Issued: 1:45 PM PST Monday, December 13, 2021
by Dallas Glass

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

Weather Synopsis

Our unsettled weather will continue throughout the forecast period as several rounds of snow showers sweep across the area. This evening expect light snowfall to continue for most locations on both sides of the Cascade Crest. The low-pressure system responsible for our recent snow will finally approach the Olympic peninsula overnight. As it does so it should reinvigorate showers especially for locations along the western slopes of the Cascades from Mt Baker to White Pass. Look for ridgetop winds to back from east to southwest overnight as precipitation intensifies. Wind speeds and snowfall should peak Tuesday morning and into the early afternoon as the low slowly meanders its way onshore. Cold air already in place should make this an entirely snow event for mountain trailhead locations, with modest water amounts producing several inches of snow. 

By Tuesday evening we should see a slight break in the weather. Very cold air, westerly winds, and scattered showers will prevail overnight. On Wednesday another low-pressure system will begin to approach the coast spreading clouds and eventually snow across the mountains. There's some uncertainty about the timing of this storm and how much precipitation it will bring with it. What does feel confident is that with snow levels near or below 500ft, any precipitation that falls will be as snow. Expect showers to intensify in the afternoon and evening as this storm begins to impact the region. 

 

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
Monday Night Scattered snow showers. Moderate S winds.
Tuesday Isolated snow showers. Winds becoming SW and light.
Monday Night Snow showers could be moderate at times. Moderate to strong S winds.
Tuesday Snow showers. Winds becoming SW and decreasing.
Monday Night Snow showers could be moderate at times. Moderate SW winds.
Tuesday Snow showers with the possibility of a weak Puget Sound Convergence Zone in the afternoon. Light to moderate SW winds.
Monday Night Scattered snow showers. Heaviest near the volanoes. Moderate SW winds.
Tuesday Scattered snow showers. Moderate SW winds.
Monday Night Scattered snow showers. Light easterly flow becoming westerly overnight.
Tuesday Scattered snow showers with the possibility of a weak Puget Sound Convergence Zone in the afternoon. Light WSW winds.
Monday Night Scattered snow showers. Light easterly flow becoming westerly and increasing.
Tuesday Snow showers. Light W winds increasing in the afternoon.
Monday Night Scattered snow showers. Light to moderate SE winds backing to WSW.
Tuesday Isolated snow showers. Light SW winds.
Monday Night Snow showers in the evening, becoming isolated overnight. Moderate SW winds.
Tuesday Isolated snow showers heavies near the Cascade crest. W winds becoming strong in the afternoon.
Monday Night Snow showers in the evening, becoming isolated overnight. Moderate SW winds increasing slightly overnight.
Tuesday Isolated snow showers mainly near the crest. Strong W winds increasing slightly in the afternoon.
Monday Night Snow showers in the evening. Strong SW winds.
Tuesday Isolated snow showers. Very strong W winds decreasing slightly in the afternoon.

Issued: 1:45 PM PST Monday, December 13, 2021

Precipitation (in)

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

Issued: 1:45 PM PST Monday, December 13, 2021

Snow Level (ft)

