Mount Shasta, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

610
FXUS66 KMFR 182213
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
213 PM PST Thu Dec 18 2025

.DISCUSSION...A potent storm system is poised to pounce on
southern Oregon and far northern California within the next 12 to
24 hours. A deepening surface low is moving onshore along the
US/Canadian border this afternoon, and the associated cold front
lies just to our north. This front will push south this evening
through tonight, producing strong winds and moderate to heavy rain
across the forecast area. Winds have already increased across the
area, with some locations along the coast seeing gusts above 50
mph, and some mountaintop stations exceeding 60 mph. Winds will
increase further, peaking this evening for the coast, inland this
evening and tonight, and for the East Side, peaking overnight but
remaining windy through much of Friday. Of note, the MSLP
gradients are nearly double that of a "typical" winter system,
and 700mb winds are expected to peak above 80 kt. As such, strong
winds are forecast for nearly the entire area, and numerous Wind
Advisories and High Wind Warnings remain in effect. More details
on these can be found at PDXNPWMFR.

Also of concern during this event is rain. While the lack of rain
in the past couple of months has been concerning, it will help us
now in that for the most part, rivers and streams have the
capacity to handle the runoff from the heavier rains expected
through Friday morning. There have been many changes to the
forecast river levels today, and as of now, no local rivers are
forecast to reach flood stage, although the South Fork of the
Coquille at both Powers and Myrtle Point are forecast to get to
action stage. Many smaller streams and creeks may briefly
overflow, and urban areas may see ponding, especially in areas
with poor drainage, but otherwise, flooding impacts will be minor.

As precipitation tapers to showers behind the front Friday, snow
levels will lower quickly, reaching 3000-4000 ft by Friday
afternoon, then as low as 2000 feet by Saturday morning.
Precipitation should be negligible by the time snow levels drop
that low Friday night into Saturday, but we can not rule out a few
flurries at low elevations. Meanwhile, a few inches of snow,
generally less than 6 inches, will fall over the Cascade
passes, with some higher amounts over the peaks, such as at Crater
Lake.

After a brief break Saturday, the next system arrives Saturday
night into Sunday as a surface low forms off the northern
California coast then pushes inland, quickly followed by another
front from the northwest Sunday night into Monday. The active
pattern continues with additional storms through next week and
potentially into the weekend. Each of these systems will bring
wind, rain, and mountain snow to the region, including a system
that looks to develop just offshore of Oregon right around
Christmas. Model snow levels throughout this time will hover
between 3000 and 4000 feet, so while the passes could see
impactful snow during busy holiday travel times, East Side valleys
should see only light accumulations, with West Side valleys
remaining snow-free. However, should any of these systems take a
more southerly route, colder air could infiltrate into the region,
lowering snow levels further. We will keep an eye on things as
they evolve, and update as necessary. -BPN

&&

.AVIATION...18/18Z TAFs...Along the coast and just offshore. A
strong storm will bring moderate to strong winds along the coast and
offshore. Winds aloft are very strong and there is enough difference
in wind speed and direction for low level wind speed and directional
shear to continue through this evening. Moderate to strong winds are
likely to continue through 12z tomorrow, but winds aloft should
gradually diminish late this evening and tonight. Ceilings will see
saw back and forth between IFR and MVFR for most of the TAF period.
The exception is at North Bend where VFR ceilings are expected for
the start of the TAF period, then lowering this afternoon and
tonight.

Inland, west of the Cascades, moderate to strong winds aloft will
result in low level wind speed and directional shear despite the
stronger surface winds at Roseburg. Stronger winds are likely to
surface at Medford, but not until later this afternoon with gusts up
to 30 kts possible this evening (3-5z). With the core of the heavier
rain to the north, ceilings will remain VFR through this evening,
then lowering from north to south. Medford could remain VFR for most
of the TAf period, but have kept in the lower conditions towards 15z.

East of the Cascades, strong winds will be the main concern this
afternoon through tonight for most locations, including Klamath
Falls, guidance shows southwest wind gusts peaking out just over 30
kts this evening, but suspect this is underdone and we`ll keep gusts
at 35 kts in the Klamath Falls TAF. Winds should back towards the
south late this evening and tomorrow and gradually diminish.
Ceilings will remain VFR, although the higher terrain could end up
partly obscured this afternoon, and more likely late tonight into
tomorrow morning. -Petrucelli



&&

.MARINE...Updated 230 PM PST Thursday, December 18, 2025...A strong
front will move through the region late today/tonight, and
conditions will quickly deteriorate today through Friday. Winds will
quickly ramp up to widespread gales, with storm force winds
developing from Gold Beach northward within 40 nm from shore. Expect
widespread south winds of 30 to 40 kt with gusts around 50 kt, with
storm force winds of 40 to 45 kt and gusts around 60 kt. Wind driven
seas will become very steep and chaotic at 18 to 24 ft. A Storm
Force Warning remains in effect this morning through Thursday
evening, with a Gale Warning in effect for all other areas.

The front will move southeast over the marine waters tonight with
winds shifting from south to northwest and diminishing, first over
the northern waters, then in the southern waters by Friday morning.
Wind speeds will be much weaker Friday morning behind the front
(compared to today) and will remain relatively lighter through the
weekend. Seas are expected to remain elevated late tonight into
Friday morning, then they will also gradually diminish later Friday
afternoon into the weekend. Lastly, It`s also worth noting, moderate
to heavy rain will accompany both fronts resulting in limited
visibility.

&&

.BEACH HAZARDS/HIGH SURF...A strong storm will bring storm force
winds to the marine waters and strong damaging winds to the coast
today. These winds will build very steep ocean waves that will
result in large breaking waves of 20 to 25 ft in the surf zone. This
will lead to hazardous beach conditions today for area beaches from
Port Orford northward. If you have plans to visit area beaches
today, stay away from the surf zone during this time as beaches and
shorelines will become dangerous places. Jetties, rocks and logs are
NOT safe. Inundation of low lying areas is possible and this could
result in beach erosion or damage to exposed infrastructure.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory until 4 AM PST Friday for ORZ023>025-029>031.

     High Wind Warning until 4 PM PST Friday for ORZ021-022-030-031.

     High Surf Advisory until 10 PM PST this evening for ORZ021.

CA...Wind Advisory until 4 AM PST Friday for CAZ081-084-085.

     High Wind Warning until 4 PM PST Friday for CAZ085.

PACIFIC COASTAL WATERS...Gale Warning until 1 AM PST Friday for
     PZZ350-356-370-376.

     Hazardous Seas Warning from 1 AM to 7 AM PST Friday for PZZ350-
     356-370-376.

     Storm Warning until 7 PM PST this evening for PZZ350-356-370-
     376.

&&

$$