or discuss
Office: MFR
FXUS66 KMFR 041203
AFDMFR
Area Forecast Discussion
National Weather Service Medford OR
403 AM PST Thu Dec 4 2025
.DISCUSSION...Updated Aviation Discussion.
&&
.AVIATION...04/12z TAFs...LIFR/IFR in fog will persist in valleys
west of the Southern Oregon Cascades this morning, lifting to VFR
in the late morning. A weak front will move into the area today,
with periods of light rain expected along the coast, into the Umpqua
and southern Oregon Cascades this afternoon and tonight.
Low clouds will spread inland late this afternoon and this evening,
with MVFR and IFR developing along the coast inland to the Cascades.
From the southern Oregon Cascades west, ceilings are expected to
lower overnight to IFR/LIFR with IFR visibilities. Mountain
obscurations are likely. Areas of MVFR ceilings may spread east of
the Cascades and into portions of northern California late Thursday
night.
&&
.PREV DISCUSSION... /Issued 313 AM PST Thu Dec 4 2025/
DISCUSSION...
Key Points:
* A warm front moving over the ridge will bring chances for light
rain to northern portions of the area today, with light rain
likely Friday as a cold front moves inland.
* Breezy to gusty winds are expected across the mountains and
east of the Cascades Friday afternoon into Friday night.
* Expect continuing chances for light precipitation this weekend.
Then additional rain moves into the area Monday into Tuesday as
another front moves into the region.
* King Tides are this weekend, but not expecting impacts/hazards.
* Signs point towards a potential for more significant and active
weather Dec 10-12th
- Heavy rain (west of Cascades) and heavy snow (Cascades)
Today through Sunday:
The upper level ridge over the Pacific will flatten as low
centered over the Aleutian Islands sends a shortwave trough and
front into the region. A warm front will gradually move into the
Pacific Northwest today. This front will be centered north of the
area, but will bring chances for light rain to portions of
southwest Oregon, mainly along the coast, Douglas County and into
northern Klamath and Lake counties. Then as a cold front
approaches early Friday and gradually moves inland Friday and
Friday night, this will bring increasing chances for light
precipitation across the area. Models and guidance indicate breezy
to gusty winds over the mountains and east of the Cascades on
Friday as well. This may bring some local impacts to higher
mountains with gusts of 30 to 45 mph possible late Friday. Snow
levels will be high around 7000+ feet through Friday, lowering
behind the front to 5500 to 6500 feet Friday night across
southwest Oregon.
On Saturday, the National Blend of Models supports lingering
chances for light showers, with best chances (50-80%) along the
coast, into Douglas County and the southern Oregon Cascades. Snow
levels may drop to 5000 to 6000 feet across southwest Oregon and
6500 to 7000 feet across northern California on Saturday. So, this
may result a dusting of snow to higher mountains in the Southern
Oregon Cascades.
This pattern continues into Sunday. Another shortwave trough and
frontal system are expected to move into the region from the
northwest on Sunday and Sunday night, bringing additional chances
for generally light precipitation. Snow levels are expected to
range between 6000 to 7000 feet during the day Sunday and into
Sunday night.
Next week:
Another, stronger front is forecast to move into the region early
next week. Models and ensembles show this system moving inland
over the Pacific Northwest Monday and Tuesday. Deterministic
models and ensembles show highest chances for moderate to heavy
precipitation staying north of the area during this period, with
generally light precipitation affecting southwest Oregon and low
chances for precipitation across northern California. Snow levels
are high during this period, so expect precipitation to fall
mainly as rain.
Looking further ahead, cluster analysis for 500mb anomalies is
still split on a potential trough in the area Dec 10th-12th. This
could lead to a slight risk of both heavy rainfall and heavy
snowfall, but given the split (trough vs ridge) there is a lot of
uncertainty. Additionally, this is pretty far out in the future,
and a lot could change, but we are watching this time period for
potential active weather. We will continue to monitor and refine
the details in the coming days. Snow pack is really low for this
time of year. The average (1991-2020) snow depth for today (Dec
3rd) at Crater Lake is is normally 28.0", but we are sitting at
zero. It will likely take a few systems to get back to normal, but
this potential system next week would be a good start.