Monday Evening* Monday Night Tuesday Morning Tuesday Afternoon Tuesday Evening Tuesday Night* Wednesday Morning* Wednesday Afternoon*
Olympics 2000' 1000' 1000' 1000' 500' 1000' 1000' 2000'
West North 2000' 1000' 500' 500' 500' 500' 500' 1000'
West Central 2000' 1000' 500' 1000' 500' 500' 500' 1000'
West South 2000' 1000' 500' 1000' 500' 500' 500' 1000'
Stevens Pass 2000' 1000' 500' 1000' 500' 500' 500' 1000'
Snoqualmie Pass 2500' 1000' 500' 1000' 500' 500' 500' 1000'
East North 2000' 1000' 500' 500' 500' 500' 500' 500'
East Central 2000' 1000' 500' 1000' 500' 500' 500' 1000'
East South 2000' 1000' 500' 1000' 500' 500' 500' 1000'
Mt. Hood 2000' 1000' 500' 1000' 500' 500' 500' 2000'
Olympics Elevation
Monday Evening* 2000'
Monday Night 1000'
Tuesday Morning 1000'
Tuesday Afternoon 1000'
Tuesday Evening 500'
Tuesday Night* 1000'
Wednesday Morning* 1000'
Wednesday Afternoon* 2000'
West North Elevation
Monday Evening* 2000'
Monday Night 1000'
Tuesday Morning 500'
Tuesday Afternoon 500'
Tuesday Evening 500'
Tuesday Night* 500'
Wednesday Morning* 500'
Wednesday Afternoon* 1000'
West Central Elevation
Monday Evening* 2000'
Monday Night 1000'
Tuesday Morning 500'
Tuesday Afternoon 1000'
Tuesday Evening 500'
Tuesday Night* 500'
Wednesday Morning* 500'
Wednesday Afternoon* 1000'
West South Elevation
Monday Evening* 2000'
Monday Night 1000'
Tuesday Morning 500'
Tuesday Afternoon 1000'
Tuesday Evening 500'
Tuesday Night* 500'
Wednesday Morning* 500'
Wednesday Afternoon* 1000'
Stevens Pass Elevation
Monday Evening* 2000'
Monday Night 1000'
Tuesday Morning 500'
Tuesday Afternoon 1000'
Tuesday Evening 500'
Tuesday Night* 500'
Wednesday Morning* 500'
Wednesday Afternoon* 1000'
Snoqualmie Pass Elevation
Monday Evening* 2500'
Monday Night 1000'
Tuesday Morning 500'
Tuesday Afternoon 1000'
Tuesday Evening 500'
Tuesday Night* 500'
Wednesday Morning* 500'
Wednesday Afternoon* 1000'
East North Elevation
Monday Evening* 2000'
Monday Night 1000'
Tuesday Morning 500'
Tuesday Afternoon 500'
Tuesday Evening 500'
Tuesday Night* 500'
Wednesday Morning* 500'
Wednesday Afternoon* 500'
East Central Elevation
Monday Evening* 2000'
Monday Night 1000'
Tuesday Morning 500'
Tuesday Afternoon 1000'
Tuesday Evening 500'
Tuesday Night* 500'
Wednesday Morning* 500'
Wednesday Afternoon* 1000'
East South Elevation
Monday Evening* 2000'
Monday Night 1000'
Tuesday Morning 500'
Tuesday Afternoon 1000'
Tuesday Evening 500'
Tuesday Night* 500'
Wednesday Morning* 500'
Wednesday Afternoon* 1000'
Mt. Hood Elevation
Monday Evening* 2000'
Monday Night 1000'
Tuesday Morning 500'
Tuesday Afternoon 1000'
Tuesday Evening 500'
Tuesday Night* 500'
Wednesday Morning* 500'
Wednesday Afternoon* 2000'

Issued: 1:45 PM PST Monday, December 13, 2021

5000' Temperatures (°F)

Monday Night Tuesday
Max / Min Max / Min
Olympics 21 / 14 21 / 15
West North 26 / 13 19 / 13
West Central 25 / 11 19 / 13
West South 26 / 16 21 / 16
Stevens Pass 24 / 12 21 / 13
Snoqualmie Pass 24 / 11 21 / 14
East North 25 / 12 18 / 11
East Central 26 / 11 21 / 13
East South 26 / 12 20 / 14
Mt. Hood 22 / 15 21 / 14
Olympics 5000' Temperature Forecast
(Max / Min)
Monday Night 21 / 14
Tuesday 21 / 15
West North 5000' Temperature Forecast
(Max / Min)
Monday Night 26 / 13
Tuesday 19 / 13
West Central 5000' Temperature Forecast
(Max / Min)
Monday Night 25 / 11
Tuesday 19 / 13
West South 5000' Temperature Forecast
(Max / Min)
Monday Night 26 / 16
Tuesday 21 / 16
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Monday Night 24 / 12
Tuesday 21 / 13
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Monday Night 24 / 11
Tuesday 21 / 14
East North 5000' Temperature Forecast
(Max / Min)
Monday Night 25 / 12
Tuesday 18 / 11
East Central 5000' Temperature Forecast
(Max / Min)
Monday Night 26 / 11
Tuesday 21 / 13
East South 5000' Temperature Forecast
(Max / Min)
Monday Night 26 / 12
Tuesday 20 / 14
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Monday Night 22 / 15
Tuesday 21 / 14

Issued: 1:45 PM PST Monday, December 13, 2021

Ridgeline Winds (mph)

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

Issued: 1:45 PM PST Monday, December 13, 2021

Extended Weather Synopsis

With a storm already on our doorstep, the long-range forecast appears active. While the bulk of this system seems to head into Oregon, our mountain areas could see significant snowfalls, especially from Mt Rainier southward. By Thursday night and into Friday, steady snow finally turns to snow showers and gradual clearing. A fast-moving high-pressure ridge should provide a short-lived break ahead of what appears to be yet another storm on tap for the weekend. 

Extended Snow Level (ft)

Wednesday Night* Thursday Thursday Night Friday *
West North 500' 500' 500' 500'
Snoqualmie Pass 500' 1000' 1000' 1000'
Mt. Hood 1500' 2500' 2000' 2000'
West North Elevation
Wednesday Night* 500'
Thursday 500'
Thursday Night 500'
Friday * 500'
Snoqualmie Pass Elevation
Wednesday Night* 500'
Thursday 1000'
Thursday Night 1000'
Friday * 1000'
Mt. Hood Elevation
Wednesday Night* 1500'
Thursday 2500'
Thursday Night 2000'
Friday * 2000'

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

Previous forecast from Dec 13, 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’.