or discuss
Office: MFR
FXUS66 KMFR 011056
AFDMFR
Area Forecast Discussion
National Weather Service Medford OR
256 AM PST Mon Dec 1 2025
.DISCUSSION...A high pressure ridge, centered over the Pacific,
extends across the area. This ridge will remain in place through
late this week. A weak shortwave is forecast to move down the
eastern side of this ridge tonight and into eastern Washington,
northeast Oregon and Idaho on Tuesday. This will bring onshore,
moist flow into northwest portions of the area. The National Blend
of Models continues to indicate chances for light rainfall at the
coast (20-60%) and inland over Douglas County (10-40%). Any
rainfall that occurs would be very light, around a trace to a few
hundreths of an inch. Otherwise, dry weather with seasonable
temperatures is expected across the area through Wednesday.
Overnight and morning valley fog may be the main concern through
mid week, with strong inversions and lingering moisture allowing
for areas of fog each day, especially west of the Cascades.
North to northeasterly winds are expected aloft, bringing some
breezy winds to the ridges today. Additionally, breezy northerly
winds are expected along the coast this afternoon and evening, and
again Tuesday. Inland, winds will increase out of the northwest
on Tuesday with the passage of the shortwave trough. Breezy to
gusty northwest winds (gusts to 15-25 kt) are expected east of
the Cascades on Tuesday.
The shortwave trough will shift southeastward Tuesday night and
Wednesday, with the high pressure ridge strengthening again over
the region. There is high confidence of dry weather across the
area Tuesday night and Wednesday.
Late in the week, ensembles support a more active pattern moving
into the Pacific Northwest as frontal systems move over the ridge
and into the region. This will bring chances for light
precipitation by Friday, then increasing chances for precipitation
Friday night and Saturday. There is more variability in the models
beyond Saturday, with the ECMWF drying out by Sunday and the GFS
staying active through the weekend and into next week. Meteograms
for both models generally support their respective deterministic
patterns, although the ECMWF ensemble has ~20% of its members
showing continuing rainfall. If the GFS outcome holds true,
precipitation amounts and snow levels will be a focus of future
forecasts. We will continue to monitor this period and update as
confidence increases.
&&
.AVIATION...01/06z TAFs...Aside from persistent MVFR stratus in
the Umpqua Basin, and patchy LIFR in the Grants Pass area, VFR
conditions prevail across the region with high level cirrus
streaming overhead. Offshore flow across the area should keep fog
development limited along the coast and east of the
Cascades/Klamath Basin, so VFR conditions are expected to prevail
through the TAF period there. There could be a few hours overnight
for some scattered LIFR conditions at North Bend/Coquille Basin,
but easterly flow should keep this from persisting.
For the Rogue/Illinois/Applegate Valleys and the Umpqua Basin,
IFR/LIFR conditions are likely tonight into Monday morning, then
clear to VFR by 18-21z. High level cloud cover is expected to
continue overnight and this could limit the extent of the fog
development and persistence. VFR conditions are expected to prevail
across northern California through the TAF period. /BR-y
&&
.MARINE...Updated 200 AM PST Monday, December 1, 2025...Breezy to
gusty northerly winds will continue through Wednesday, with gusts
south of Port Orford reaching Small Craft Advisory strength.
Additionally, long period west swell will build into the waters
late today and tonight, then peak on Tuesday (with west swell
building to 8 to 9 feet at 16 seconds and combined seas of 9 to 11
feet). Steep seas are expected across the waters south of Cape
Blanco through at least Wednesday. Seas may also become steep
north of Cape Blanco Tuesday night and Wednesday. Conditions may
briefly improve for Thursday, but the pattern is likely to turn
more active late in the week.
&&
.BEACH HAZARDS/HIGH SURF...Updated 200 AM PST Monday, December
1, 2025...Guidance shows a long period swell arriving Monday,
first arriving at around 2 to 3 ft at 20 to 22 second this
morning. This swell is expected to build to around 7 to 9 ft at 16
to 18 seconds late this afternoon into Tuesday morning with
combined seas of 9 to 11 feet. While seas will be steep, high surf
conditions are not expected along beaches. However, these
conditions will bring a risk for dangerous sneaker waves. If you
have plans to visit the coast on Monday, please be aware of this
sneaker wave potential and consider rescheduling your ventures to
the beaches for another day. These waves can wash over rocks and
jetties and can suddenly knock people off of their feet and sweep
them into the ocean. They can also move logs or other objects
which could crush or trap anyone caught underneath. While sneaker
waves can occur at any time, the greatest risk is on an incoming
tide. Please be aware of the tides if venturing out onto the
beaches. Remember, NEVER turn your back on the ocean!
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Beach Hazards Statement from 7 AM PST this morning through
Tuesday afternoon for ORZ021-022.
CA...None.
PACIFIC COASTAL WATERS...Small Craft Advisory from 10 AM this morning
to 7 AM PST Wednesday for PZZ356.
