678
FXUS66 KMFR 050409
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
909 PM PDT Sat Oct 4 2025

...Updated the aviation and marine sections...

.AVIATION...05/00Z TAFs...The remnants of a front have left enough
residual low level moisture for areas of mixed IFR/MVFR ceilings
along the coast north of Cape Blanco (including North Bend), with
areas of VFR ceilings inland. Overnight into Sunday morning, North
Bend and Roseburg will both likely see lower ceilings (IFR/LIFR).
Also, patchy fog could develop and last for a few hours in the early
morning in the valleys/basins of northern California and over the
East Side where it has recently rained, perhaps even at Klamath
Falls But, low-level northeast winds will develop and this may cause
some of these ceilings to erode early Sunday morning. -DW

&&

.MARINE...Updated 800 PM PDT Saturday, October 4, 2025...A thermal
trough along the coast will cause moderate to strong north winds
over the waters tonight into Monday. Winds and seas will be highest
south of Cape Blanco, though all areas will have conditions
hazardous to small craft. The thermal trough will weaken early next
week with winds and seas subsiding from east to west over the waters
on Monday. A brief period of calmer conditions is expected Monday
night into Tuesday, but north winds and steep seas could return for
Wednesday. -Spilde

&&

.PREV DISCUSSION... /Issued 236 PM PDT Sat Oct 4 2025/

DISCUSSION...Despite the minimal returns showing up on radar, surface
observations show a few hundreths being reported along the coast and
into the Umpqua Basin this afternoon. A weak front is moving through
the area in north to northwest flow, but aside from the light
showers previously mentioned, the remainder of the forecast area
will remain dry with increasing sunshine the farther south you go.
High temperatures today will again be around 10 to 15 degrees below
normal across the region. Shower activity should mostly come to an
end later this evening and overnight as offshore flow develops
tonight. We`ll transition to a period of warmer and drier conditions
through as this offshore flow (east to northeasterly winds) develops
tonight, peaking Sunday night but continuing into early Tuesday
morning.

Low level cloud cover will linger across the region tonight into
Sunday morning, primarily in West Side Valleys, but also across
northern Klamath County and much of Lake County. This should keep
temperatures up some across the the Christmas Valley tonight, but we
still expect freezing temperatures each morning through Tuesday,
with even the warmer areas still seeing lows near freezing. On the
coldest morning of this episode, a hard freeze is expected for much
of the East Side on Monday morning. Given the recent cold mornings
and that we`ve reached the time of year when normal low temperatures
average freezing, we`ll forego any additional freeze warnings for
the season. After a cool, cloudy start for many on Sunday morning,
skies will quickly clear under a drying air mass and increasing east
to northeast winds. We`ll see a warming trend west of the Cascades
by about 10 degrees compared to today`s highs, with similar to a few
degrees warmer for the East Side. The Chetco Effect will set up on
Sunday, bringing warm temperatures to the coast with Brookings
forecast to reach into the mid/upper 70s Sunday afternoon.
Meanwhile, West Side Valleys will see highs also reach into the
mid/upper 70s while the East Side hovers in the 55-65 degree range
(still about 10 degrees below normal).

With offshore flow strengthening Sunday night into Monday morning,
skies will remain clear for the whole forecast area. Though there
could be pockets of fog/low clouds in the deeper valleys west of the
Cascades, even the marine layer is likely to be non-existent and
clear skies are expected at the coast. Temperatures will trend
warmer again on Monday by about 5 degrees compared to Sunday`s
values for all areas, so even the East Side will see temperatures
closer to seasonal normals (upper 60s/low 70s). The Chetco Effect
will bring another day of elevated temperatures to the Brookings
area and even areas north of Cape Blanco are forecast to reach into
the upper 70s on Monday. Rinse and repeat for Monday night into
Tuesday, though east to northeast flow will begin to weaken Monday
night. Cooler temperatures are expected at the coast on Tuesday,
with similar values expected over West Side Valleys. Meanwhile,
temperatures trend warmer by about 5 degrees east of the Cascades on
Tuesday.

Wednesday through Saturday...Models continue to show a closed low
developing over the Gulf of Alaska before digging south towards the
area later in the week. Models historically have difficulty with
determining where wobbly, broad, closed upper level troughs will
track, and this trough is no exception. The Wednesday into Thursday
period has the highest probability of being characterized by
increasing high clouds and a southerly flow, with a low, but highest
probability of light showers for the coast. By Friday, day 7, and
even more so for next weekend, an episode of cool, wet weather is an
increasing probability. /BR-y


FIRE WEATHER...Updated 230 PM PDT Saturday, October 4, 2025...A
thermal trough will set up along the coast the rest of this weekend
and this will result in a period of gusty east winds over the upper
slopes and ridges beginning tonight. However, RH recoveries tonight
should be good (80-100%) given the recent moisture/rainfall. Fuels
have also moderated substantially, with all locations in moderate
and/or low fire danger. We do expect things to dry out across the
landscape Sunday-Tuesday with afternoon humidity bottoming out in
the in the 15-25% range. And, with gusty east winds continuing
Sunday night and Monday night over the upper slopes/ridges, weather
conditions may approach critical levels during this time period.
Despite this, we don`t think fuels will return to levels necessary
for RFW. We`ll headline the Fire Weather planning forecast to
enhance the message that it will turn drier into mid next week.
Confidence beyond Wednesday is quite low with many possible
scenarios, though with a slight lean in favor of breezy, cooler
weather Thursday into next weekend with a chance of rain. -Spilde

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory from 5 AM Sunday to 5
     AM PDT Monday for PZZ350-356-370-376.

&&

$$