Mount Shasta, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

870
FXUS66 KMFR 190550
AFDMFR

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

.UPDATE...Aviation Discussion Updated.

&&

.AVIATION...19/06Z TAFs...Along the coast and just offshore. A
strong storm will bring moderate to strong winds along the coast and
offshore overnight. 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 to 08-12z. Moderate to heavy rain will
bring a mix of IFR and MVFR overnight, with these conditions
continuing on Friday. Expect some improvement Friday afternoon and
evening, with conditions becoming VFR with areas of MVFR in showers.

Inland, west of  the Cascades, moderate to strong winds aloft is
resulting in low level wind speed and directional shear through
around 08-12z. Stronger winds are likely to surface at Medford, with
gusts up to 30 kts possible through around 08z. Ceilings will lower
from north to south between 06-11z. A mix of IFR/MVFR ceilings
with MVFR visibilities are expected tonight and Friday. Some areas,
such as Roseburg, will  see improvement to VFR late Friday afternoon
and evening.

East of the Cascades,  strong winds will be the main concern
this through tonight for most locations, including Klamath
Falls. Guidance shows southwest wind gusts peaking at 30-35 kt
overnight for Klamath Falls. Winds will remain gusty through Friday
afternoon. Ceilings will be VFR with areas of MVFR and
mountain obscurations through 12z, then lower to MVFR with local IFR
and widespread mountain obscurations Friday morning. These
conditions will continue into Friday afternoon. Then expect a mix of
VFR with areas of MVFR Friday evening as precipitation decreases.
Snow levels will also lower Friday evening, resulting in areas of
light snow showers and MVFR ceilings/visibilities.

&&

.MARINE...Updated 830 PM PST Thursday, December 18, 2025...A
strong cold front will move southward along the coast tonight.
Gale force south winds, rain and very steep, hazardous seas will
continue. Gradually, winds will shift to the northwest and ease by
early Friday morning and precipitation will turn to showers. Even
so, seas will remain elevated through early Saturday morning.
We`ve added a small craft advisory from 7 am Friday to 7 am
Saturday to account for the steep seas. Calmer conditions are
possible over the weekend before active weather returns early next
week. -Spilde

&&

.PREV DISCUSSION... /Issued 740 PM PST Thu Dec 18 2025/

DISCUSSION...A strong front is moving into the area and will
bring moderate to heavy rain as well as strong winds. Winds have
increased over the area with gusts of 50-60 mph observed at the
coast, over the coastal mountains and over some higher mountains
inland. In the Medford area, winds have gusted to around 30 mph. Winds
will peak tonight for areas west of the Cascades and tonight into
Friday morning for areas from the Cascades east and over northern
California. Then, strong and gusty winds continue Friday afternoon
areas from the Cascades east on Friday.

Moderate to heavy rain has moved inland over Coos and northwest
Douglas counties early this evening. Rain rates of 0.20 to 0.35
per hour are occuring in the heavier bands of precipitation.
Models remain on track showing this areas of moderate to heavy
precipitation spreading inland tonight and Friday, from northwest
to southeast across the area. Heaviest rainfall is expected along
the coast, coastal mountains in to the Cascades and western
foothills. These areas may see 2 to 4 inches of rainfall. The
River Forecast Center forecast is currently keeping mainstem
rivers below flood stage. We are continuing to monitor the South
Fork of the Coquille at Myrtle Point which is expected to near,
but stay below, bankfull. Small streams in the areas of heavy
rainfall, especially along the coast, coastal mountains and into
Douglas County are likely to run high but widespread flooding is
not anticipated at this time. Heavy rain could result in some
localized nuisance flooding along with ponding of water on
roadways. Travelers should take precautions if driving in heavy
rain, slow down, keep plenty of extra space between their vehicle
and the vehicle in front of them and plan for extra travel time.

Snow levels will be generally high, 6500-8500 feet but will lower
on the backside of the front on Friday down to around 4000-5000
feet then lower, down to 2500-3500 ft in light showers Friday
evening. High resolution models indicate there may be a brief
period of moderate to heavy snow in the Crater Lake and Diamond
Lake areas late Friday morning as the back end of the frontal band
moves through and snow levels lower. This is highest for the
Crater Lake areas, where there is a potential (60%) for an hour
or two of 0.5 to 1.0 inch per hour snowfall rates before
precipitation rates decrease.

PREV DISCUSSION... /Issued 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

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.

     Small Craft Advisory from 7 AM Friday to 7 AM PST Saturday for
     PZZ350-356-370-376.

&&

$$