Small Craft Advisory until 7 AM PST Wednesday for PZZ376.
&&
$$
Office: PQR
FXUS66 KPQR 011043
AFDPQR
Area Forecast Discussion
National Weather Service Portland OR
243 AM PST Mon Dec 1 2025
.SYNOPSIS...High pressure continues over the region today with
mostly dry conditions expected through this evening. A weak front
will bring chances for light rain tonight into Tuesday. Dry again on
Wednesday. Active weather returns as a series of frontal systems
bring increasing chances for rain later Thursday through the
weekend. Seasonable temperatures continue through the week.
&&
.SHORT TERM...Today through Wednesday night...An upper ridge of high
pressure over the region this morning will shift east as a shortwave
trough drops down across the Pacific NW tonight. After a chilly and
frosty start across much of the area today, expect increasing clouds
with afternoon temperatures only warming into the upper 40s through
much of the lowland valleys. Temperatures likely a bit warmer along
the coast thanks to some light offshore flow.
A weak frontal system will push across the area later tonight into
Tuesday. Rainfall accumulations are expected to be minimal as
showers remain relatively shallow as a warmer air mass persists in
the mid-levels. Most locations will only see a few hundredths of an
inch of rain, except along the north coast, and in the higher
terrain influenced by orographic lift, where amounts will vary up to
a quarter inch. There is less than a 10% chance in these areas for
amounts up to a half inch of rainfall.
High pressure rebuilds across the region on Wednesday with dry
weather and seasonable temperatures expected. Increasing moisture in
the mid levels within the north to northwest flow aloft will likely
maintain some sort of cloudiness. /DH
.LONG TERM...Thursday through Sunday...Models and their ensembles
are in good agreement that the upper level ridge remains over the
northeast Pacific on Thursday. But, WPC cluster analysis does
indicate high probability of the ridge breaking down and flattening
out, allowing for more westerly flow into the Pacific NW Friday and
into the weekend. This should allow for frontal systems to bring
increased rainfall and more active weather to the area. Uncertainty
in rainfall amounts remains moderately high, but extreme rainfall
appears very unlikely. For example, the probability for IVT values >
250 kg/m/s from the coast to the foothills is quite high (greater
than 80-90%) both Friday and Saturday, but the probability of IVT
values greater than 500 kg/m/s is very low. Both the GEFS and ECMWF
ensemble means suggest total precipitation amounts of around 2
inches near Astoria through Sunday. The NBM suggests similar amounts
for Friday through Sunday (72-hour period), while the 90th
percentile (10% chance of exceeding) suggests potential for total
rainfall amounts nearing 3 to 4 inches. Still, more beneficial with
minimal impacts expected. Will note that HEFS guidance does show
increasing (but still low) chances for local rivers reaching action
or minor flood stage, with the highest chances for coastal rivers
(up to 5-15%) into early next week. /DH
&&
.AVIATION...An upper level ridge of high pressure will maintain
predominately VFR conditions through at least 06z Tuesday. An
exception to this is patchy stratus across parts of the southern
Willamette Valley, as well as along the lower Columbia River near
KKLS. MVFR CIGs are likely to linger near KEUG through 14-16z this
morning, while LIFR CIGs should stay north of the Portland metro.
Light and variable winds along with mostly clear skies this
morning will allow for cooler temperatures into the lower 30s,
which favors frost development.
By 06z Tuesday, probabilities for MVFR cigs around 3000 ft
increase to near 50% at KAST as a weak front approaches the area.
Light rain showers are likely to develop at KAST shortly after
06z Tuesday.
KPDX AND APPROACHES...VFR conditions expected through this
evening beneath scattered high clouds. There is less than a 10%
chance of IFR stratus approaching the terminal from the north
early this morning. Expect temperatures this morning to drop into
the lower 30s. Expect increasing clouds after 00z as a weak front
approaches from the northwest. Chances for MVFR CIGs increase
after 09z Tuesday. Light and variable winds expected today. /02
&&
.MARINE...With high pressure offshore today, will see north to
northeast winds to around 10 kt, while seas remain around 4 to 6
ft. A weak front traversing the waters tonight into Tuesday will
shift winds to northwest, increasing up to 15-20 kt, while a long
period westerly swell builds seas to around 9 to 10 ft on Tuesday.
Have issued a Small Craft Advisory for the outer coastal waters
north of Cape Foulweather to cover this marginal threat.
Winds and seas ease midweek as high pressure returns. A more
active weather pattern develops late in the week as a series of
frontal systems is expected to moves across the waters from
Thursday into the weekend. There remains a 20-40% chance of seas
rising above 10 ft again Friday into Saturday. /DH
&&
.BEACH HAZARDS...A long-period westerly swell is expected along
the northwestern Oregon and southwestern Washington coasts from
late Monday through Wednesday next week. Wave heights increasing
to 8 to 10 ft on Tuesday may not appear to present a safety risk
to those on area beaches, but these energetic waves will present a
moderate to high risk for sneaker waves, waves which can run
significantly farther up a beach than normal, including over rocks
and jetties. In addition, a period of perigean spring or "king"
tides means these waves will have an even easier time reaching
high up onto beaches, limiting the areas which may be safe from
wave action.
