758
FXUS66 KMFR 071229
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
529 AM PDT Tue Oct 7 2025

.DISCUSSION...The forecast separates into 3 portions. First, a
continuation of warm and dry conditions under both high pressure
today, and a transition day tomorrow with an approaching broad
closed low. The low will be over Alaska today and move to near
Vancouver Island on Wednesday. Temperatures today will resemble
those of yesterday, then they will trend several degrees cooler
for Wednesday. This includes a marine push tonight into Wednesday
morning with overcast skies for Coos and western/northern Douglas
counties. Breezy easterly winds will continue over the higher
terrain from the Coast Range to the Cascades this morning, but
winds will be weaker elsewhere. Breezy southwest winds are
expected Wednesday afternoon in northern California and from the
Cascades eastward.

Second, while the specifics are still in question, confidence is
high in the evolution of the features that will drive our weather
Wednesday night through Saturday night. It will be an active
pattern driven by the slow moving trough, resulting in: cooler
temperatures, rain chances, and periods of gusty winds. The
probability of rain will be highest on Friday into Friday night.
The uncertainty in the specifics arises from a wide range of
solutions regarding the vertical moisture profile, and thus the precipitation
amounts. The 06Z GFS is among those showing a slow moistening of
the lower and mid levels of the air mass. In such an instance,
virga may be common on Thursday with the best chance for light,
measureable rainfall over the Cascades. By Friday, a stronger
shortwave is likely to move around the base of the trough into our
region. The highest precipitation amounts and rain chances would
be on and near south and southwest facing slopes on the west side.
This includes Curry, Josephine, and western and southern Siskiyou
counties. The highest probability is that it would be late Friday
afternoon or Friday evening before the probability of
precipitation reaches a peak on the east side. Snow levels look to
be around 6500 to 7500 feet, still above all but the back country.
Please stay tuned for further details as this event draws nearer.

By Saturday, the next front is expected to arrive from the
northwest, on the back side of the trough. A majority of ensemble
members depict that this front will be focused upon Washington and
northern Oregon, with the highest probability of showers in our
area for our northern portions of Coos and Douglas counties,
possibly into northern Klamath County. Elsewhere, clouds and very
cool temperatures look to be the main results.

Third, model solutions then significantly diverge for early next
week. The differences are mainly shown as disagreement in the
extent to which the longwave trough axis remains over the west
coast or shifts toward the Rockies. Secondarily, the extent to
which weak ridging could nudge into our area between the parade of
troughs in a continued cooler than normal, north-northwest flow
aloft. The blended model solution indicates slight chance to
chance probabilities of light rain. As a whole, the ECMWF
ensemble suite leans more toward a cooler and wetter, more
progressive solution than the GFS. Historical bias would suggest
leaning toward the ECMWF. -DW

&&

.AVIATION...07/12Z TAFs...VFR levels with clear skies and
visibilities look to continue into this evening. Breezy easterly
winds over the Cascades and west side terrain will ease by this
afternoon. IFR ceilings are expected to develop across the coastal
waters from Cape Blanco northward late this evening, and spread into
the Coquille, Camas, and lower Umpqua valleys overnight into
Wednesday morning. Meantime, skies will remain clear elsewhere. -DW

&&

.MARINE...Updated 200 AM PDT Tuesday, October 7, 2025...A brief
period of calmer conditions is expected through this afternoon as
winds briefly ease. Gusty north winds and steep seas are expected to
return to all areas early this evening through Wednesday night
before winds weaken and turn southerly Thursday morning. Conditions
will be borderline in terms of advisory level winds and seas, but
enough so into the advisory category to support a Small Craft
Advisory this evening through Wednesday night. The passage of a weak
front is expected to bring an increase of northwest swell dominated
seas early Thursday. With the weakening of north winds, and seas
transitioning to swell dominated, seas will become less steep and
less hazardous to small craft.

South winds increase Thursday night and may reach the low end of
advisory strength through Friday night as low pressure lingers
offshore. The low is expected to move inland over the weekend with
marine winds becoming northerly and increasing into early next week.
These north winds are likely to be strongest south of Cape Blanco,
and may reach advisory strength. /BR-y

&&

.FIRE WEATHER...Updated 200 PM PDT Monday, October 5,
2025...Offshore (east to northeast) flow will persist into Tuesday
morning. The Rogue Valley in particular, is expected to see gusty
southeast winds of 10 mph with gusts to 20 mph through Tuesday
morning, except for the current uptick where winds are more along
the lines of 20 mph with gusts to 30 mph. Daytime humidities will
bottom out in the 15-25% range through Tuesday, possibly into
Wednesday. Ridge top humidity recoveries will be poorest Tuesday
morning, though with weaker easterly wind gusts commonly expected at
15 to 20 mph, so there is less concern for critical conditions
tonight into Tuesday. Given that fuels have moderated substantially
due to recent wet and cool weather, and many locations have lowered
the fire danger to moderate or better, we`ll maintain a headline in
the Fire Weather Planning forecast for this easterly flow event.

Weak onshore flow returns later on Tuesday, and daytime humidities
will trend somewhat higher with improved recoveries expected Tuesday
night. Major improvement, however, will be limited to the coast
until Wednesday night. Gusty south to southwest winds return to the
region starting Wednesday as an upper level system moves southward
just offshore, but daytime humidities will still be trending higher.
This is especially so for northern California and south central
Oregon where gusts of 30 mph possible will be possible. There`s
uncertainty on how far offshore this system traverses, but there
could be some light rain along the coast as early as Thursday. While
uncertainty in the details remains, confidence is increasing for a
return to cooler and wetter weather late in the week and into the
weekend. /BR-y

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory from 5 PM this
     afternoon to 5 AM PDT Thursday for PZZ350-356-370-376.

&&

$$