640
FXUS66 KMFR 272118
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
Issued by National Weather Service Portland OR
218 PM PDT Tue Oct 27 2026

.KEY MESSAGES...

* Persistent low pressure this week brings seasonably active
  weather with mainly low impacts.
* Steady rainfall will taper off to showers from west to east this
  afternoon, with showers coming to an end for most locations by
  this evening.
* Temperatures remain relatively steady through the week, fluctuating
  within a range from around 10 degrees below normal to near
  normal.
* Excellent model agreement through Friday with occasional light
  shower chances, mainly for Coos and Douglas counties northward
  during Wednesday and also Thursday night.
* Either a weak or very weak system moves inland on Saturday.
  Light shower chances on Saturday will be highest at the coast,
  possibly extending inland during the afternoon or evening.
* High pressure will likely bring drying and modest warming for
  Sunday through Tuesday.

&&

.DISCUSSION...A quick moving low pressure will continue tracking
eastward through Oregon this afternoon. Steady rainfall will
transition to showers from west to east this afternoon, gradually
coming to an end for most locations by this evening. Snow levels
will hover around 5000-5500 ft today, so if youre traveling
through the Cascades this afternoon be prepared for periods of
wintry weather. We dont expect much snow up that way, maybe up to
2 inches total by early this afternoon, but given its early in
the season, its worth mentioning.

A broader area of low pressure, now over northern British Columbia,
will retrograde slightly, tracking south-southwest toward
Vancouver Island by Wednesday. The greatest shower activity in the
onshore flow pattern will be focused north of our area. But, Coos
and Douglas, possibly even into northern Curry/Josephine,
counties should receive a measurable amount of showers under
persistent cloud cover. Elsewhere, breaks in the cloud cover are
expected and should allow for high temperatures to reach a few to
several degrees higher than today.

The low will meander a bit farther south Thursday into Friday, with
our region likely to be between shortwaves for a reduced chance
of light coastal showers on Thursday. Compared to the GFS, the
ECMWF does indicate a bit more low level moisture that would be
sufficient to generate very light showers north of Cape Blanco.
The blended 40% probability of rain and trace to a barely
measurable hundredth or so is appropriate. The low is expected to
remain offshore of Washington and northern Oregon, with a slight
backing to more of a due southwest flow aloft on Thursday night
through Friday night. This will keep the more favorable dynamics
and deeper moisture aimed north of our area, and conditions on
Friday should resemble those of Thursday.

For now, the story for Saturday is much the same as it was
yesterday. Uncertainty increases a bit, enough to make the
difference between whether light or very light showers remain
confined to the coast, or extend to the Cascades with a slight
chance possibly warranted for the east side. For the daylight
hours, the probability will be highest for (and possibly limited
to) the coast. The ECMWF suite of solutions indicates a higher
probability of west side focused rain, a sharper trough, than the
GEFS. This would mean around 0.05 to 0.10 inches for the coast
rather than a trace to 0.02 inches. Toward sunset into the
evening, rain chances could spread farther inland. This
uncertainty is expressed by 20-30% rain chances being mainly west
and north of Jackson County for the afternoon, ahead of a more
widespread 20-40% chance for the evening.

Despite the differences in strength, models are in good agreement
on slight rain chances lingering east of the Cascades late
Saturday night ahead of ridging early next week. The ridge will
provide drying and modest warming Sunday into Tuesday. From late
day 7 through day 10, model uncertainty quickly increases with a
near even split between whether ridging will linger into mid-week,
or shift to the Rockies with a return to wet weather for the
Pacific Northwest.       /BR-y

&&

.AVIATION...27/18Z TAFs...A trough is moving through areas near
and west of the Cascades late this morning with most of the
precipitation occurring in SW Oregon. Light to moderate rain, MVFR
ceilings and higher terrain obscuration will accompany this
disturbance with local IFR conditions at times in areas of heavier
precipitation. As this system shifts east of the Cascades this
afternoon, precipitation will become more sparse/showery and
conditions should improve. Conditions should mostly remain VFR in
south central Oregon and far northern California, though may
briefly lower to MVFR in any shower. Conditions should improve
to VFR all areas this evening.

Late tonight into Wednesday morning, after 09Z, another weaker
trough will bring light rain to the coast north of Cape Blanco
with a similar mix of IFR/MVFR for Coos and Douglas counties. VFR
will persist elsewhere, except there is a 20-30% possibility of
IFR fog in some valleys around sunrise.        -Spilde

&&

.MARINE...Updated 1230 PM PDT Tuesday, October 27, 2026...Unsettled
weather with occasional showers will continue through the week.
Winds are expected to remain below advisory strength. A series of
seasonably weak disturbances will produce the strongest northwest
winds in the Washington and northern Oregon offshore waters, which
will push fresh swell into the southern Oregon waters. Fresh
west-northwest swell dominated seas will continue steep seas
through late this afternoon. Seas become less steep this evening
with fresh north-northwest swell persisting, along with a low
west-northwest swell, through the week. The active pattern is
expected to persist late in the week with slight, gradual
improvement in conditions. The outlook is that a long period west-
northwest swell may build from 2 ft at 21 seconds late Sunday to
6-8 ft at 17 seconds on Monday.       /BR-y

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 5 PM PDT this
     afternoon for PZZ350-356-370-376.

&&

$$