Heavy Snow in Washington, February 15 to 17, 2025

Area Forecast Discussion
National Weather Service Portland OR
413 AM PST Sat Feb 15 2025

.SYNOPSIS...A frontal system arrives late this afternoon,
returning widespread rain and snow in the Cascades through
Sunday. The Upper Hood River Valley will continue to see winter
weather impacts Saturday night into Sunday morning, mainly from
snow and/or freezing rain. Expect more milder temperatures early
next week, with another weather system arriving mid-week.

&&

.SHORT TERM...Now through Monday Night...A low pressure system
over the NE Pacific will support lowland rain and mountain snow
across the Pacific Northwest this weekend. As of 3 AM PST, radar
and satellite imagery depicts the associated warm front
approaching SW Washington and far NW Oregon. High clouds are
beginning to filter in from this system, which will help keep
temperatures above freezing (32F) across the lowlands as well as
prevent additional fog development. Fog already formed within
the Tualatin Valley and parts of the west Central Willamette
Valley earlier in the night, which will likely stick around
through mid-morning.

As the aforementioned warm front lifts this morning over far NW
Oregon and SW Washington, we'll see light rain and light
mountain snow, mainly north of Tillamook/Yamhill/Clackamas
counties. Areas southward remain mostly dry through the early
afternoon. By 3-5 PM Saturday, the trailing cold front will
push through, bringing more widespread rain and mountain snow to
the area through Sunday. Precipitation will begin along the
coast and gradually spread inland through the evening. 24 hour
rainfall amounts ending 4 PM Sunday are forecast around 0.70-1
inch along the coast and 0.40-0.60 inch for interior lowland
valleys. Between Saturday afternoon and Monday morning, the
Cascades could receive up to 20-22 inches of total snow from
this system, with a 5-15% chance of 2 feet or more at pass-
level. Forecast snow amounts have increased from the previous
forecast package as forecast QPF amounts are now higher.
Therefore, the previous Winter Weather Advisories in the
Cascades have been upgraded to Winter Storm Warnings. Those
traveling through the Cascades should prepare for winter weather
and refer to ODOT/WSDOT for the latest road conditions and
restrictions.

Another area of concern during this system will be central
Columbia River Gorge (east of Cascade Locks) and the Upper Hood
River Valley. Surface temperatures tonight into Sunday in the
Upper Hood River Valley are forecast to fall below freezing,
which would support another round of wintry precipitation.
Confidence is high in the occurrence of winter precipitation,
but only moderate on precipitation type. Latest guidance
suggests periods of both snow and/or freezing rain for the Upper
Hood River Valley as temperatures aloft fluctuate between
freezing and just above freezing. The latest HREF indicates a
60-70% chance of at least 1 inch of snow by then and a 50-70%
chance of at least a glaze of freezing rain (mainly above 1000
ft in the Upper Hood River Valley). The Winter Weather Advisory
for the Upper Hood River Valley remains in effect from 4 PM
Saturday to 1 PM, with the bulk of the winter precip falling
between 10 PM Saturday and 10 AM Sunday. There is a little more
uncertainty in winter precipitation for the central Columbia
River Gorge as model guidance indicates low temperatures will
hover more or less around 32F. Decided to trend slightly below
freezing for Sunday morning lows in the Gorge as a light
easterly wind could keep things cooler. For now, the forecast
calls for around a trace to 0.5 inch of snow in the Gorge.

Showers continue into Monday, all rain except for over the
Cascades as temperatures moderate even more. Low temperatures
Monday morning are forecast to be firmly above freezing for most
locations west of the Cascades and even most of the Upper Hood
River Valley. Daytime temperatures Monday are slated to peak
around 50 degrees for the lowlands as well.      -Alviz/HEC

&&

.LONG TERM...Tuesday through Friday...By Tuesday, ensemble
guidance is in high agreement in a quick ridge breezing over the
PacNW in between weather systems. Mostly dry weather is
expected except for a few showers over the Cascades and Coast
Range. Temperatures also continue to warm with lowland high
temperatures in the low to mid 50s and overnight temperatures
only dropping to the 40s.

