565
FXUS66 KMFR 301727
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1027 AM PDT Sun Aug 30 2026

...Updated AVIATION discussion for 18Z TAFs...

.KEY MESSAGES...

* Dry weather with seasonable temperatures expected today.

* On Monday, temperatures trend warmer. Gusty southerly to
  southwesterly winds and dry conditions will bring elevated fire
  weather concerns for the Scott and Shasta valleys and areas east
  of the Cascades.

* Tuesday, ahead of an approaching low, expect a chance for
  showers and a slight chance for thunderstorms.

* Wednesday, cold front will bring cool temperatures across the
  area. Rainfall is expected west of the Cascades, with lower
  chances east of the Cascades. Cool conditions and lingering
  showers are expected Thursday and possibly into Friday and
  Saturday.


&&

.DISCUSSION...An upper trough centered to the northeast will
shift eastward today, bringing zonal flow over the region. Expect
near normal temperatures and typical afternoon breezes. A low
gradually moves south Monday nears the coast Monday evening. Ahead
of this low expect a shortwave ridge to develop over inland areas
with temperatures trending warmer. Gusty south to southwest winds
ahead of the low along with dry daytime humidities are likely to
bring critical fire weather conditions to the Scott Valley, Shasta
Valley and areas east of the Cascades. A fire weather watch is in
effect for these conditions.

A trough remains off the coast on Tuesday while a stronger low in
the Gulf of Alaska moves off the coast of British Columbia.
Temperatures trend cooler on Tuesday and increasing moisture
combined with daytime instability will allow some showers to
develop and a slight chance (15-20%) for thunderstorms. This will
mainly affect areas from the Cascades west and into northern
Klamath county. The slight chance for thunderstorms is centered
over western/central Siskiyou county northward into the Siskiyous
and Cascades.  Strong, gusty winds are expected in the Shasta
Valley and east of the Cascades. Humidities may remain low enough
to bring elevated fire weather conditions (due to gusty wind and
low humidities) to portions of the east side. See the fire weather
discussion below for details.

Then, Wednesday into Wednesday night, the low shifts southward and
brings a front into the region. This will bring a fall like
pattern with much cooler temperatures, areas of rainfall and gusty
southwest winds.  Daytime highs could be 10 to 15 degrees below
seasonal norms. Rainfall is most likely from the Cascades west
60-90% chances Wednesday afternoon and Wednesday night. These
chances are lower east of the Cascades, with Klamath Falls having
60% chances of measurable rainfall on Wednesday night while
30-50% chances get into Lake and western Modoc counties.
Significant rain is possible along the coast with the National
Blend of Models forecasting 1.0 to 2 inches of rain across Curry
County and 0.75 to 1.0 in of rain across Coos County and northwest
Douglas County. Rainfall amounts are lower inland with around 0.3
to 0.75 inches in the Umpqua Basin, Illinois Valley, Crater Lake
area and far western Siskiyou County. Rainfall near 0.25 inches
or less is forecast across Jackson County, in the Grants Pass
area, and over northern Klamath county. Elsewhere, expect lighter
amounts (trace to 0.10 inches).

Behind this front, on Thursday, upper trough around a low
pressure system lingers over the area, bringing a cool and showery
pattern to the region. Friday into Saturday, models showing high
variability on the track of this low with some indicating the low
will weaken but remain over the region while others favor it
lifting northward. Overall, expect some lingering chances for
showers and generally cooler than normal temperatures to remain in
place through Saturday.

&&

.AVIATION...30/18Z TAFs...VFR levels under clear skies persist
across northern California and southern Oregon for much of the TAF
period. Northerly winds will pick up along the coast this afternoon,
then ease into the evening. MVFR/IFR ceilings are possible along the
coast early Monday morning, but a slight easterly component to winds
may limit ceiling development. Any coastal ceilings that do develop
look to clear out before Monday afternoon. -TAD

&&

.MARINE...Updated 100 AM PDT Sunday, August 30, 2026...Gusty
winds spread northward today, with steep seas extending into the
waters north of Cape Blanco. Conditions will improve Monday and
Tuesday ahead of midweek to late week active weather and unsettled
seas. As a front moves into the area, gusty south winds and steep
to very steep seas are possible on Wednesday. Winds are expected
to lower Thursday and northwest swell builds into the area.

&&

.FIRE WEATHER...Updated 100 AM PDT Sunday, August 30, 2026...

Today will be a relative lull in activity as a ridge briefly
builds in with warmer temperatures and lower minimum humidities,
but weaker winds. As a trough approaches from the west,
conditions are then likely to reach critical levels Monday in the
Scott and Shasta valleys and east of the Cascades due to gusty
south to southwest winds and dry humidities. A fire weather watch
is in effect for portion of FWZ 280 (Scott Valley) and FWZs 281,
284, 285, and 624.

A trough dominated pattern will follow for the remainder of the
week with a cooling trend and increasing chances for rain. On
Tuesday, a low nears the coast and moisture combined with daytime
instability will allow for some showers to develop, especially
from the Cascades west. There is also a slight chance for
thunderstorms centered along the Cascades and Siskiyous and into
western/central Siskiyou County. Strong, gusty winds are likely
east of the Cascades and in the Shasta Valley. Guidance indicates
gusty winds and low afternoon humidities will approach critical
fire weather conditions across southeastern portions of FWZ 624,
625 and eastern 285.

Then, the pattern trends wetter and cooler as a front moves into
the area on Wednesday and Wednesday night. Rain is likely,
especially from the Cascades west and into northern Klamath and
northern Lake counties. Gusty winds may affect most the area on
Wednesday but expect higher humidities. With a trough over the
area, chances for showers linger on Thursday and possibly into
Friday and Saturday.



&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Fire Weather Watch from Monday afternoon through Monday evening
     for ORZ624.

CA...Fire Weather Watch from Monday afternoon through Monday evening
     for CAZ280-281-284-285.

PACIFIC COASTAL WATERS...Small Craft Advisory until 5 AM PDT Monday
     for PZZ356-376.

     Small Craft Advisory from 11 AM this morning to 5 AM PDT Monday
     for PZZ350-370.

&&

$$