Issued: 7:05 AM PST Sunday, December 12, 2021
by Dennis D'Amico

Jump to: Weather Forecast I Precipitation I Snow Level I 5000' Temps I Ridgeline Winds I

Weather Synopsis

Showers will rotate across the area in SW flow today, emanating from a cold upper level trough positioned over the NE Pacific.  Most showers will be light, but occasionally clusters will produce moderate snowfall rates, with 2-5" of additional snowfall across the west slopes of the Cascades, Olympics and Mt Hood and lighter amounts to the east side of the Cascades. Temperatures have cooled significantly since Saturday morning into the teens and 20s in the mountains and temps will more or less hold steady today. Additional light snow showers are expected Sunday night. 

A weak frontal system will approach the coast overnight, briefly increasing offshore gradients and SE-ridgeline winds. This should bring a period of light snow to the mountains mainly late Sunday night through late Monday morning.  An upslope component will help keep the snow steadier with slightly higher accumulations along the east slopes of the Cascades, including places like the Methow Valley, the Wentachee Mts and the Teanaways.  After the front washes out in the afternoon and the flow aloft becomes more southerly, the chances for sunshine will increase for the second half of the day. 

Weather Forecast

Olympics
West North
West Central
West South
Stevens Pass
Snoqualmie Pass
East North
East Central
East South
Mt. Hood
Use dropdown to select your zone
Sunday Cloudy with light to occasionally moderate snow showers.
Sunday Night Cloudy with scattered light to occasionally moderate snow showers in the evening becoming light snow after midnight.
Sunday Cloudy with light to occasionally moderate snow showers. Winds becoming strong in the afternoon.
Sunday Night Cloudy with scattered light to occasionally moderate snow showers.
Sunday Cloudy with light to occasionally moderate snow showers.
Sunday Night Cloudy with scattered light snow showers.
Sunday Cloudy with light to occasionally moderate snow showers. Showers heaviest Paradise area.
Sunday Night Cloudy with scattered light snow showers.
Sunday Cloudy with light snow showers. Light pass level winds switching from west to east mid-day
Sunday Night Cloudy with scattered light snow showers. Light east winds at Pass level becoming moderate after midnight.
Sunday Cloudy with light snow showers. Light pass level winds switching from west to east mid-day
Sunday Night Cloudy with scattered light snow showers. Light east winds at Pass level becoming moderate after midnight.
Sunday Cloudy with light snow showers, heaviest near the crest.
Sunday Night Cloudy with scattered light snow showers increasing late.
Sunday Cloudy with light snow showers, heaviest near the crest.
Sunday Night Cloudy with scattered light snow showers increasing late.
Sunday Cloudy with light snow showers, heaviest near the crest.
Sunday Night Cloudy with scattered light snow showers increasing late.
Sunday Cloudy with light to moderate snow showers. Strong winds.
Sunday Night Cloudy with scattered light snow showers.

Issued: 7:05 AM PST Sunday, December 12, 2021

Precipitation (in)

Sunday Sunday Night Monday
4 am - 4 pm 4 pm - 4 am 4 am - 4 pm
Hurricane Ridge 0.25 - 0.50 LT 0.25 0.25
Mt Baker Ski Area 0.25 - 0.50 0.25 0.25
Mt. Loop - Barlow Pass 0.25 - 0.50 LT 0.25 LT 0.25
Stevens Pass LT 0.25 LT 0.10 LT 0.10
Snoqualmie Pass 0.25 LT 0.25 LT 0.25
Crystal Mt 0.25 LT 0.25 LT 0.25
Paradise 0.25 - 0.50 0.25 LT 0.25
White Pass LT 0.25 LT 0.25 LT 0.10
Washington Pass LT 0.25 LT 0.25 LT 0.25
Mission Ridge LT 0.10 LT 0.25 0.25
Salmon la Sac - Gallagher Head LT 0.25 LT 0.25 0.25
Tieton River - Darland Mt. LT 0.25 LT 0.25 0.25
Mt Hood Meadows 0.25 - 0.50 0.25 LT 0.25
Timberline 0.25 - 0.50 0.25 LT 0.10
Hurricane Ridge Precipitation (in)
Sunday 0.25 - 0.50
Sunday Night LT 0.25
Monday 0.25
Mt Baker Ski Area Precipitation (in)
Sunday 0.25 - 0.50
Sunday Night 0.25
Monday 0.25
Mt. Loop - Barlow Pass Precipitation (in)
Sunday 0.25 - 0.50
Sunday Night LT 0.25
Monday LT 0.25
Stevens Pass Precipitation (in)
Sunday LT 0.25
Sunday Night LT 0.10
Monday LT 0.10
Snoqualmie Pass Precipitation (in)
Sunday 0.25
Sunday Night LT 0.25
Monday LT 0.25
Crystal Mt Precipitation (in)
Sunday 0.25
Sunday Night LT 0.25
Monday LT 0.25
Paradise Precipitation (in)
Sunday 0.25 - 0.50
Sunday Night 0.25
Monday LT 0.25
White Pass Precipitation (in)
Sunday LT 0.25
Sunday Night LT 0.25
Monday LT 0.10
Washington Pass Precipitation (in)
Sunday LT 0.25
Sunday Night LT 0.25
Monday LT 0.25
Mission Ridge Precipitation (in)
Sunday LT 0.10
Sunday Night LT 0.25
Monday 0.25
Salmon la Sac - Gallagher Head Precipitation (in)
Sunday LT 0.25
Sunday Night LT 0.25
Monday 0.25
Tieton River - Darland Mt. Precipitation (in)
Sunday LT 0.25
Sunday Night LT 0.25
Monday 0.25
Mt Hood Meadows Precipitation (in)
Sunday 0.25 - 0.50
Sunday Night 0.25
Monday LT 0.25
Timberline Precipitation (in)
Sunday 0.25 - 0.50
Sunday Night 0.25
Monday LT 0.10

