Issued: 2:03 PM PST Thursday, December 23, 2021
by Dennis D'Amico

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

Weather Synopsis

Westerly flow continues to produce snow showers up and down the Cascades with strong ridgeline winds affecting most areas this afternoon. More moderate showers will affect the Mt Hood area and central Cascades including, the Mt Loop, Stevens and Snoqualmie Passes through this evening. Snow showers will become somewhat lighter overnight with any sort of convergence signature in the central Cascades lifting back to the north as a new system approaches. 

A low pressure system will dive southward along the B.C. coast with a frontal band reaching the Olympics around midnight. The frontal band will rotate over to the Cascades reinvigorating light snowfall over all areas early Friday morning but weaken as the low continues to pull south offshore. Snow showers will likely become more scattered in the afternoon for central and north Cascades.  A trailing upper level feature should keep the snow showers piling up over the West South zone and for Mt Hood where the most snow is expected through 4 pm Friday.  There will be a sharp delination in strong winds on Friday as well, with much stronger winds forecast for the extreme southern Washington Cascades and Mt Hood. 

Another low will follow a similar pattern Friday evening through Saturday, diving off the Washington coast and rotating precipitation inland. There's more uncertainty the further out in time in this pattern for precipitation amounts, but it's likely all areas will see periods of light snow through the first half of the weekend with a few areas of more significant snowfall totals. Snow levels will fall towards sea level over the weekend, setting up a major cold snap next week. 

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
Thursday Night Light snow showers becoming light to moderate snow overnight.
Friday Light to occasionally moderate snow becoming scattered light snow showers mid-morning.
Thursday Night Mostly cloudy with scattered light snow showers overnight, then light snow developing late.
Friday Light to occasionally moderate snow becoming light snow showers mid-morning.
Thursday Night Light to moderate snow showers. Moderate to strong ridgeline winds.
Friday Light to occasionally moderate snow becoming light snow showers mid-morning.
Thursday Night Scattered light snow showers becoming light to occasionally moderate snow after midnight. Strong ridgeline winds.
Friday Light to occasionally moderate snow becoming light snow showers mid-morning. Strong wind St Helens area and south.
Thursday Night Light to moderate snow showers in the evening becoming scattered after midnight. Strong to moderate ridgeline and Pass level westerly winds decreasing overnight.
Friday Light to occasionally moderate snow becoming scattered light snow showers mid-morning. Light east wind at Pass level becoming variable in the afternoon.
Thursday Night Light to moderate snow showers in the evening becoming scattered after midnight. Strong ridgeline and Pass level westerly winds decreasing overnight.
Friday Light to occasionally moderate snow becoming scattered light snow showers mid-morning. Light east wind at Pass level becoming variable in the afternoon.
Thursday Night Scattered light snow showers decreasing after midnight.
Friday Light snow becoming scattered light snow showers mid-morning.
Thursday Night Light snow showers, occasionally heavy near the Cascade crest becoming scattered light snow showers after midnight. Strong ridgeline winds decreasing overnight.
Friday Light snow becoming scattered light snow showers mid-morning.
Thursday Night Light snow showers, occasionally heavy near the Cascade crest becoming scattered light snow showers after midnight. Strong ridgeline winds decreasing overnight.
Friday Light snow becoming light snow showers mid-morning. Strong ridgeline winds.
Thursday Night Light to moderate snow showers becoming light to occasionally moderate snow late. Strong ridgeline winds.
Friday Moderate snow. Strong ridgeline winds.

Issued: 2:03 PM PST Thursday, December 23, 2021

Precipitation (in)

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

Issued: 2:03 PM PST Thursday, December 23, 2021

Snow Level (ft)

