Issued: 1:59 PM PST Sunday, November 21, 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

It's a mild Sunday afternoon in the mountains with temperatures in the mid 30s to mid 40s from the Canadian border to Mt Hood under partly sunny skies.  The upper level ridge responsible for the dry and mild weather on Sunday will migrate inland Sunday night.  A low pressure system winding into the central/northern B.C. coast Sunday night will bring increasing clouds from NW to SE across the region on Monday along with light precipitation (mostly rain) to the Olympics and northwest Cascades by mid-day. 

The frontal band is forecast to move through Monday evening with a widespread burst of light to moderate precipitation across the area. The trailing shortwave trough behind the frontal boundary will likely inject additional moisture into the area in the form of showers through much of Tuesday.  Snow levels will fall rapidly with the upper trough on Tuesday morning with accumulating snow at 3000' or lower by daybreak.  Winds will become brisk out of the WNW late Monday night through Tuesday and a Puget Sound Convergence Zone is likely to form in the central Cascades as well. 

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
Sunday Night Partly cloudy to mostly clear with periods of high clouds.
Monday Mostly cloudy in the morning. Becoming cloudy mid-day with light rain and snow developing. Moderate to strong winds developing.
Sunday Night Partly cloudy to mostly clear with periods of high clouds.
Monday Mostly cloudy in the morning. Becoming cloudy mid-day with light rain and snow developing. Strong winds.
Sunday Night Partly cloudy to mostly clear with periods of high clouds.
Monday Partly to mostly cloudy in the morning. Becoming cloudy in mid-day with light rain and snow developing in the afternoon.
Sunday Night Partly cloudy to mostly clear with periods of high clouds.
Monday Mostly sunny in the morning then becoming mostly cloudy in the afternoon.
Sunday Night Partly cloudy to mostly clear with periods of high clouds. Light east winds at Pass level.
Monday Partly to mostly cloudy in the morning then becoming cloudy in the afternoon. Light east winds at Pass level.
Sunday Night Partly cloudy to mostly clear with periods of high clouds. Light to moderate east winds at Pass level.
Monday Partly sunny in the morning then becoming cloudy in the afternoon. Light east winds at Pass level.
Sunday Night Partly cloudy to mostly clear with periods of high clouds.
Monday Partly sunny in the morning then becoming cloudy in the afternoon. Chance of light rain or snow late.
Sunday Night Partly cloudy to mostly clear with periods of high clouds.
Monday Mostly sunny in the morning then becoming mostly cloudy in the afternoon.
Sunday Night Partly cloudy to mostly clear with periods of high clouds.
Monday Mostly sunny in the morning then becoming partly cloudy in the afternoon.
Sunday Night Partly cloudy to mostly clear with periods of high clouds.
Monday Mostly sunny in the morning then becoming partly cloudy in the afternoon.

Issued: 1:59 PM PST Sunday, November 21, 2021

Precipitation (in)

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

Issued: 1:59 PM PST Sunday, November 21, 2021

Snow Level (ft)