Issued: 7:05 AM PST Sunday, December 12, 2021

Snow Level (ft)

Sunday Morning Sunday Afternoon Sunday Evening Sunday Night Monday Morning Monday Afternoon
Olympics 1500' 2000' 1500' 1500' 1000' 2000'
West North 1000' 1500' 1000' 1000' 500' 1500'
West Central 1500' 1500' 1000' 1000' 500' 1500'
West South 1500' 2000' 1500' 1500' 1000' 2500'
Stevens Pass 1500' 1500' 1000' 0 500' 1500'
Snoqualmie Pass 1500' 1500' 1000' 1000' 500' 2000'
East North 1500' 1500' 1000' 0 0 1500'
East Central 1500' 1500' 1000' 0 0 1500'
East South 1500' 2000' 1500' 1000' 1000' 2000'
Mt. Hood 2500' 2000' 2000' 1500' 1500' 2500'
Olympics Elevation
Sunday Morning 1500'
Sunday Afternoon 2000'
Sunday Evening 1500'
Sunday Night 1500'
Monday Morning 1000'
Monday Afternoon 2000'
West North Elevation
Sunday Morning 1000'
Sunday Afternoon 1500'
Sunday Evening 1000'
Sunday Night 1000'
Monday Morning 500'
Monday Afternoon 1500'
West Central Elevation
Sunday Morning 1500'
Sunday Afternoon 1500'
Sunday Evening 1000'
Sunday Night 1000'
Monday Morning 500'
Monday Afternoon 1500'
West South Elevation
Sunday Morning 1500'
Sunday Afternoon 2000'
Sunday Evening 1500'
Sunday Night 1500'
Monday Morning 1000'
Monday Afternoon 2500'
Stevens Pass Elevation
Sunday Morning 1500'
Sunday Afternoon 1500'
Sunday Evening 1000'
Sunday Night 0'
Monday Morning 500'
Monday Afternoon 1500'
Snoqualmie Pass Elevation
Sunday Morning 1500'
Sunday Afternoon 1500'
Sunday Evening 1000'
Sunday Night 1000'
Monday Morning 500'
Monday Afternoon 2000'
East North Elevation
Sunday Morning 1500'
Sunday Afternoon 1500'
Sunday Evening 1000'
Sunday Night 0'
Monday Morning 0'
Monday Afternoon 1500'
East Central Elevation
Sunday Morning 1500'
Sunday Afternoon 1500'
Sunday Evening 1000'
Sunday Night 0'
Monday Morning 0'
Monday Afternoon 1500'
East South Elevation
Sunday Morning 1500'
Sunday Afternoon 2000'
Sunday Evening 1500'
Sunday Night 1000'
Monday Morning 1000'
Monday Afternoon 2000'
Mt. Hood Elevation
Sunday Morning 2500'
Sunday Afternoon 2000'
Sunday Evening 2000'
Sunday Night 1500'
Monday Morning 1500'
Monday Afternoon 2500'

Issued: 7:05 AM PST Sunday, December 12, 2021

5000' Temperatures (°F)

Sunday Sunday Night
Max / Min Max / Min
Olympics 21 / 16 22 / 17
West North 21 / 16 21 / 17
West Central 20 / 18 21 / 17
West South 22 / 19 22 / 18
Stevens Pass 22 / 16 22 / 17
Snoqualmie Pass 21 / 17 22 / 16
East North 21 / 16 20 / 15
East Central 21 / 16 22 / 18
East South 24 / 15 22 / 18
Mt. Hood 25 / 20 25 / 21
Olympics 5000' Temperature Forecast
(Max / Min)
Sunday 21 / 16
Sunday Night 22 / 17
West North 5000' Temperature Forecast
(Max / Min)
Sunday 21 / 16
Sunday Night 21 / 17
West Central 5000' Temperature Forecast
(Max / Min)
Sunday 20 / 18
Sunday Night 21 / 17
West South 5000' Temperature Forecast
(Max / Min)
Sunday 22 / 19
Sunday Night 22 / 18
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Sunday 22 / 16
Sunday Night 22 / 17
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Sunday 21 / 17
Sunday Night 22 / 16
East North 5000' Temperature Forecast
(Max / Min)
Sunday 21 / 16
Sunday Night 20 / 15
East Central 5000' Temperature Forecast
(Max / Min)
Sunday 21 / 16
Sunday Night 22 / 18
East South 5000' Temperature Forecast
(Max / Min)
Sunday 24 / 15
Sunday Night 22 / 18
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Sunday 25 / 20
Sunday Night 25 / 21