MARINE...Updated 200 AM PST Thursday, December 4,
2025...Advisory level north winds will maintain steep seas south
of Cape Blanco into this afternoon. Long period, swell dominated
seas will persist north of Cape Blanco. Winds shift to west
Thursday evening then southwest on Friday, and the resulting wind
seas will combine with ongoing swell to produce steep seas. Then
steep, west seas are expected on Saturday. Gusty south winds and
additional steep seas may develop Saturday night into Sunday.
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.
CA...None.
PACIFIC COASTAL WATERS...Small Craft Advisory from 4 PM this
afternoon to 4 PM PST Saturday for PZZ350-370.
Small Craft Advisory until 4 PM PST Saturday for PZZ356-376.
&&
$$
Office: PQR
FXUS66 KPQR 041209
AFDPQR
Area Forecast Discussion
National Weather Service Portland OR
410 AM PST Thu Dec 4 2025
.SYNOPSIS...A series of fronts will bring a period of wet weather
Thursday through at least the middle of next week across southwest
Washington and northwest Oregon. Ensemble guidance suggests a
potentially impactful atmospheric river event next Monday into
midweek, though uncertainty is very high.
&&
.DISCUSSION...Today through Wednesday...December is, on average, the
wettest month of the year here in northwest Oregon and southwest
Washington. So it should not come as a big surprise that the stretch
of mostly dry weather to start the month would not last too long.
Expect varying amounts of rainfall each day through this next week,
with potential for heavier rain early next week, as a series of
weather systems produces multiple rounds of widespread rain across
the Pacific Northwest.
An upper level ridge of high pressure remains over the northeast
Pacific today, but eventually shifts southeast, flattens, and allows
for more zonal flow into the region. A warm front associated with
this initial system will stall near the coast today, spreading light
rain across much of the area. Due to the northwest orientaion of
winds, the Willamette Valley will likely be rain shadowed and see
lower rain accumulations through this evening. The flow turns a bit
more westerly on Friday, and an associated plume of deeper moisture
will attend a cold front approaching the coast. IVT values are
expected to peak around 500-700 kg/m/s, bringing a second round of
widespread, heavier rain through Friday afternoon. Breezy southwest
winds will also be possible with the frontal passage on Friday, with
gusts most likely peaking around 20-30 mph.
Showers expected to linger through Saturday as onshore flow
continues. Then, another frontal system moves through the area on
Sunday. Ensembles indicate IVT values could peak around 300-500
kg/m/s with this frontal system which would produce another round of
widespread rainfall. Total rainfall amounts Thursday through Sunday
are most likely to be around 1.0-2.0 inches for interior lowlands,
2.0-4.0 inches at the coast, and 3.0-6.0 inches for the Coast Range
and Cascades. But, there remains a fair amount of uncertainty in
both the low and high end potential. Impacts are not expected with
rain amounts through Sunday, unless rain rates exceed 0.2-0.3 inches
for multiple hours over certain watersheds leading to rivers that
are prone to flooding quickly, such as the Grays at Rosburg and
Willapa River. This will be something to monitor during heaviest
periods of rain.
The main period of concern for the forecast period is next week as
ensemble guidance continues to indicate the potential for an
impactful atmospheric river event Monday through Wednesday.
Significant uncertainty still remains in the length of elevated IVT
values, location of the moisture along the WA and OR coast, and
exact peak of IVT values (the 00z GEFS mean is around 650 kg/m/s
with +1 standard deviation around 800 kg/m/s, and the 12z Euro EPS
mean is around 750 kg/m/s with +1 standard deviation around 850
kg/m/s). These factors have jumped around between forecast runs over
the past 24 hours and will likely continue to fluctuate until we get
closer to the event. There is the potential that this ends up being
another moderate atmospheric river event, similar to the preceding
events. If this is the case, impacts are likely to be minimal once
again. However, if a strong to extreme atmospheric river event
materializes, there is the potential for widespread river flooding
and/or wind damage or landslides as soils will already be saturated
and river levels higher from the rain from the 4 days prior.