Thursday Evening Thursday Night Friday Morning Friday Afternoon Friday Evening Friday Night Saturday Morning Saturday Afternoon
Olympics 1000' 1000' 1000' 1500' 500' 0 0 500'
West North 1000' 0 500' 1000' 0 0 0 0
West Central 1000' 500' 1000' 1500' 500' 0 0 500'
West South 1500' 1000' 1000' 1500' 500' 0 0 500'
Stevens Pass 1000' 500' 1000' 1000' 500' 0 0 500'
Snoqualmie Pass 1000' 500' 1000' 1500' 500' 0 0 500'
East North 1000' 0 500' 1000' 0 0 0 0
East Central 1000' 500' 500' 1000' 0 0 0 0
East South 1000' 500' 1000' 1500' 500' 0 0 500'
Mt. Hood 2000' 1500' 1500' 2000' 1500' 1000' 1000' 1500'
Olympics Elevation
Thursday Evening 1000'
Thursday Night 1000'
Friday Morning 1000'
Friday Afternoon 1500'
Friday Evening 500'
Friday Night 0'
Saturday Morning 0'
Saturday Afternoon 500'
West North Elevation
Thursday Evening 1000'
Thursday Night 0'
Friday Morning 500'
Friday Afternoon 1000'
Friday Evening 0'
Friday Night 0'
Saturday Morning 0'
Saturday Afternoon 0'
West Central Elevation
Thursday Evening 1000'
Thursday Night 500'
Friday Morning 1000'
Friday Afternoon 1500'
Friday Evening 500'
Friday Night 0'
Saturday Morning 0'
Saturday Afternoon 500'
West South Elevation
Thursday Evening 1500'
Thursday Night 1000'
Friday Morning 1000'
Friday Afternoon 1500'
Friday Evening 500'
Friday Night 0'
Saturday Morning 0'
Saturday Afternoon 500'
Stevens Pass Elevation
Thursday Evening 1000'
Thursday Night 500'
Friday Morning 1000'
Friday Afternoon 1000'
Friday Evening 500'
Friday Night 0'
Saturday Morning 0'
Saturday Afternoon 500'
Snoqualmie Pass Elevation
Thursday Evening 1000'
Thursday Night 500'
Friday Morning 1000'
Friday Afternoon 1500'
Friday Evening 500'
Friday Night 0'
Saturday Morning 0'
Saturday Afternoon 500'
East North Elevation
Thursday Evening 1000'
Thursday Night 0'
Friday Morning 500'
Friday Afternoon 1000'
Friday Evening 0'
Friday Night 0'
Saturday Morning 0'
Saturday Afternoon 0'
East Central Elevation
Thursday Evening 1000'
Thursday Night 500'
Friday Morning 500'
Friday Afternoon 1000'
Friday Evening 0'
Friday Night 0'
Saturday Morning 0'
Saturday Afternoon 0'
East South Elevation
Thursday Evening 1000'
Thursday Night 500'
Friday Morning 1000'
Friday Afternoon 1500'
Friday Evening 500'
Friday Night 0'
Saturday Morning 0'
Saturday Afternoon 500'
Mt. Hood Elevation
Thursday Evening 2000'
Thursday Night 1500'
Friday Morning 1500'
Friday Afternoon 2000'
Friday Evening 1500'
Friday Night 1000'
Saturday Morning 1000'
Saturday Afternoon 1500'

Issued: 2:03 PM PST Thursday, December 23, 2021

5000' Temperatures (°F)

Thursday Night Friday
Max / Min Max / Min
Olympics 20 / 17 25 / 17
West North 19 / 16 24 / 18
West Central 20 / 17 25 / 18
West South 21 / 19 27 / 19
Stevens Pass 21 / 17 25 / 16
Snoqualmie Pass 20 / 17 25 / 17
East North 16 / 11 21 / 12
East Central 21 / 16 23 / 16
East South 20 / 17 25 / 18
Mt. Hood 23 / 20 27 / 21
Olympics 5000' Temperature Forecast
(Max / Min)
Thursday Night 20 / 17
Friday 25 / 17
West North 5000' Temperature Forecast
(Max / Min)
Thursday Night 19 / 16
Friday 24 / 18
West Central 5000' Temperature Forecast
(Max / Min)
Thursday Night 20 / 17
Friday 25 / 18
West South 5000' Temperature Forecast
(Max / Min)
Thursday Night 21 / 19
Friday 27 / 19
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Thursday Night 21 / 17
Friday 25 / 16
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Thursday Night 20 / 17
Friday 25 / 17
East North 5000' Temperature Forecast
(Max / Min)
Thursday Night 16 / 11
Friday 21 / 12
East Central 5000' Temperature Forecast
(Max / Min)
Thursday Night 21 / 16
Friday 23 / 16
East South 5000' Temperature Forecast
(Max / Min)
Thursday Night 20 / 17
Friday 25 / 18
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Thursday Night 23 / 20
Friday 27 / 21