Issued: 7:05 AM PST Sunday, December 12, 2021

Ridgeline Winds (mph)

Sunday Morning Sunday Afternoon Sunday Evening Sunday Night
Olympics SW 10-20 SSW 15-25 S 5-15 SE 20-30
West North SW 5-15 SSW 20-30 SSW 10-20 SE 10-20
West Central SW 20-30 SW 15-25 SSW 10-20 SE 10-20
West South WSW 15-25 SW 15-25 SSE 5-15 SE 20-30
Stevens Pass WSW 10-20 SW 5-15 SE 0-10 SE 15-25
Snoqualmie Pass WSW 20-30 SW 10-20 S 0-10 SE 20-30
East North SW 15-25 SW 5-15 S 10-20 SE 15-25
East Central WSW 25-35 SW 10-20 SSE 5-15 SE 10-20
East South WSW 15-25 SSW 10-20 SSE 5-15 SE 10-20
Mt. Hood WSW 25-35 SW 20-30 SSE 10-20 S 15-25
Olympics Ridgeline Winds (mph)
Sunday Morning SW 10-20
Sunday Afternoon SSW 15-25
Sunday Evening S 5-15
Sunday Night SE 20-30
West North Ridgeline Winds (mph)
Sunday Morning SW 5-15
Sunday Afternoon SSW 20-30
Sunday Evening SSW 10-20
Sunday Night SE 10-20
West Central Ridgeline Winds (mph)
Sunday Morning SW 20-30
Sunday Afternoon SW 15-25
Sunday Evening SSW 10-20
Sunday Night SE 10-20
West South Ridgeline Winds (mph)
Sunday Morning WSW 15-25
Sunday Afternoon SW 15-25
Sunday Evening SSE 5-15
Sunday Night SE 20-30
Stevens Pass Ridgeline Winds (mph)
Sunday Morning WSW 10-20
Sunday Afternoon SW 5-15
Sunday Evening SE 0-10
Sunday Night SE 15-25
Snoqualmie Pass Ridgeline Winds (mph)
Sunday Morning WSW 20-30
Sunday Afternoon SW 10-20
Sunday Evening S 0-10
Sunday Night SE 20-30
East North Ridgeline Winds (mph)
Sunday Morning SW 15-25
Sunday Afternoon SW 5-15
Sunday Evening S 10-20
Sunday Night SE 15-25
East Central Ridgeline Winds (mph)
Sunday Morning WSW 25-35
Sunday Afternoon SW 10-20
Sunday Evening SSE 5-15
Sunday Night SE 10-20
East South Ridgeline Winds (mph)
Sunday Morning WSW 15-25
Sunday Afternoon SSW 10-20
Sunday Evening SSE 5-15
Sunday Night SE 10-20
Mt. Hood Ridgeline Winds (mph)
Sunday Morning WSW 25-35
Sunday Afternoon SW 20-30
Sunday Evening SSE 10-20
Sunday Night S 15-25

Jump to: Weather Forecast I Precipitation I Snow Level I 5000' Temps I Ridgeline Winds I

Previous forecast from Dec 11, 2021

The NWAC program is administered by the USDA-Forest Service and operates from the National Weather Service Forecast Office in Seattle. NWAC services are made possible by important collaboration and support from a wide variety of federal, state and private cooperators.

The 5000’ temperature forecast does not imply a trend over the 12 hr period and only represents the max and min temperatures within a 12 hr period in the zone. The 6-hr snow level forecast, the forecast discussion, and weather forecast sections may add detail regarding temperature trends.

The snow level forecast represents the general snow level over a 6 hr time period. Freezing levels are forecast when precipitation is not expected.

*Easterly or offshore flow is highlighted with an asterisk when we expect relatively cool east winds in the major Cascade Passes. Easterly flow will often lead to temperature inversions and is a key variable for forecasting precipitation type in the Cascade Passes. Strong easterly flow events can affect terrain on a more regional scale.

Ridgeline winds are the average wind speed and direction over a 6 hr time period.

The wind forecast represents an elevation range instead of a single elevation slice. The elevation range overlaps with the near and above treeline elevation bands in the avalanche forecast and differs per zone.

Wind direction indicates the direction the wind originates or comes from on the 16-point compass rose.

Water Equivalent (WE) is the liquid water equivalent of all precipitation types; rain, snow, ice pellets, etc., forecast to the hundredth of an inch at specific locations. To use WE as a proxy for snowfall amounts, start with a snow to water ratio of 10:1 (10 inches of snow = 1 inch WE). Temperatures at or near freezing will generally have a lower ratio (heavy wet snow) and very cold temperatures can have a much higher ratio (dry fluffy snow).

The label LT, is shorthand for ‘less than’.