520
FXUS66 KMFR 172330
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
430 PM PDT Fri Apr 17 2026

.Updated AVIATION Discussion...

&&

.AVIATION...18/00Z TAFs...VFR conditions will prevail for the next
24 hours with generally light winds. A similar scenario of patchy
southwest Oregon valley IFR is possible for early Saturday morning,
but there will be increased high level cloud cover overnight that
could limit this. The highest chance would be in the Coquille Basin,
including North Bend. /BR-y

&&

.PREV DISCUSSION... /Issued 134 PM PDT Fri Apr 17 2026/

DISCUSSION...Some shallow fog was observed in the Illinois,
Coquille, and Umpqua valleys this morning, along with
temperatures right at or just above freezing. In the Rogue
Valley and the valleys of Western Siskiyou County, skies remained
mostly clear, and temperatures dropped into the upper 20s. With
high pressure building in today, a brief warming trend begins,
and temperatures will move towards well above normal through the
weekend. The area should remain dry through at least the first
half of the weekend.

Also, increasing mid to high level clouds are expected tonight,
which along with the warming air mass, should preclude any
widespread frost west of the Cascades, although some isolated
areas, such as in the southern Illinois valley or the higher
elevation valleys, could see some spots of frost.

A slow moving upper level low will take position to our west by
Sunday, then gradually dig south and east, finally passing to our
south sometime midweek. Both southerly flow and moisture aloft
will strengthen Saturday night into Sunday with thicker high
clouds expected as the low approaches. The main effect of the
approaching upper level closed low will be an increase in south
to southwest winds for the Shasta Valley and the east side. The
strongest winds (gusts up to 45 mph) are expected in the southern
Shasta Valley near Weed during Sunday afternoon, secondarily in
Lake County near Summer Lake and Silver Lake on Monday and Tuesday
(gusts up to 35 mph).

The downslope flow on Sunday (and possibly through Tuesday) will
very likely keep the Shasta and Rogue valleys dry, but a few
sprinkles can`t be completely ruled out from the coast to the
Cascades. Even at the coast, a relatively dry lower atmosphere
should keep things mainly dry into Sunday evening. The probability
of showers will trend higher later Sunday night into Wednesday,
with ensemble data showing a wider spread in solutions but also
higher average precipitation amounts Tuesday night into Wednesday.
The probability of thunderstorms will be highest during Monday
and Tuesday in the late afternoons, but it is too soon to tell
what portions of our area will be favored for activity. However,
given the pattern, the southern portions of the area will have
higher chances than the north, but any change in track of the low
could easily alter this.

Once the low passes, the scenario flips with a saturated lower
portion of the airmass in a noticeably cooler west to northwest
flow for a higher probability of more uniformly light showers,
especially if a smaller scale trough tracks along the coast as
some ensemble members suggest. This new low is likely to track
southward with a gradually diminishing probability of showers and
gradually warming temperatures late next week.

MARINE...Updated 200 PM PDT Friday, April 17, 2026...A weak
thermal trough will maintain gusty north winds and steep seas
south of Cape Blanco this afternoon into early Saturday morning.
Low pressure offshore will bring a return of active weather Sunday
into Wednesday, with increasing swell and periods of gusty south
winds. Winds are likely to be strongest from Sunday morning
through Monday evening, with steep seas possible. -Spilde

&&

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

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 2 AM PDT Saturday
     for PZZ356-376.

&&

$$