Issued: 7:12 AM PST Saturday, December 18, 2021
by Robert Hahn

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

Weather Synopsis

A well-defined low pressure slides down the coast of British Columbia on Saturday. The associated warm front lifted across the Cascades Friday night. The system continues to bring heavy snow to the Cascades early Saturday. However, warm air moving into the mid-levels through mid-day on Saturday makes the forecast tricky from Snoqualmie Pass southward. During the mid-day and early afternoon, hours expect a mix of freezing rain (west of the Cascade Crest), sleet (east of the Cascade Crest), and potentially rain in the central and southern Washington Cascades below 4500 ft. Areas that remain all snow could pick up 6-18" of snow by the end of the day with the most likely from Mt. Baker to Stevens Pass and also Paradise. Moderate to strong ridgeline winds should also peak in most areas with the cold frontal passage in the mid-afternoon hours. Areas east of the Cascade Crest may get the strongest WSW winds. Watch for heavy snowfall with a convergence zone developing in the Mountain Loop area in the late afternoon through early evening hours.

The sagging warm front focuses energy on the southern Cascades and Mt. Hood overnight. Mt. Hood could pick up 6-12" of snow with snow levels dropping to 4000 ft overnight. Washington state should cool significantly behind the Cold front as light snow showers continue across the region.

Heavy snowfall should linger over the Mt. Hood area and spills into the southern Washington Cascades as a perturbation begins to lift snowfall back northward on Sunday.

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
Saturday Heavy rain and snow tapering late in the afternoon. Moderate to strong ridgeline winds peaking in the morning hours.
Saturday Night Mostly cloudy with a chance of snow flurries.
Saturday Heavy snow decreasing slightly in the late afternoon. Moderate ridgeline winds with strong gusts.
Saturday Night Light snow showers.
Saturday Heavy rain and snow with rising temperatures through early afternoon. Convergence likely late afternoon in the Mountain Loop viscinity.
Saturday Night Heavy snowfall possible in convergence banding during the early evening, then light snow showers.
Saturday Heavy rain and snow at Paradise with moderate rain and snow for Crystal and White Pass. Strong sustained ridgeline winds are possible at Crystal from late morning onwards.
Saturday Night Moderate snow quickly tapering to light snow showers.
Saturday Heavy snow with a slight chance of a wintry mix in the early afternoon. Light to moderate E winds at the Pass switching W and increasing in the late afternoon.
Saturday Night Light snow showers with a chance of convergence in the early evening. Decreasing light to moderate winds switching E at the Pass by morning.
Saturday Heavy snow changing to a wintry mix (freezing rain west of the pass, sleet east of the Pass) during the late morning and early afternoon hours, then possibly rain below 4000 ft during the afternoon. Light to moderate E winds at the Pass switching W and increasing in the late afternoon.
Saturday Night Light snow showers. Decreasing light to moderate winds switching E at the Pass by morning.
Saturday Heavy snow.
Saturday Night Light snow showers.
Saturday Moderate to heavy snow with a wintry mix possible at lower elevations during the afternoon. Strong ridgeline winds.
Saturday Night Light snow showers.
Saturday Moderate snow with a wintry mix changing to rain at lower elevations during the afternoon. Moderate to strong ridgeline winds.
Saturday Night Light snow tapering to showers.
Saturday Moderate rain and snow. Moderate to strong ridgeline winds.
Saturday Night Moderate to heavy snow. Strong ridgeline winds decreasing into the moderate range.

Precipitation (in)