The main period for river flood concerns is Tuesday into Wednesday
as it takes time after rain begins for rivers to rise. HEFS guidance
indicates a 10-30% chance of rivers reaching Minor flooding for
Coast Range and Coastal rivers and 5-20% chance for Willamette River
tributaries, mainly focused on Tuesday into Wednesday, possibly
beyond depending on the rain forecast and/or response times of the
rivers. Of note, HEFS guidance also indicates a 8-15% chance of
exceeding Major flood stage at rivers such as the Nasselle, Willapa,
and Wilson near Tillamook.
Additionally, there are signals for breezy winds with the frontal
passage, although the ensemble spread remains very wide leading to
low certainty. If winds do end up even around 30-40 mph, saturated
soils could cause some localized impacts due to downed trees. Keep
an eye on this forecast, especially if you live in flood prone
regions. DH/03
&&
.AVIATION...Moist, northwesterly flow aloft will push a front
across the area today. Light rain has already begun at the coast,
with mid-level clouds maintaining VFR conditions through at least
12z. Inland, LIFR to low-end MVFR stratus is expected to persist
through at least 14-16z. As rain spreads inland, CIGs are likely
to lift to more widespread MVFR. However, there is about a 40-50%
chance that IFR conditions persist bit longer through 18-20z,
especially across the central and southern Willamette Valley.
Conditions at the coast are expected to trend downward toward MVFR
by 14z Thu near KAST and by 18z near KONP. Conditions are expected
to further deteriorate to IFR behind the frontal passage. Light
winds will increase out of the south to southeast at around 5-10
kt.
KPDX AND APPROACHES...IFR to low-end MVFR stratus expected to
persist through much of the day. Light rain expected to begin by
14-15z Thu as a front pushes across the area. South to southeast
winds increasing to around 4-6 kt today. /02
&&
.MARINE...Active weather returns as winds turn southerly this
morning ahead of the first in a series of fronts. Winds are
expected to increase to around 15-20 kt later this morning, with
gusts up to 25 kt across the coastal waters north of Cape Falcon
through early afternoon. Winds turn westerly behind the frontal
passage, lingering around 10-15 kt through tonight. West to
southwest winds then gradually increase on Friday to around 20-30
kt as the next front moves through. Have issued Small Craft
Advisories to account for these increased winds, today for the
northern zones, and on Friday for all coastal marine zones. Seas
around 5 to 6 ft today are expected to increase later Friday as a
northwest swell pushes into the waters through Saturday. Wave
heights likely build into the lower teens by Saturday morning,
while there is around a 30% chance that seas exceed 15 ft.
The parade of fronts continue through the weekend and into early
next week. There is around a 30-40% of wind gusts reaching 35 kt
on Sunday, while chances for Gales is higher (50-60%) later
Monday. Seas are likely to subside back under 10 ft by Sunday,
before building again Monday. /DH
&&
.BEACH HAZARDS...There is a Coastal Flood Advisory for minor
tidal overflow flooding during high tide from 9 AM to 3 PM
Thursday and Friday for the South Washington Coast and the Clatsop
County Coast in Oregon. Minor flooding up to 1 foot above ground
level is possible during high tide in low lying areas near bays,
sloughs, and the low reaches of the coastal rivers. Coastal
residents in the warned area should remain alert for rising water
and take appropriate action to protect life and property. Remain
out of the water to avoid hazardous swimming conditions. -10
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Coastal Flood Advisory from 9 AM this morning to 3 PM PST this
afternoon for ORZ101.
Coastal Flood Advisory from 9 AM to 3 PM PST Friday for ORZ101.
WA...Coastal Flood Advisory from 9 AM this morning to 3 PM PST this
afternoon for WAZ201.
Coastal Flood Advisory from 9 AM to 3 PM PST Friday for WAZ201.
PZ...Small Craft Advisory from 2 PM this afternoon to 6 PM PST this
evening for PZZ210.
Small Craft Advisory from 8 AM this morning to 2 PM PST this
afternoon for PZZ251-271.
Small Craft Advisory from 4 AM Friday to 4 AM PST Saturday for
PZZ251>253-271>273.
