Issued: 7:08 AM PST Sunday, December 13, 2020
by Robert Hahn

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

Weather Synopsis

An occluded front passed over the region early this morning, bringing up to 4" of snow with a band of light snow. The frontal passage allows a large trough with organized bands of precipitation to move into the region. Southerly winds have turned slightly more southwesterly and E flow through the mountain gaps should continue to ease on Sunday. The east side cold pool should also weaken as slightly milder Pacific air moves into the region. Expect bands of organized heavier snow showers with lighter mountain-induced snow in between for the Cascades west slopes and passes with lighter snow showers spilling over onto the east slopes.

The SW flow should favor the volcanoes on Sunday. We expect 6-12" for Mt Baker and Paradise, with 8-12" for Mt. Hood and around 4-6" for the Cascade Passes.

As the trough centers on the region Sunday night, winds shift westerly. Expect another 2-8" of snow for the west slopes and Cascade Passes by Sunday morning.

On Monday, the trough shifts east and light snow shower activity decreases, but several more inches of snow are possible.

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 Bands of light rain and snow with moderate intensity at times. Gradual cooling. Decreasing light to moderate ridgeline winds.
Sunday Night Light snow showers. Light ridgeline winds.
Sunday Bands of moderate snow showers, heavy at times. Decreasing light to moderate ridgeline winds.
Sunday Night Light snow showers. Light ridgeline winds.
Sunday Bands of light snow showers with moderate intensity at times. Decreasing light to moderate ridgeline winds.
Sunday Night Light snow showers. Light to moderate ridgeline winds.
Sunday Moderate snow showers, heavy at times (Paradise) and light snow showers (Crystal, White Pass). Decreasing light to moderate winds.
Sunday Night Moderate snow showers (Paradise), light elsewhere. Light ridgeline winds.
Sunday Light snow showers. Light ridgeline and E pass-level winds.
Sunday Night Light to moderate snow showers. Light ridgeline and E shifting W pass-level winds.
Sunday Light snow showers. Decreasing light to moderate ridgeline and E winds through the passes becoming light in the afternoon.
Sunday Night Light to moderate snow showers. Decreasing light to moderate ridgeline and light E shifting W pass-level winds.
Sunday Light snow showers. Light ridgeline winds.
Sunday Night Light snow showers. Light to moderate winds.
Sunday Light snow showers. Light to moderate ridgeline winds.
Sunday Night Light snow showers, heaviest near the Cascade crest. Moderate ridgeline winds.
Sunday Light snow showers. Light ridgeline winds.
Sunday Night Light snow showers. Light to moderate ridgeline winds.
Sunday Periods of heavy snow. Moderate ridgeline winds.
Sunday Night Moderate snow showers. Moderate ridgeline winds.

Precipitation (in)

Sunday Sunday Night Monday
4 am - 4 pm 4 pm - 4 am 4 am - 4 pm
Hurricane Ridge 0.25 LT 0.25 LT 0.10
Mt Baker Ski Area 0.75 0.25 LT 0.25
Mt. Loop - Barlow Pass 0.25 - 0.50 0.25 - 0.50 LT 0.25
Stevens Pass 0.25 0.25 - 0.50 0.25
Snoqualmie Pass 0.25 - 0.50 0.25 - 0.50 0.25
Crystal Mt 0.25 LT 0.25 LT 0.10
Paradise 0.75 0.50 - 0.75 LT 0.25
White Pass 0.25 LT 0.25 LT 0.10
Washington Pass LT 0.25 LT 0.10 LT 0.10
Mission Ridge LT 0.10 0 0
Salmon la Sac - Gallagher Head 0.25 LT 0.25 LT 0.25
Tieton River - Darland Mt. LT 0.25 LT 0.10 LT 0.10
Mt Hood Meadows 0.75 -1.00 0.50 LT 0.25
Timberline 1.00 0.50 - 0.75 LT 0.25
Hurricane Ridge Precipitation (in)
Sunday 0.25
Sunday Night LT 0.25
Monday LT 0.10
Mt Baker Ski Area Precipitation (in)
Sunday 0.75
Sunday Night 0.25
Monday LT 0.25
Mt. Loop - Barlow Pass Precipitation (in)
Sunday 0.25 - 0.50
Sunday Night 0.25 - 0.50
Monday LT 0.25
Stevens Pass Precipitation (in)
Sunday 0.25
Sunday Night 0.25 - 0.50
Monday 0.25
Snoqualmie Pass Precipitation (in)
Sunday 0.25 - 0.50
Sunday Night 0.25 - 0.50
Monday 0.25
Crystal Mt Precipitation (in)
Sunday 0.25
Sunday Night LT 0.25
Monday LT 0.10
Paradise Precipitation (in)
Sunday 0.75
Sunday Night 0.50 - 0.75
Monday LT 0.25
White Pass Precipitation (in)
Sunday 0.25
Sunday Night LT 0.25
Monday LT 0.10
Washington Pass Precipitation (in)
Sunday LT 0.25
Sunday Night LT 0.10
Monday LT 0.10
Mission Ridge Precipitation (in)
Sunday LT 0.10
Sunday Night 0
Monday 0
Salmon la Sac - Gallagher Head Precipitation (in)
Sunday 0.25
Sunday Night LT 0.25
Monday LT 0.25
Tieton River - Darland Mt. Precipitation (in)
Sunday LT 0.25
Sunday Night LT 0.10
Monday LT 0.10
Mt Hood Meadows Precipitation (in)
Sunday 0.75 -1.00
Sunday Night 0.50
Monday LT 0.25
Timberline Precipitation (in)
Sunday 1.00
Sunday Night 0.50 - 0.75
Monday LT 0.25

