609
FXUS66 KMFR 171209
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
409 AM PST Mon Nov 17 2025

...New Aviation Section...


.AVIATION (12Z TAFs)...

A passing trough will bring light rainfall through this afternoon
before we start to see diminishing trends this evening. Low level
saturation will lead to MVFR conditions at times, but VFR should
be more dominate through this cycle. Tonight could be a tricky
forecast as we see split flow develop, but generally speaking
expecting VFR conditions to dominate through this cycle.

-Guerrero

&&

.PREV DISCUSSION... /Issued 252 AM PST Mon Nov 17 2025/

DISCUSSION...

Key Points:

* Overall, little to minimal impacts expected this week
* Light rainfall will continue today/tonight
* Light snowfall at higher elevations continues today/tonight
* Next round of light precipitation Wed through Thurs
* Lingering precipitation continues through end of week for
  coastal areas and Umpqua Basin

Further Details:

Precipitation will continue through today as a split flow pattern
develops. A cut-off low will split from the southern edge of a
passing through, and this will allow for lingering precipitation
through this evening mainly for northern California as this cut-off
low slowly meanders south/southeast through tonight. We will see a
brief break in activity tomorrow before another weak embedded
shortwave passes within the chaotic pattern. This will lead to
additional light precipitation, including light snowfall amounts for
higher elevations like the Cascades and western Siskiyou County.
Then a stronger low/shortwave will develop Wednesday afternoon, and
pass through the region on Thursday as a cut-off low as it splits
from the mean flow. This could bring another punch in regards to
precipitation amounts. Rainfall along and near the coast will be on
the order of 0.50"-1.00" through 24-36 hours Wednesday
afternoon/evening through Thursday. Through this stretch a couple
inches of snowfall could fall around Crater Lake and associated
elevations. Higher amounts possible for Mt Shasta. Not expecting any
impacts across these areas as amounts will be too low for areas that
are inhabited/traveled. Also not seeing any wind threats through
this stretch.

Perhaps the biggest impact these week could be frost/freeze
potential Wednesday morning for westside areas. However, uncertainty
does exist as fog could limit radiational cooling and hence low
temperatures may not be cold enough for some areas/elevations. On
the other hand, the low level moisture could bring a higher risk for
frost formation if we are allowed to maximize radiational cooling
overnight. At this time, not expecting widespread frost/freeze to
come to fruition, but will continue to monitor this threat,
especially isolated areas. Some elevations will have a greater risk,
but valley floors like Medford have a greater risk for fog and hence
limited frost/freeze.

-Guerrero

AVIATION (06Z TAFs)...

An cold front is passing onshore, producing rain for most areas
west of the Cascades this evening, and spreading to the east
overnight. Periods of IFR to LIFR conditions are expected as this
front moves through, along with terrain obscurations, especially
along the western and northern slopes. Showers will continue into
the morning, then taper off through Monday afternoon and evening,
with conditions improving to VFR or high MVFR for most areas by
Monday evening.

-BPN

MARINE...Updated 200 AM PST Monday, November 17, 2025...North winds
will continue to be on the stronger side today around 20-30 kts
sustained with occasional gusts near 40 kts. The increase in
northwest winds will push wave heights higher with seas peaking at a
very steep 15 feet this morning. Seas will gradually lower by Monday
evening, although conditions will still be hazardous to smaller
craft.

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 night into Friday.

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 10 AM PST
     Wednesday for PZZ356.

Small Craft Advisory until 4 AM PST Tuesday for PZZ350-370.

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

     Small Craft Advisory from 4 PM this afternoon to 10 AM PST
     Wednesday for PZZ376.

&&

$$