Issued: 2:03 PM PST Thursday, December 23, 2021

Ridgeline Winds (mph)

Thursday Evening Thursday Night Friday Morning Friday Afternoon
Olympics SW 10-20 SSW 15-25 S 5-15 S 5-15
West North WSW 10-20 S 20-30 S 10-20 SE 5-15
West Central W 15-25 SSW 20-30 S 10-20 S 5-15
West South W 15-25 SW 25-35 SW 15-25 SSW 10-20
Stevens Pass WSW 20-30 SSW 5-15 SSE 5-15 SE 5-15
Snoqualmie Pass W 25-35 SSW 10-20 S 5-15 SE 5-15
East North WSW 15-25 SW 10-20 S 5-15 SW 5-15
East Central W 30-40 WSW 10-20 SSW 5-15 SSW 5-15
East South W 20-30 SW 15-25 SW 20-30 SW 15-25
Mt. Hood W 30-40 WSW 30-40 WSW 30-40 WSW 20-30
Olympics Ridgeline Winds (mph)
Thursday Evening SW 10-20
Thursday Night SSW 15-25
Friday Morning S 5-15
Friday Afternoon S 5-15
West North Ridgeline Winds (mph)
Thursday Evening WSW 10-20
Thursday Night S 20-30
Friday Morning S 10-20
Friday Afternoon SE 5-15
West Central Ridgeline Winds (mph)
Thursday Evening W 15-25
Thursday Night SSW 20-30
Friday Morning S 10-20
Friday Afternoon S 5-15
West South Ridgeline Winds (mph)
Thursday Evening W 15-25
Thursday Night SW 25-35
Friday Morning SW 15-25
Friday Afternoon SSW 10-20
Stevens Pass Ridgeline Winds (mph)
Thursday Evening WSW 20-30
Thursday Night SSW 5-15
Friday Morning SSE 5-15
Friday Afternoon SE 5-15
Snoqualmie Pass Ridgeline Winds (mph)
Thursday Evening W 25-35
Thursday Night SSW 10-20
Friday Morning S 5-15
Friday Afternoon SE 5-15
East North Ridgeline Winds (mph)
Thursday Evening WSW 15-25
Thursday Night SW 10-20
Friday Morning S 5-15
Friday Afternoon SW 5-15
East Central Ridgeline Winds (mph)
Thursday Evening W 30-40
Thursday Night WSW 10-20
Friday Morning SSW 5-15
Friday Afternoon SSW 5-15
East South Ridgeline Winds (mph)
Thursday Evening W 20-30
Thursday Night SW 15-25
Friday Morning SW 20-30
Friday Afternoon SW 15-25
Mt. Hood Ridgeline Winds (mph)
Thursday Evening W 30-40
Thursday Night WSW 30-40
Friday Morning WSW 30-40
Friday Afternoon WSW 20-30

Issued: 2:03 PM PST Thursday, December 23, 2021

Extended Weather Synopsis

The aforementioned low may become quasi-stationary and park off the central Washington coast Saturday night and Sunday. This is a pattern for tapering snowfall amounts from north to south across the region (and lowland snow on the west side) with the most low density fluff likely from Snoqualmie Pass and south to Mt Hood.  Snowfall looks likely to taper off into Monday as drier air moves in. 

Strong arctic high pressure will likely drive extremely cold air through the Fraser Valley and eventually through the Cascade gaps starting Sunday and through the middle of the week. Forecast models are advertising a significant cold outbreak for all areas. Mountain temperatures in the single digits will be common.  Northern areas may stay below zero for quite some time.   

Extended Snow Level (ft)

Saturday Night Sunday Sunday Night Monday *
West North 0 0 0 0
Snoqualmie Pass 0 0 0 0
Mt. Hood 500' 0 0 0
West North Elevation
Saturday Night 0'
Sunday 0'
Sunday Night 0'
Monday * 0'
Snoqualmie Pass Elevation
Saturday Night 0'
Sunday 0'
Sunday Night 0'
Monday * 0'
Mt. Hood Elevation
Saturday Night 500'
Sunday 0'
Sunday Night 0'
Monday * 0'

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

Previous forecast from Dec 23, 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’.