Saturday Saturday Night Sunday
4 am - 4 pm 4 pm - 4 am 4 am - 4 pm
Hurricane Ridge 1.00 LT 0.10 0
Mt Baker Ski Area 1.50 LT 0.25 0
Mt. Loop - Barlow Pass 2.00 0.25 0
Stevens Pass 1.00 - 1.50 LT 0.25 LT 0.10
Snoqualmie Pass 1.50 0.25 - 0.50 LT 0.10
Crystal Mt 0.50 LT 0.25 LT 0.25
Paradise 1.00 - 1.50 0.25 LT 0.25
White Pass 0.50 - 0.75 0.25 - 0.50 0.25 - 0.50
Washington Pass 1.00 - 1.50 LT 0.10 0
Mission Ridge 0.25 - 0.50 LT 0.10 LT 0.10
Salmon la Sac - Gallagher Head 0.75 -1.00 LT 0.25 LT 0.10
Tieton River - Darland Mt. 0.25 - 0.50 0.25 0.25 - 0.50
Mt Hood Meadows 0.25 - 0.50 0.75 -1.00 0.75 -1.00
Timberline 0.25 - 0.50 0.75 -1.00 1.00
Hurricane Ridge Precipitation (in)
Saturday 1.00
Saturday Night LT 0.10
Sunday 0
Mt Baker Ski Area Precipitation (in)
Saturday 1.50
Saturday Night LT 0.25
Sunday 0
Mt. Loop - Barlow Pass Precipitation (in)
Saturday 2.00
Saturday Night 0.25
Sunday 0
Stevens Pass Precipitation (in)
Saturday 1.00 - 1.50
Saturday Night LT 0.25
Sunday LT 0.10
Snoqualmie Pass Precipitation (in)
Saturday 1.50
Saturday Night 0.25 - 0.50
Sunday LT 0.10
Crystal Mt Precipitation (in)
Saturday 0.50
Saturday Night LT 0.25
Sunday LT 0.25
Paradise Precipitation (in)
Saturday 1.00 - 1.50
Saturday Night 0.25
Sunday LT 0.25
White Pass Precipitation (in)
Saturday 0.50 - 0.75
Saturday Night 0.25 - 0.50
Sunday 0.25 - 0.50
Washington Pass Precipitation (in)
Saturday 1.00 - 1.50
Saturday Night LT 0.10
Sunday 0
Mission Ridge Precipitation (in)
Saturday 0.25 - 0.50
Saturday Night LT 0.10
Sunday LT 0.10
Salmon la Sac - Gallagher Head Precipitation (in)
Saturday 0.75 -1.00
Saturday Night LT 0.25
Sunday LT 0.10
Tieton River - Darland Mt. Precipitation (in)
Saturday 0.25 - 0.50
Saturday Night 0.25
Sunday 0.25 - 0.50
Mt Hood Meadows Precipitation (in)
Saturday 0.25 - 0.50
Saturday Night 0.75 -1.00
Sunday 0.75 -1.00
Timberline Precipitation (in)
Saturday 0.25 - 0.50
Saturday Night 0.75 -1.00
Sunday 1.00

Snow Level (ft)

Saturday Morning Saturday Afternoon Saturday Evening Saturday Night Sunday Morning Sunday Afternoon
Olympics 4500' 4500' 1500' 1000' 1500' 2500'
West North 1500' 3000' 2000' 500' 1000' 2000'
West Central 1500' 3500' 2500' 1000' 1000' 2500'
West South 3000' 5000' 3000' 1500' 1000' 2000'
Stevens Pass 500' 2500' 3000' 1000' 1000' 2000'
Snoqualmie Pass 1000' 4000' 3000' 1000' 1000' 2000'
East North 0 0 1000' 500' 500' 2500'
East Central 500' 2000' 3000' 1000' 1000' 2000'
East South 2500' 5000' 4000' 2000' 2000' 2500'
Mt. Hood 4500' 6000' 5500' 3500' 3500' 3500'
Olympics Elevation
Saturday Morning 4500'
Saturday Afternoon 4500'
Saturday Evening 1500'
Saturday Night 1000'
Sunday Morning 1500'
Sunday Afternoon 2500'
West North Elevation
Saturday Morning 1500'
Saturday Afternoon 3000'
Saturday Evening 2000'
Saturday Night 500'
Sunday Morning 1000'
Sunday Afternoon 2000'
West Central Elevation
Saturday Morning 1500'
Saturday Afternoon 3500'
Saturday Evening 2500'
Saturday Night 1000'
Sunday Morning 1000'
Sunday Afternoon 2500'
West South Elevation
Saturday Morning 3000'
Saturday Afternoon 5000'
Saturday Evening 3000'
Saturday Night 1500'
Sunday Morning 1000'
Sunday Afternoon 2000'
Stevens Pass Elevation
Saturday Morning 500'
Saturday Afternoon 2500'
Saturday Evening 3000'
Saturday Night 1000'
Sunday Morning 1000'
Sunday Afternoon 2000'
Snoqualmie Pass Elevation
Saturday Morning 1000'
Saturday Afternoon 4000'
Saturday Evening 3000'
Saturday Night 1000'
Sunday Morning 1000'
Sunday Afternoon 2000'
East North Elevation
Saturday Morning 0'
Saturday Afternoon 0'
Saturday Evening 1000'
Saturday Night 500'
Sunday Morning 500'
Sunday Afternoon 2500'
East Central Elevation
Saturday Morning 500'
Saturday Afternoon 2000'
Saturday Evening 3000'
Saturday Night 1000'
Sunday Morning 1000'
Sunday Afternoon 2000'
East South Elevation
Saturday Morning 2500'
Saturday Afternoon 5000'
Saturday Evening 4000'
Saturday Night 2000'
Sunday Morning 2000'
Sunday Afternoon 2500'
Mt. Hood Elevation
Saturday Morning 4500'
Saturday Afternoon 6000'
Saturday Evening 5500'
Saturday Night 3500'
Sunday Morning 3500'
Sunday Afternoon 3500'