&&
$$
www.weather.gov/portland
Interact with us via social media:
www.facebook.com/NWSPortland
x.com/NWSPortland
Office: PDT
FXUS66 KPDT 041135
AFDPDT
Area Forecast Discussion
National Weather Service Pendleton OR
335 AM PST Thu Dec 4 2025
.DISCUSSION...Fog still lingers throughout parts of the Foothills
of the Blues and Kittitas Valley through the rest of the morning.
Precaution should be given in areas of very dense fog and freezing
fog. Even given the stratus cloud cover, temperatures will
efficiently cool enough, thanks to light winds, to bring
saturation in many areas, especially the lower valleys, plumes of
fog through the night. We'll continue to see temperatures drop
region wide to below freezing, with lower valleys have a bit
shorter on the confidence side that they'll drop below freezing
and instead hover around the low to mid 30s (40-60% chance for
Valleys staying above freezing, and >85% chance for higher
elevations dropping below freezing). Otherwise, upper level dry
northwest winds will keep conditions dry for the rest of the
night. Unsettled weather continues later in the late morning hours
to early afternoon when a trough deepens in central Canada,
allowing shortwaves to form valley rain and snow/wintry mix in the
higher elevations.
We'll have a constant stream of instability with surface southwest
flow, allowing a continuous stream of wetter/warmer weather
through the beginning of next week. Heaviest QPF amounts will be
located in the mountains, with three day totaling up to 3 inches
in the highest elevations (50-70 percent chance) with the lower
elevations that include the Basin, Central Oregon, and the
Kittitas Valleys seeing up to a quarter of an inch of rain, more
so than where the heaviest rain bands occur (40-60 percent
chance). A warm trend will begin on Friday with high temperatures
rising to low to mid 50s and continue on through next week as
well. This will cause some hydro and river level concerns going
through Wednesday with the snow falling between now and then,
although guidance at this time does not have some rivers going
beyond 'Action' stage, it is something to keep an eye for the next
couple of days.
Breezy to windy conditions will be observed with the upcoming
system, with the strongest winds occurring between Friday night
and Saturday morning. Parts of the Columbia Basin, Foothills, and
other lower elevation areas will see gusts up to 30 to 40 mph for
much of the time. NBM advertising 40 to 60 percent chances of wind
advisory conditions over the weekend, with 10 to 30 percent
chances of gusts 57 mph or greater. No wind highlights expected
yet, but confidence is increasing slightly for Wind Advisory
thresholds, the question will be if they mix down enough to the
surface to exceed advisory thresholds.
&&
.AVIATION...06Z TAFs...Thanks to the low stratus layer, this will
drop KDLS/KPSC to MVFR with KYKM at IFR and KPDT/KALW to LIFR
conditions. KDLS/KPSC may briefly see patchy fog overnight into
early Thursday morning (35% confidence), but dense fog could
redevelop for KYKM/KALW while continuing for KPDT thus dropping
VSBYs to 1/2sm or less. The fog should then dissipate around 12Z
for KDLS/KPSC and later in the afternoon for KYKM/KALW. KPDT may
have lingering fog/mist through the day Thursday (40-50%
confidence). In addition to the fog and low cloud decks, a weak
system will begin approaching early Thursday morning with light
rain starting KDLS first before other sites. KRDM/KBDN will be VFR
with light rain Thursday morning until MVFR conditions return
early Thursday evening when low clouds redevelop. Winds will
remain less than 10kts. Feaster/97
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 42 37 54 41 / 90 80 90 50
ALW 41 38 51 42 / 90 90 100 70
PSC 40 33 53 41 / 80 70 70 20
YKM 41 30 51 39 / 50 50 70 50
HRI 41 36 55 43 / 90 70 80 30
ELN 41 33 46 35 / 60 60 80 60
RDM 46 35 56 34 / 50 50 70 30
LGD 40 35 49 39 / 90 90 100 80
GCD 42 37 48 36 / 80 90 90 50
DLS 46 42 56 47 / 80 80 90 80
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Dense Fog Advisory until 11 AM PST this morning for ORZ507.