Snow Level (ft)

Sunday Morning* Sunday Afternoon* Sunday Evening* Sunday Night Monday Morning Monday Afternoon
Olympics 4000' 4000' 3500' 3000' 3000' 3000'
West North 1500' 2000' 2500' 2500' 2500' 3000'
West Central 1500' 1500' 2500' 3000' 3000' 3000'
West South 2000' 2500' 2500' 3000' 2500' 3000'
Stevens Pass 1000' 1500' 2000' 2500' 3000' 3000'
Snoqualmie Pass 1500' 2000' 2500' 2500' 3000' 3000'
East North 0 1000' 1500' 2000' 2000' 2500'
East Central 500' 1500' 1500' 2000' 2500' 3000'
East South 1000' 2000' 2500' 2500' 2500' 3000'
Mt. Hood 2500' 3000' 3500' 3000' 3000' 3000'
Olympics Elevation
Sunday Morning* 4000'
Sunday Afternoon* 4000'
Sunday Evening* 3500'
Sunday Night 3000'
Monday Morning 3000'
Monday Afternoon 3000'
West North Elevation
Sunday Morning* 1500'
Sunday Afternoon* 2000'
Sunday Evening* 2500'
Sunday Night 2500'
Monday Morning 2500'
Monday Afternoon 3000'
West Central Elevation
Sunday Morning* 1500'
Sunday Afternoon* 1500'
Sunday Evening* 2500'
Sunday Night 3000'
Monday Morning 3000'
Monday Afternoon 3000'
West South Elevation
Sunday Morning* 2000'
Sunday Afternoon* 2500'
Sunday Evening* 2500'
Sunday Night 3000'
Monday Morning 2500'
Monday Afternoon 3000'
Stevens Pass Elevation
Sunday Morning* 1000'
Sunday Afternoon* 1500'
Sunday Evening* 2000'
Sunday Night 2500'
Monday Morning 3000'
Monday Afternoon 3000'
Snoqualmie Pass Elevation
Sunday Morning* 1500'
Sunday Afternoon* 2000'
Sunday Evening* 2500'
Sunday Night 2500'
Monday Morning 3000'
Monday Afternoon 3000'
East North Elevation
Sunday Morning* 0'
Sunday Afternoon* 1000'
Sunday Evening* 1500'
Sunday Night 2000'
Monday Morning 2000'
Monday Afternoon 2500'
East Central Elevation
Sunday Morning* 500'
Sunday Afternoon* 1500'
Sunday Evening* 1500'
Sunday Night 2000'
Monday Morning 2500'
Monday Afternoon 3000'
East South Elevation
Sunday Morning* 1000'
Sunday Afternoon* 2000'
Sunday Evening* 2500'
Sunday Night 2500'
Monday Morning 2500'
Monday Afternoon 3000'
Mt. Hood Elevation
Sunday Morning* 2500'
Sunday Afternoon* 3000'
Sunday Evening* 3500'
Sunday Night 3000'
Monday Morning 3000'
Monday Afternoon 3000'

5000' Temperatures (°F)

Sunday Sunday Night
Max / Min Max / Min
Olympics 31 / 28 28 / 25
West North 29 / 23 28 / 26
West Central 26 / 21 28 / 26
West South 30 / 25 28 / 26
Stevens Pass 25 / 18 27 / 25
Snoqualmie Pass 26 / 19 27 / 26
East North 21 / 15 25 / 19
East Central 25 / 18 27 / 24
East South 30 / 19 26 / 24
Mt. Hood 31 / 28 29 / 27
Olympics 5000' Temperature Forecast
(Max / Min)
Sunday 31 / 28
Sunday Night 28 / 25
West North 5000' Temperature Forecast
(Max / Min)
Sunday 29 / 23
Sunday Night 28 / 26
West Central 5000' Temperature Forecast
(Max / Min)
Sunday 26 / 21
Sunday Night 28 / 26
West South 5000' Temperature Forecast
(Max / Min)
Sunday 30 / 25
Sunday Night 28 / 26
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Sunday 25 / 18
Sunday Night 27 / 25
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Sunday 26 / 19
Sunday Night 27 / 26
East North 5000' Temperature Forecast
(Max / Min)
Sunday 21 / 15
Sunday Night 25 / 19
East Central 5000' Temperature Forecast
(Max / Min)
Sunday 25 / 18
Sunday Night 27 / 24
East South 5000' Temperature Forecast
(Max / Min)
Sunday 30 / 19
Sunday Night 26 / 24
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Sunday 31 / 28
Sunday Night 29 / 27

Ridgeline Winds (mph)

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

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

Previous forecast from Dec 12, 2020

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’.