Shasta Valley. However the wind direction in the
Shasta Valley has a westerly component which could put a cap on the
magnitude of the winds. Guidance shows the Medford to Redding
gradient between 8-9 mb. So it`s something we`ll have to keep a
close watch on.

The coast is another story. Current gradients between Arcata and
North Bend peak out at almost 10 mb Thursday afternoon and night
which is significant enough for high winds, and guidance shows an
enhanced area of strong winds close to 70 kts Thursday afternoon
from about Cape Blanco north.

Thre`s good agreement the storm that arrives Thursday will have an
atmospheric river (AR) component, with a long fetch of moisture
extending southwest towards 160W, with the source region coming from
the tropics. Additionally, there is favorable upslope flow along the
coastal mountains and Cascades. The net result could be a prolonged
period (24-36 hours) of heavy precipitation for these areas along
with moderate to occasionally heavy rainfall elsewhere. Given the
lack of rain the last few weeks, rivers are pretty low, but they
will come up over time and we could be looking at potential flooding
on the Coquille towards the end of the week. Another factor that
could put a cap on the flooding concerns is little to no snowpack.
Therefore there will be no additional contribution from snowmelt
going into the rivers. Another item worth noting is there are some
indications the core of heavier precipitation could shift north of
the Umpqua Divide for a brief period of time Thursday afternoon into
Thursday night before shifting south over southern Oregon and
Northern California Friday. Keep in mind the details could change,
so keep a eye out for updates in the days to follow.

Looking into next week leading up to Christmas Holiday, there`s
strong evidence that`s being supported by the ECMWF, GEFS ensemble
means and clusters, we`ll be heading into a colder and wet pattern
with storms originating from the Gulf of Alaska as we get towards
the following weekend through at least Christmas Day.

These typically result in colder temperatures, and precipitation
with lower snow levels. The pattern shows below normal 500 mb
anomalies with a stronger upper troughing in the western U.S. with
ridging and above normal 500 mb anomalies in the northeastern part
of the U.S. The anomalies being shown are pretty significant this
far out which is unusual since they tend to "wash out" and lean more
towards climatology.

This is a almost the opposite of the pattern we have experienced for
almost the last three weeks, with stronger ridging in the western
part of the U.S. and deep upper troughing in the northeastern part
of the U.S. In other words, the switch basically gets flipped as the
overall pattern changes. -Petrucelli


&&

.AVIATION...15/18z TAFs...The main concern ion the short term will
be low level wind speed shear along the coast into early this
afternoon, including North Bend. Stronger winds should surface at
North Bend early this afternoon, and at the same time winds aloft
will be diminishing, thus ending the concern for low level wind
speed shear. MVFR and occasional IFR ceilings are expected in
precipitation through the TAF period, although could not rule out
brief periods of VFR ceilings this evening and tonight as the bulk
of the precipitation shifts south, but confidence is not high enough
to include improving conditions in the TAF.

Inland west of the Cascades, VFR ceilings are being observed and
should last for most of the afternoon, the exception will be in
Roseburg as the front moves south bringing lowering ceilings and
partial mountain obscuration north of the Umpqua Divide between 21-
22z. The medford terminal should remain VFR through 0z, then
ceilings will lower as the front moves in. Once the front moves
south, there could be enough clearing along with a more stable
atmosphere and ample low level moisture for low clouds and fog to
develop late tonight into Tuesday morning for the Valleys, including
the Roseburg and Medford terminals. The timing of when the lower
conditions develop in the TAF could change, so watch for updates.

East of the Cascades, VFR conditions are expected through the TAF
period, although the higher terrain could be partly obscured towards
0z, with ceilings possibly hovering towards 3000 feet at Klamath
Falls for a few hours this evening. -Petrucelli


&&

.MARINE...Updated 100 PM PST Monday, December 15, 2025...The first
round of south gales north of Cape Blanco is winding down this
afternoon. Very steep and hazardous seas will remain elevated, but
become less steep as they transition to swell dominated this evening
and persist through much of Tuesday. The next front is expected late
day Tuesday, bringing another round of southerly gales that quickly
switch to the northwest, and remain strong, late Tuesday night. This
will build seas again, becoming very steep and hazardous Tuesday
night across all waters, with gales expected north of Cape Blanco.

Winds ease late Wednesday morning, but seas will remain steep
through Wednesday night. Another, more persistent front will take
aim at the coast late Wednesday night/early Thursday morning,
bringing a longer duration of strong winds. Strong gales are likely
with this system, with a 20-40% chance of storm force (>55kt) gusts
possible north of Cape Blanco on Thursday morning. Winds will
gradually ease from north to south late Thursday night into Friday
morning, but seas are likely to remain steep to very steep through
Friday. Moderate to heavy rain will accompany each front this week.
/BR-y


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Warning from 10 PM Tuesday to 4 PM PST Wednesday for
     ORZ030-031.

     Wind Advisory from 10 PM Tuesday to 4 PM PST Wednesday for
     ORZ029>031.

CA...High Wind Warning from 10 PM Tuesday to 4 PM PST Wednesday for
     CAZ085.

     Wind Advisory from 10 PM Tuesday to 4 PM PST Wednesday for
     CAZ085.

PACIFIC COASTAL WATERS...Hazardous Seas Warning until 4 PM PST this
     afternoon for PZZ350-356-370-376.

     Small Craft Advisory until 4 PM PST Tuesday for PZZ350-356-370-
     376.

     Gale Warning until 4 PM PST this afternoon for PZZ350-370.

&&

$$