Ensemble guidance suggests a quick-hitting weather system will
bring additional widespread precipitation to the region late
Tuesday through Wednesday. Once again rain is expected for most
locations west of the Cascades, including the lowlands, but snow
is possible once again in the Upper Hood River Valley and
central Columbia River Gorge. There is lower confidence in
specifics at this time on snow probabilities and amounts, but a
rain/snow mix is possible during the warmer daytime hours with
better chances of snow in the colder overnight and early morning
hours. Snow is also likely to return over the Cascades. No
significant impacts are expected with this system at this time,
but keep an eye on the forecast as details change.   -HEC/Alviz

&&

.AVIATION...A weak frontal system is moving over the region
pushing a high level clouds inland. In areas under clear pockets,
increased radiational cooling has caused fog to form. This is
mostly occurring in areas that are most commonly impacted by fog
like KHIO and KMMV. Some other rural terminals are experiencing
patchier fog and some reduced IFR VIS. This will continue to be
the trend through the night and dissipate as early as 14Z Sat, and
as late as 17Z. As the front makes landfall, showers are
expected. Due to the warmth of the airmass, precipitation will
generally be rain and no freezing is expected aside from in the
Columbia River Gorge. In the early stages of the frontal passage,
especially in the northern Willamette Valley, light showers
falling on exposed surfaces could temporarily freeze until daytime
warming takes hold.

In the post frontal environment, VFR conditions will return for
inland terminals, with clouds hovering around 4000 ft MSL. This
period of improved conditions though will be short lived as a much
stronger front arrives around 05Z Sunday. This front will bring
low end MVFR CIGS and VIS. Chances increase to around 60% for IFR
CIGS around 12Z Sunday along the coast, and around KKLS.
Widespread precipitation expected.

PDX AND APPROACHES...Low end MVFR CIGS and VIS due to a
combination of a weak frontal band, precipitation, and radiational
cooling in cloud breaks. Periods of mist and very light showers
with the front. While temperatures are above freezing, exposed
conductive surfaces may be cool enough for some areas of very
light ice accumulation. Not expected to be widespread by any
means, but cannot rule it out. Return to VFR behind this front
then MVFR again towards the end of the TAF with the onset of yet
another warm front.                              -Muessle

&&

.MARINE...Low pressure moves inland today which will continue the
small craft seas and wind gusts over the next 24 hours. There will
be a brief lull in conditions this morning through around 10 AM,
but then winds will ramp up once again as they become southerly.
Speeds of 20-25 kt with gusts up to 30 kt are expected. However,
period of Gale Force Winds (gusts around 34 kt) are possible in
the far outer waters of PZZ272-273. Because they are not
widespread and will generally last for 6 hours or so, have not
issued a Gale Force Wind Warning at this time. If the low pressure
system intensifies or moves further south, winds will increase and
the hazard may be upgraded. Will continue to watch the low track
through the morning. Seas will build from 8-9 ft at 15 seconds, to
near 10 ft by Sunday afternoon. Behind the front associated with
the low, seas will build further to 14 ft at 15 seconds. Hazardous
seas are likely during this time. Winds will be less than 25 kt.
														-Muessle

&&

.BEACH HAZARDS...A long period westerly swell is entering our
coastal waters today at around 9 ft at 14 to 15 seconds and
building towards 12 ft at 15 seconds by Sunday. This will result
in an increased threat for sneaker waves across all our beaches.
Beachgoers should remain vigilant for waves occasionally running
up much farther onto the beach than background wave conditions.
Stay off of rocks, jetties and logs. Never turn your back on the
ocean. 														-42

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...Winter Weather Advisory from 4 PM this afternoon to 1 PM PST
     Sunday for ORZ121.

     Winter Storm Warning from 10 PM this evening to 10 AM PST Monday
     for ORZ126>128.

WA...Winter Storm Warning from 10 AM this morning to 10 AM PST Monday
     for WAZ211.

PZ...Small Craft Advisory until 7 PM PST Sunday for PZZ210-251>253-
     271>273.
&&

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