5000' Temperatures (°F)

Saturday Saturday Night
Max / Min Max / Min
Olympics 32 / 21 21 / 16
West North 30 / 24 21 / 17
West Central 33 / 25 24 / 14
West South 33 / 27 26 / 17
Stevens Pass 32 / 24 25 / 17
Snoqualmie Pass 32 / 24 25 / 17
East North 25 / 15 23 / 14
East Central 31 / 21 25 / 18
East South 34 / 28 27 / 20
Mt. Hood 35 / 31 34 / 29
Olympics 5000' Temperature Forecast
(Max / Min)
Saturday 32 / 21
Saturday Night 21 / 16
West North 5000' Temperature Forecast
(Max / Min)
Saturday 30 / 24
Saturday Night 21 / 17
West Central 5000' Temperature Forecast
(Max / Min)
Saturday 33 / 25
Saturday Night 24 / 14
West South 5000' Temperature Forecast
(Max / Min)
Saturday 33 / 27
Saturday Night 26 / 17
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Saturday 32 / 24
Saturday Night 25 / 17
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Saturday 32 / 24
Saturday Night 25 / 17
East North 5000' Temperature Forecast
(Max / Min)
Saturday 25 / 15
Saturday Night 23 / 14
East Central 5000' Temperature Forecast
(Max / Min)
Saturday 31 / 21
Saturday Night 25 / 18
East South 5000' Temperature Forecast
(Max / Min)
Saturday 34 / 28
Saturday Night 27 / 20
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Saturday 35 / 31
Saturday Night 34 / 29

Ridgeline Winds (mph)

Saturday Morning Saturday Afternoon Saturday Evening Saturday Night
Olympics SW 25-35 WSW 15-25 WSW 5-15 WSW 0-10
West North SSW 20-30 WSW 20-30 WSW 15-25 W 0-10
West Central SW 25-35 WSW 20-30 WNW 10-20 NW 5-15
West South SW 20-30 WSW 20-30 WSW 10-20 NW 0-10
Stevens Pass SW 15-25 WSW 20-30 W 15-25 WNW 5-15
Snoqualmie Pass SW 15-25 WSW 20-30 W 15-25 NW 10-20
East North SW 15-25 WSW 15-25 W 20-30 WNW 10-20
East Central WSW 25-35 WSW 30-40 W 20-30 WNW 10-20
East South WSW 20-30 WSW 25-35 W 15-25 W 5-15
Mt. Hood WSW 20-30 SW 30-40 WSW 30-40 WSW 20-30
Olympics Ridgeline Winds (mph)
Saturday Morning SW 25-35
Saturday Afternoon WSW 15-25
Saturday Evening WSW 5-15
Saturday Night WSW 0-10
West North Ridgeline Winds (mph)
Saturday Morning SSW 20-30
Saturday Afternoon WSW 20-30
Saturday Evening WSW 15-25
Saturday Night W 0-10
West Central Ridgeline Winds (mph)
Saturday Morning SW 25-35
Saturday Afternoon WSW 20-30
Saturday Evening WNW 10-20
Saturday Night NW 5-15
West South Ridgeline Winds (mph)
Saturday Morning SW 20-30
Saturday Afternoon WSW 20-30
Saturday Evening WSW 10-20
Saturday Night NW 0-10
Stevens Pass Ridgeline Winds (mph)
Saturday Morning SW 15-25
Saturday Afternoon WSW 20-30
Saturday Evening W 15-25
Saturday Night WNW 5-15
Snoqualmie Pass Ridgeline Winds (mph)
Saturday Morning SW 15-25
Saturday Afternoon WSW 20-30
Saturday Evening W 15-25
Saturday Night NW 10-20
East North Ridgeline Winds (mph)
Saturday Morning SW 15-25
Saturday Afternoon WSW 15-25
Saturday Evening W 20-30
Saturday Night WNW 10-20
East Central Ridgeline Winds (mph)
Saturday Morning WSW 25-35
Saturday Afternoon WSW 30-40
Saturday Evening W 20-30
Saturday Night WNW 10-20
East South Ridgeline Winds (mph)
Saturday Morning WSW 20-30
Saturday Afternoon WSW 25-35
Saturday Evening W 15-25
Saturday Night W 5-15
Mt. Hood Ridgeline Winds (mph)
Saturday Morning WSW 20-30
Saturday Afternoon SW 30-40
Saturday Evening WSW 30-40
Saturday Night WSW 20-30

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

Previous forecast from Dec 17, 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’.