WA...Dense Fog Advisory until 11 AM PST this morning for WAZ029.
Freezing Fog Advisory until 11 AM PST this morning for WAZ026-
027.
&&
$$
SHORT TERM...95
LONG TERM....95
AVIATION...97
FXUS66 KPDT 041149
AFDPDT
Area Forecast Discussion
National Weather Service Pendleton OR
349 AM PST Thu Dec 4 2025
.Updated for Aviation...
DISCUSSION...Fog still lingers throughout parts of the Foothills
of the Blues and Kittitas Valley through the rest of the morning.
Precaution should be given in areas of very dense fog and freezing
fog. Even given the stratus cloud cover, temperatures will
efficiently cool enough, thanks to light winds, to bring
saturation in many areas, especially the lower valleys, plumes of
fog through the night. We'll continue to see temperatures drop
region wide to below freezing, with lower valleys have a bit
shorter on the confidence side that they'll drop below freezing
and instead hover around the low to mid 30s (40-60% chance for
Valleys staying above freezing, and >85% chance for higher
elevations dropping below freezing). Otherwise, upper level dry
northwest winds will keep conditions dry for the rest of the
night. Unsettled weather continues later in the late morning hours
to early afternoon when a trough deepens in central Canada,
allowing shortwaves to form valley rain and snow/wintry mix in the
higher elevations.
We'll have a constant stream of instability with surface southwest
flow, allowing a continuous stream of wetter/warmer weather
through the beginning of next week. Heaviest QPF amounts will be
located in the mountains, with three day totaling up to 3 inches
in the highest elevations (50-70 percent chance) with the lower
elevations that include the Basin, Central Oregon, and the
Kittitas Valleys seeing up to a quarter of an inch of rain, more
so than where the heaviest rain bands occur (40-60 percent
chance). A warm trend will begin on Friday with high temperatures
rising to low to mid 50s and continue on through next week as
well. This will cause some hydro and river level concerns going
through Wednesday with the snow falling between now and then,
although guidance at this time does not have some rivers going
beyond 'Action' stage, it is something to keep an eye for the next
couple of days.
Breezy to windy conditions will be observed with the upcoming
system, with the strongest winds occurring between Friday night
and Saturday morning. Parts of the Columbia Basin, Foothills, and
other lower elevation areas will see gusts up to 30 to 40 mph for
much of the time. NBM advertising 40 to 60 percent chances of wind
advisory conditions over the weekend, with 10 to 30 percent
chances of gusts 57 mph or greater. No wind highlights expected
yet, but confidence is increasing slightly for Wind Advisory
thresholds, the question will be if they mix down enough to the
surface to exceed advisory thresholds.
AVIATION...12Z TAFS...Conditions range from VFR to LIFR early this
morning. Both ALW, PDT and YKM are LIFR in fog and stratus once
again, while BDN and RDM are VFR, with the other sites mostly
MVFR. Expect slow improvement (if any) at PDT and ALW.
RA is expected to overspread the region later this morning and
then will continue through the afternoon and into the evening.
Depending on location additional RA is anticipated overnight. With
the RA will come more reduced CIGS/VSBYS and even BDN and RDM will
have MVFR this evening and overnight.
Winds are expected to remain light.
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 42 37 54 41 / 90 80 90 50
ALW 41 38 51 42 / 90 90 100 70
PSC 40 33 53 41 / 80 70 70 20
YKM 41 30 51 39 / 50 50 70 50
HRI 41 36 55 43 / 90 70 80 30
ELN 41 33 46 35 / 60 60 80 60
RDM 46 35 56 34 / 50 50 70 30
LGD 40 35 49 39 / 90 90 100 80
GCD 42 37 48 36 / 80 90 90 50
DLS 46 42 56 47 / 80 80 90 80
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Dense Fog Advisory until 11 AM PST this morning for ORZ507.
WA...Dense Fog Advisory until 11 AM PST this morning for WAZ029.
Freezing Fog Advisory until 11 AM PST this morning for WAZ026-
027.
&&
$$
SHORT TERM...95
LONG TERM....95
AVIATION...77
