Issued: 2:03 PM PST Saturday, December 21, 2024
by Dennis D'Amico

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

Weather Synopsis

A frontal system is passing through the Cascades early this afternoon with a burst of heavier precipitation, snow levels around 4000-4500' and gusty ridgeline winds. This period of moderate/heavy precipitation will be short lived; both the precipitation and winds will taper off this evening, except over the northwest Cascades where moderate showers will linger longest including the Mt Baker area, where another 1/2 inch of water (6" above the rain/snow line) is likely.

Upper level ridging will briefly shift over the area later tonight through Sunday morning, but don't get used to the idea of dry weather.  Another frontal system will spread precipitation into the Olympics in the morning, and into the WA Cascades/Mt Hood in the early afternoon with another increase in ridgeline winds. 

There will be a warming trend for areas west of the Cascade crest, the Olympics and especially Mt Hood where rain should push above 6000' before sunset on Sunday. The Cascade Passes and east slopes of the Cascades will stay cooler, with Snoqualmie clutching onto 3000' snow levels thanks to persistent cool easterly flow early on in the storm.  Precipitation will become heavier in the late afternoon and evening as the front approaches.  A trailing upper level trough will pass through after midnight, helping push out the colder air along the east slopes and bringing about a more uniform 4000-4500' snow level across the area as the precipitation becomes showery after midnight.  

Light showers will linger into Monday morning as transitory ridge builds over the inland NW, allowing us to dry out in the afternoon.  

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 Night Mostly cloudy with scattered light rain and snow showers in the evening. Periods of moderate ridgeline winds.
Sunday Light rain and snow developing in the morning, becoming heavier mid-day. Heaviest precipitation SW slopes of the Olympics. Strong winds.
Saturday Night Cloudy with light to moderate rain and snow showers in the evening then mostly cloudy with light showers tapering off after midnight. Periods of moderate ridgeline winds.
Sunday Cloudy with light rain and snow developing mid-day, and becoming light to moderate in the afternoon. Winds becoming strong in the afternoon.
Saturday Night Mostly cloudy with light rain and snow showers in the evening then showers tapering off after midnight. Periods of moderate ridgeline winds.
Sunday Cloudy with light rain and snow developing mid-day, and becoming light to occasionally moderate in the afternoon. Winds becoming moderate in the afternoon.
Saturday Night Mostly cloudy with scattered light rain and snow showers in the evening. Periods of moderate ridgeline winds.
Sunday Cloudy with light rain and snow developing mid to late morning, and becoming light to moderate in the afternoon. Winds becoming moderate to strong in the afternoon.
Saturday Night Mostly cloudy with scattered light rain and snow showers in the evening. Moderate W ridgeline and Pass level winds decreasing after midnight.
Sunday Cloudy with light rain and snow developing late morning to mid-day, and becoming light to occasionally moderate in the afternoon. SE ridgeline winds increasing and becoming moderate in the afternoon. Light to moderate E winds at Pass level.
Saturday Night Mostly cloudy with scattered light rain and snow showers in the evening. Moderate W ridgeline and Pass level winds decreasing after midnight.
Sunday Cloudy with light rain and snow developing late morning to mid-day, and becoming light to occasionally moderate in the afternoon. SE ridgeline winds increasing and becoming moderate in the afternoon. Moderate E winds at Pass level.
Saturday Night Mostly cloudy with scattered light rain and snow showers in the evening. Periods of moderate ridgeline winds.
Sunday Cloudy with light rain and snow developing midday, and becoming light to occasionally moderate late in the afternoon. Winds becoming moderate in the afternoon.
Saturday Night Mostly cloudy with scattered light rain and snow showers in the evening. Moderate ridgeline winds in the evening, then becoming lighter after midnight.
Sunday Cloudy with light rain and snow developing mid to late morning, and becoming light to occasionally moderate in the afternoon. Winds becoming moderate in the afternoon.
Saturday Night Mostly cloudy with scattered light rain and snow showers in the evening. Periods of moderate ridgeline winds.
Sunday Cloudy with light rain and snow developing mid to late morning, and becoming light to occasionally moderate in the afternoon. Winds becoming moderate in the afternoon.
Saturday Night Mostly cloudy with scattered light rain and snow showers in the evening. Periods of moderate ridgeline winds.
Sunday Cloudy with light rain and snow developing mid to late morning, and becoming light to occasionally moderate in the afternoon. Winds becoming moderate in the afternoon.

Issued: 2:03 PM PST Saturday, December 21, 2024

Precipitation (in)

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

Issued: 2:03 PM PST Saturday, December 21, 2024

Snow Level (ft)

