Issued: 2:07 PM PST Wednesday, December 11, 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 weakening Pacific frontal system is slowing and splitting apart as it approaches the coastline this afternoon. Part of the frontal system will slide into OR/CA overnight, perhaps clipping the Mt Hood area with light showers. Further north over the Washington Cascades and Olympics, we'll be left with partly cloudy skies, with areas of low clouds concentrated along the eastern slopes of the Cascades and the eastern approaches for the major Passes.  While this system isn't much to look at, it will increase offshore gradients and bring about moderate SE ridgeline winds that drag colder air across the Cascades along with lowering freezing levels. Areas further west, such as the Mt Baker area, will remain milder overnight. 

SE ridgeline winds will peak before sunrise, and then should back off and eventually become WSW in the afternoon as a longwave upper level trough passes through. This upper level feature should spread light showers throughout the area, and more uniformity in the snow levels over the mountains (3500-4500').  A few leftover showers may linger into Thursday night. 

A stronger system will approach on Friday.  This frontal system will be slow to spread precipitation inland, with light warm frontal precipitation moving over the Cascades later in the day. Strong S-SE ridgeline winds may really start to crank by the afternoon...there are still questions about the strength and timing with this system.  We'll see relatively higher snow levels, although not too high, west of the Cascade crest on Friday vs areas further east. 

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
Wednesday Night Partly cloudy, becoming cloudy late evening. Light to occasionally moderate ridgeline winds.
Thursday Cloudy with a chance of light rain and snow showers. Light to occasionally moderate ridgeline winds.
Wednesday Night Partly cloudy, becoming cloudy around midnight. Moderate ridgeline winds, becoming light to moderate after midnight.
Thursday Cloudy. Light to occasionally moderate ridgeline winds.
Wednesday Night Partly cloudy, then becoming cloudy late evening. Light to occasionally moderate ridgeline winds.
Thursday Cloudy. Light to occasionally moderate ridgeline winds.
Wednesday Night Partly cloudy, then becoming cloudy in the evening. Light to moderate ridgeline winds, increasing to moderate to locally strong after midnight.
Thursday Cloudy with a chance of light rain and snow showers. Light to occasionally moderate ridgeline winds.
Wednesday Night Partly cloudy, then becoming cloudy in the evening. Areas of low clouds mainly east of the Pass. Light to moderate E-SE Pass level and ridgeline winds increasing after midnight.
Thursday Cloudy with a chance of light rain and snow showers. Moderate E-SE ridgeline winds becoming W in the afternoon. Moderate E Pass level winds becoming light in the afternoon.
Wednesday Night Partly cloudy, then becoming cloudy in the evening. Areas of low clouds near and east of the Pass. Moderate E-SE Pass level and ridgeline winds increasing after midnight.
Thursday Cloudy with a chance of light rain and snow showers. Moderate E-SE ridgeline winds becoming W in the afternoon. Moderate E Pass level winds becoming light in the afternoon.
Wednesday Night Partly cloudy, then becoming cloudy after midnight. Areas of low clouds and fog lower slopes and valleys. Light to moderate ridgeline winds.
Thursday Cloudy with a chance of light snow showers. Light to occasionally moderate ridgeline winds.
Wednesday Night Partly cloudy, then becoming cloudy late in the evening. Areas of low clouds and fog lower slopes and valleys. Light to moderate ridgeline winds.
Thursday Cloudy with a chance of light snow showers. Light to occasionally moderate ridgeline winds.
Wednesday Night Partly cloudy, then becoming cloudy late in the evening. Areas of low clouds and fog lower slopes and valleys. Light to moderate ridgeline winds.
Thursday Cloudy with a chance of light snow showers. Light to occasionally moderate ridgeline winds.
Wednesday Night Partly cloudy, then becoming cloudy in the evening with a chance of light rain and snow. Light to moderate ridgeline winds.
Thursday Cloudy with scattered light rain and snow showers. Light to moderate ridgeline winds.

Precipitation (in)

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

Snow Level (ft)