A Beach Hazards Statement has therefore been issued from 7 AM
Tuesday to 10 PM Wednesday. Sneaker waves can create potentially
life-threatening conditions in the surf zone when beachgoers can
be unexpectedly knocked off their feet and pulled out into cold
ocean waters. Caution should be used when in or near the water,
and those with children should be especially watchful. Never turn
your back on the ocean, and be sure to keep an eye on the waves.
Those participating in razor clam digs should additionally
exercise caution. -36
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory from 4 AM to 10 PM PST Tuesday for PZZ271-
272.
&&
$$
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Office: PDT
FXUS66 KPDT 011150
AFDPDT
Area Forecast Discussion
National Weather Service Pendleton OR
350 AM PST Mon Dec 1 2025
.DISCUSSION...An upper-level ridge of high pressure is in place
over the Pacific Northwest early this morning. Aside from chilly
temperatures ranging from the upper single digits to upper 20s and
some areas of low stratus and patchy fog, the remainder of the
night and morning is expected to be uneventful.
Later this morning through afternoon, the first in a series of
shortwaves embedded within northwesterly flow aloft will track
over the forecast area. While this first shortwave, currently
visible in water vapor imagery extending southwest from the
northwest end of Vancouver Island into the Pacific, will be weak,
there is a 10-30 percent chance of light precipitation with the
wave.
The main event, a stronger shortwave, is advertised by ensemble
NWP guidance to arrive this evening, subsequently crossing
overhead tonight through Tuesday night before exiting to the south
and east through Wednesday morning. While upper-level dynamics
don't look quite as good with this shortwave compared to the
compact closed low that brought low-elevation snowfall to the
region Friday evening, deep northwesterly flow should facilitate
orographic precipitation, especially over the northern Blue
Mountains and other favored areas of northeast Oregon. Was
previously expecting a better moisture tap with this system;
however, that no longer appears to be the case as forecast
soundings from the HREF and REFS show PWATs of 0.3-0.6 of an inch
again. Snow chances are low across the Blue Mountain foothills
and eastern half of the Columbia Basin (10-30 percent chance of
measurable snow per NBM guidance), but better chances (50-70
percent) of at least 4 inches of snow are shown for the northern
Blue Mountains. Advisory-level snowfall is possible (20-45 percent
chance) across the northern Blue Mountains, but confidence was
too low to issue any winter headlines at this time. Part of what
is driving uncertainty in the amount of snowfall is the vertical
depth of moisture, specifically whether or not saturation will
extend into or through the dendritic growth zone (DGZ). While a
couple members of the HREF and REFS do exhibit saturation through
the DGZ, most only extend partially into the zone (or not at all)
which would limit snowfall efficiency.
Ensemble guidance is still suggesting some locally breezy
westerly winds through the Cascades gaps on Tuesday.
Mostly dry conditions are expected (70-90 percent chance)
Wednesday into Thursday morning as upper-level ridging returns to
the Pacific Northwest.
By the end of the week, ensemble solutions begin to diverge with
regard to pattern details, but a transition to a more zonal
upper-level pattern is present among all ensemble clusters
beginning Friday and extending through Sunday. As far as tangible
weather, this would result in warmer, wetter, breezier conditions.
Of note, EFI values ranging from 0.5-0.8 across the Columbia
Plateau are pointing to decent ensemble agreement in windy
conditions relative to model climatology from 00Z Saturday to 00Z
Sunday. Moreover, NBM probabilistic guidance suggests low-medium
(20-60 percent) chances of advisory-level wind gusts Friday
through Sunday, and there is low potential (10-20 percent chance) for
a high-end wind event late Friday and Saturday across the region.
&&
.AVIATION...12Z TAFs...VFR conditions prevail for the entire
region, except for the PSC site. Low stratus is sloshing in and
out of the airport. Was split on putting a prevailing line for
LIFR or a TEMPO but went ahead and put it in a TEMPO through 16Z.
Else wise, VFR conditions will continue throughout the region.
Have some possible showers passing through the central Basin
(PDT/ALW/PSC) at the tail end of the period, but wasn't confident
on any widespread impacts, so kept them tapered at 30% at each
site. /95
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 37 29 40 27 / 10 40 70 10
ALW 36 31 38 29 / 20 50 80 20
PSC 36 27 40 25 / 10 30 30 0
YKM 38 25 44 23 / 10 20 10 0
HRI 37 28 41 27 / 10 30 50 0
ELN 37 26 43 22 / 20 30 10 0
RDM 48 27 46 21 / 10 10 10 0
LGD 42 32 41 26 / 10 50 90 20
GCD 46 31 43 27 / 10 30 60 10
DLS 42 35 50 34 / 20 20 20 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
&&
$$
DISCUSSION...86
AVIATION...95