Saturday Evening Saturday Night* Sunday Morning* Sunday Afternoon* Sunday Evening* Sunday Night Monday Morning Monday Afternoon*
Olympics 4000' 4000' 4500' 5000' 5500' 4500' 4000' 5000'
West North 3500' 3000' 3500' 3500' 4500' 4000' 4000' 4000'
West Central 3500' 3000' 3500' 3500' 4500' 4000' 4000' 4500'
West South 3500' 3000' 5000' 4000' 4500' 4500' 4000' 4500'
Stevens Pass 3500' 3000' 3500' 3000' 3000' 4000' 4000' 4000'
Snoqualmie Pass 4000' 3500' 4500' 3000' 3000' 4000' 4000' 4500'
East North 3500' 2000' 2500' 3000' 2500' 3000' 4000' 4000'
East Central 3500' 3000' 3500' 3000' 3000' 4000' 4000' 4000'
East South 3500' 3000' 3500' 3500' 3000' 4500' 4000' 5000'
Mt. Hood 4500' 5000' 5000' 6500' 6500' 4500' 4000' 7000'
Olympics Elevation
Saturday Evening 4000'
Saturday Night* 4000'
Sunday Morning* 4500'
Sunday Afternoon* 5000'
Sunday Evening* 5500'
Sunday Night 4500'
Monday Morning 4000'
Monday Afternoon* 5000'
West North Elevation
Saturday Evening 3500'
Saturday Night* 3000'
Sunday Morning* 3500'
Sunday Afternoon* 3500'
Sunday Evening* 4500'
Sunday Night 4000'
Monday Morning 4000'
Monday Afternoon* 4000'
West Central Elevation
Saturday Evening 3500'
Saturday Night* 3000'
Sunday Morning* 3500'
Sunday Afternoon* 3500'
Sunday Evening* 4500'
Sunday Night 4000'
Monday Morning 4000'
Monday Afternoon* 4500'
West South Elevation
Saturday Evening 3500'
Saturday Night* 3000'
Sunday Morning* 5000'
Sunday Afternoon* 4000'
Sunday Evening* 4500'
Sunday Night 4500'
Monday Morning 4000'
Monday Afternoon* 4500'
Stevens Pass Elevation
Saturday Evening 3500'
Saturday Night* 3000'
Sunday Morning* 3500'
Sunday Afternoon* 3000'
Sunday Evening* 3000'
Sunday Night 4000'
Monday Morning 4000'
Monday Afternoon* 4000'
Snoqualmie Pass Elevation
Saturday Evening 4000'
Saturday Night* 3500'
Sunday Morning* 4500'
Sunday Afternoon* 3000'
Sunday Evening* 3000'
Sunday Night 4000'
Monday Morning 4000'
Monday Afternoon* 4500'
East North Elevation
Saturday Evening 3500'
Saturday Night* 2000'
Sunday Morning* 2500'
Sunday Afternoon* 3000'
Sunday Evening* 2500'
Sunday Night 3000'
Monday Morning 4000'
Monday Afternoon* 4000'
East Central Elevation
Saturday Evening 3500'
Saturday Night* 3000'
Sunday Morning* 3500'
Sunday Afternoon* 3000'
Sunday Evening* 3000'
Sunday Night 4000'
Monday Morning 4000'
Monday Afternoon* 4000'
East South Elevation
Saturday Evening 3500'
Saturday Night* 3000'
Sunday Morning* 3500'
Sunday Afternoon* 3500'
Sunday Evening* 3000'
Sunday Night 4500'
Monday Morning 4000'
Monday Afternoon* 5000'
Mt. Hood Elevation
Saturday Evening 4500'
Saturday Night* 5000'
Sunday Morning* 5000'
Sunday Afternoon* 6500'
Sunday Evening* 6500'
Sunday Night 4500'
Monday Morning 4000'
Monday Afternoon* 7000'

Issued: 2:03 PM PST Saturday, December 21, 2024

5000' Temperatures (°F)

Saturday Night Sunday
Max / Min Max / Min
Olympics 29 / 25 33 / 29
West North 31 / 24 31 / 25
West Central 30 / 23 30 / 26
West South 29 / 24 33 / 26
Stevens Pass 30 / 22 29 / 25
Snoqualmie Pass 30 / 22 29 / 24
East North 29 / 21 26 / 21
East Central 29 / 22 30 / 24
East South 28 / 22 31 / 25
Mt. Hood 30 / 27 36 / 28
Olympics 5000' Temperature Forecast
(Max / Min)
Saturday Night 29 / 25
Sunday 33 / 29
West North 5000' Temperature Forecast
(Max / Min)
Saturday Night 31 / 24
Sunday 31 / 25
West Central 5000' Temperature Forecast
(Max / Min)
Saturday Night 30 / 23
Sunday 30 / 26
West South 5000' Temperature Forecast
(Max / Min)
Saturday Night 29 / 24
Sunday 33 / 26
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Saturday Night 30 / 22
Sunday 29 / 25
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Saturday Night 30 / 22
Sunday 29 / 24
East North 5000' Temperature Forecast
(Max / Min)
Saturday Night 29 / 21
Sunday 26 / 21
East Central 5000' Temperature Forecast
(Max / Min)
Saturday Night 29 / 22
Sunday 30 / 24
East South 5000' Temperature Forecast
(Max / Min)
Saturday Night 28 / 22
Sunday 31 / 25
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Saturday Night 30 / 27
Sunday 36 / 28

Issued: 2:03 PM PST Saturday, December 21, 2024

Ridgeline Winds (mph)

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

Issued: 2:03 PM PST Saturday, December 21, 2024

Extended Weather Synopsis

The fun really starts next week with a parade of weather systems arriving every 24 hours with some heavier atmospheric river event possible mid/later week.  The next frontal system will arrive Monday night into Tuesday and an even stronger more bellicose system is possible Christmas afternoon or night.  

Extended Snow Level (ft)

Monday Night* Tuesday Tuesday Night Wednesday *
West North 3000' 3500' 2000' 2500'
Snoqualmie Pass 3000' 3000' 2000' 3000'
Mt. Hood 6500' 4000' 2500' 3000'
West North Elevation
Monday Night* 3000'
Tuesday 3500'
Tuesday Night 2000'
Wednesday * 2500'
Snoqualmie Pass Elevation
Monday Night* 3000'
Tuesday 3000'
Tuesday Night 2000'
Wednesday * 3000'
Mt. Hood Elevation
Monday Night* 6500'
Tuesday 4000'
Tuesday Night 2500'
Wednesday * 3000'

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

Previous forecast from Dec 21, 2024

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’.