Wednesday Evening* Wednesday Night* Thursday Morning* Thursday Afternoon* Thursday Evening* Thursday Night* Friday Morning* Friday Afternoon*
Olympics 6500' 6500' 5500' 4500' 4000' 4000' 4000' 4500'
West North 6500' 6500' 6000' 4500' 3500' 3500' 3500' 3500'
West Central 6500' 4500' 4000' 4000' 3500' 3000' 3000' 3500'
West South 6500' 3000' 3000' 4000' 3500' 3000' 3000' 4000'
Stevens Pass 3000' 2500' 2500' 3500' 3000' 2500' 2500' 2500'
Snoqualmie Pass 6500' 3000' 3000' 3500' 3000' 3000' 3000' 3000'
East North 2500' 1500' 2000' 3500' 2500' 2000' 2000' 2000'
East Central 2500' 1500' 2000' 3500' 2500' 2000' 2000' 2000'
East South 3000' 2000' 2500' 3500' 3000' 2500' 2500' 2500'
Mt. Hood 6500' 4500' 3000' 4000' 4000' 4000' 4000' 4500'
Olympics Elevation
Wednesday Evening* 6500'
Wednesday Night* 6500'
Thursday Morning* 5500'
Thursday Afternoon* 4500'
Thursday Evening* 4000'
Thursday Night* 4000'
Friday Morning* 4000'
Friday Afternoon* 4500'
West North Elevation
Wednesday Evening* 6500'
Wednesday Night* 6500'
Thursday Morning* 6000'
Thursday Afternoon* 4500'
Thursday Evening* 3500'
Thursday Night* 3500'
Friday Morning* 3500'
Friday Afternoon* 3500'
West Central Elevation
Wednesday Evening* 6500'
Wednesday Night* 4500'
Thursday Morning* 4000'
Thursday Afternoon* 4000'
Thursday Evening* 3500'
Thursday Night* 3000'
Friday Morning* 3000'
Friday Afternoon* 3500'
West South Elevation
Wednesday Evening* 6500'
Wednesday Night* 3000'
Thursday Morning* 3000'
Thursday Afternoon* 4000'
Thursday Evening* 3500'
Thursday Night* 3000'
Friday Morning* 3000'
Friday Afternoon* 4000'
Stevens Pass Elevation
Wednesday Evening* 3000'
Wednesday Night* 2500'
Thursday Morning* 2500'
Thursday Afternoon* 3500'
Thursday Evening* 3000'
Thursday Night* 2500'
Friday Morning* 2500'
Friday Afternoon* 2500'
Snoqualmie Pass Elevation
Wednesday Evening* 6500'
Wednesday Night* 3000'
Thursday Morning* 3000'
Thursday Afternoon* 3500'
Thursday Evening* 3000'
Thursday Night* 3000'
Friday Morning* 3000'
Friday Afternoon* 3000'
East North Elevation
Wednesday Evening* 2500'
Wednesday Night* 1500'
Thursday Morning* 2000'
Thursday Afternoon* 3500'
Thursday Evening* 2500'
Thursday Night* 2000'
Friday Morning* 2000'
Friday Afternoon* 2000'
East Central Elevation
Wednesday Evening* 2500'
Wednesday Night* 1500'
Thursday Morning* 2000'
Thursday Afternoon* 3500'
Thursday Evening* 2500'
Thursday Night* 2000'
Friday Morning* 2000'
Friday Afternoon* 2000'
East South Elevation
Wednesday Evening* 3000'
Wednesday Night* 2000'
Thursday Morning* 2500'
Thursday Afternoon* 3500'
Thursday Evening* 3000'
Thursday Night* 2500'
Friday Morning* 2500'
Friday Afternoon* 2500'
Mt. Hood Elevation
Wednesday Evening* 6500'
Wednesday Night* 4500'
Thursday Morning* 3000'
Thursday Afternoon* 4000'
Thursday Evening* 4000'
Thursday Night* 4000'
Friday Morning* 4000'
Friday Afternoon* 4500'

5000' Temperatures (°F)

Wednesday Night Thursday
Max / Min Max / Min
Olympics 31 / 29 34 / 31
West North 30 / 28 34 / 31
West Central 30 / 27 31 / 27
West South 30 / 26 32 / 26
Stevens Pass 24 / 23 28 / 25
Snoqualmie Pass 26 / 24 29 / 25
East North 22 / 20 27 / 21
East Central 25 / 22 28 / 22
East South 27 / 23 30 / 24
Mt. Hood 32 / 28 34 / 28
Olympics 5000' Temperature Forecast
(Max / Min)
Wednesday Night 31 / 29
Thursday 34 / 31
West North 5000' Temperature Forecast
(Max / Min)
Wednesday Night 30 / 28
Thursday 34 / 31
West Central 5000' Temperature Forecast
(Max / Min)
Wednesday Night 30 / 27
Thursday 31 / 27
West South 5000' Temperature Forecast
(Max / Min)
Wednesday Night 30 / 26
Thursday 32 / 26
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Wednesday Night 24 / 23
Thursday 28 / 25
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Wednesday Night 26 / 24
Thursday 29 / 25
East North 5000' Temperature Forecast
(Max / Min)
Wednesday Night 22 / 20
Thursday 27 / 21
East Central 5000' Temperature Forecast
(Max / Min)
Wednesday Night 25 / 22
Thursday 28 / 22
East South 5000' Temperature Forecast
(Max / Min)
Wednesday Night 27 / 23
Thursday 30 / 24
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Wednesday Night 32 / 28
Thursday 34 / 28

Ridgeline Winds (mph)

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

Extended Weather Synopsis

The associated cold front will pass through Friday night followed by showers on Saturday.  This should deliver at least a modest amount of snow to the mountains with snow levels between 2000-3500' over the WA Cascades and Olympics, and slightly warmer conditions down near Mt Hood. More scattered showers will likely follow Saturday night and Sunday, but stay tuned as forecast models really start to diverge over the latter half of the weekend. 

Extended Snow Level (ft)

Friday Night* Saturday * Saturday Night* Sunday *
West North 3000' 3500' 1500' 2000'
Snoqualmie Pass 3000' 3500' 2000' 2500'
Mt. Hood 4500' 4000' 2500' 1500'
West North Elevation
Friday Night* 3000'
Saturday * 3500'
Saturday Night* 1500'
Sunday * 2000'
Snoqualmie Pass Elevation
Friday Night* 3000'
Saturday * 3500'
Saturday Night* 2000'
Sunday * 2500'
Mt. Hood Elevation
Friday Night* 4500'
Saturday * 4000'
Saturday Night* 2500'
Sunday * 1500'

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

Previous forecast from Dec 11, 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’.