Sunday Evening Sunday Night Monday Morning Monday Afternoon Monday Evening Monday Night Tuesday Morning Tuesday Afternoon
Olympics 10000' 9000' 7500' 5000' 3500' 3000' 2500' 2500'
West North 7500' 7000' 6500' 5000' 3500' 3000' 2500' 2500'
West Central 8500' 8500' 7500' 6000' 3500' 3000' 2500' 2500'
West South 11000' 9000' 7500' 7000' 4000' 3000' 2500' 2500'
Stevens Pass 9000' 9000' 8000' 7000' 3500' 3000' 2500' 2500'
Snoqualmie Pass 10000' 9000' 8000' 7000' 3500' 3000' 2500' 2500'
East North 8000' 8000' 7500' 5000' 3000' 3000' 2500' 2000'
East Central 8500' 8000' 8000' 6000' 4000' 3000' 2500' 2500'
East South 10000' 9000' 9000' 8000' 4000' 3500' 3000' 2500'
Mt. Hood 12000' 11000' 10000' 9000' 4500' 3500' 3500' 3000'
Olympics Elevation
Sunday Evening 10000'
Sunday Night 9000'
Monday Morning 7500'
Monday Afternoon 5000'
Monday Evening 3500'
Monday Night 3000'
Tuesday Morning 2500'
Tuesday Afternoon 2500'
West North Elevation
Sunday Evening 7500'
Sunday Night 7000'
Monday Morning 6500'
Monday Afternoon 5000'
Monday Evening 3500'
Monday Night 3000'
Tuesday Morning 2500'
Tuesday Afternoon 2500'
West Central Elevation
Sunday Evening 8500'
Sunday Night 8500'
Monday Morning 7500'
Monday Afternoon 6000'
Monday Evening 3500'
Monday Night 3000'
Tuesday Morning 2500'
Tuesday Afternoon 2500'
West South Elevation
Sunday Evening 11000'
Sunday Night 9000'
Monday Morning 7500'
Monday Afternoon 7000'
Monday Evening 4000'
Monday Night 3000'
Tuesday Morning 2500'
Tuesday Afternoon 2500'
Stevens Pass Elevation
Sunday Evening 9000'
Sunday Night 9000'
Monday Morning 8000'
Monday Afternoon 7000'
Monday Evening 3500'
Monday Night 3000'
Tuesday Morning 2500'
Tuesday Afternoon 2500'
Snoqualmie Pass Elevation
Sunday Evening 10000'
Sunday Night 9000'
Monday Morning 8000'
Monday Afternoon 7000'
Monday Evening 3500'
Monday Night 3000'
Tuesday Morning 2500'
Tuesday Afternoon 2500'
East North Elevation
Sunday Evening 8000'
Sunday Night 8000'
Monday Morning 7500'
Monday Afternoon 5000'
Monday Evening 3000'
Monday Night 3000'
Tuesday Morning 2500'
Tuesday Afternoon 2000'
East Central Elevation
Sunday Evening 8500'
Sunday Night 8000'
Monday Morning 8000'
Monday Afternoon 6000'
Monday Evening 4000'
Monday Night 3000'
Tuesday Morning 2500'
Tuesday Afternoon 2500'
East South Elevation
Sunday Evening 10000'
Sunday Night 9000'
Monday Morning 9000'
Monday Afternoon 8000'
Monday Evening 4000'
Monday Night 3500'
Tuesday Morning 3000'
Tuesday Afternoon 2500'
Mt. Hood Elevation
Sunday Evening 12000'
Sunday Night 11000'
Monday Morning 10000'
Monday Afternoon 9000'
Monday Evening 4500'
Monday Night 3500'
Tuesday Morning 3500'
Tuesday Afternoon 3000'

Issued: 1:59 PM PST Sunday, November 21, 2021

5000' Temperatures (°F)

Sunday Night Monday
Max / Min Max / Min
Olympics 40 / 34 34 / 32
West North 37 / 35 35 / 29
West Central 38 / 36 36 / 31
West South 40 / 38 41 / 35
Stevens Pass 38 / 36 38 / 33
Snoqualmie Pass 39 / 36 38 / 33
East North 36 / 33 37 / 31
East Central 40 / 36 39 / 34
East South 41 / 38 42 / 35
Mt. Hood 41 / 38 45 / 39
Olympics 5000' Temperature Forecast
(Max / Min)
Sunday Night 40 / 34
Monday 34 / 32
West North 5000' Temperature Forecast
(Max / Min)
Sunday Night 37 / 35
Monday 35 / 29
West Central 5000' Temperature Forecast
(Max / Min)
Sunday Night 38 / 36
Monday 36 / 31
West South 5000' Temperature Forecast
(Max / Min)
Sunday Night 40 / 38
Monday 41 / 35
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Sunday Night 38 / 36
Monday 38 / 33
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Sunday Night 39 / 36
Monday 38 / 33
East North 5000' Temperature Forecast
(Max / Min)
Sunday Night 36 / 33
Monday 37 / 31
East Central 5000' Temperature Forecast
(Max / Min)
Sunday Night 40 / 36
Monday 39 / 34
East South 5000' Temperature Forecast
(Max / Min)
Sunday Night 41 / 38
Monday 42 / 35
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Sunday Night 41 / 38
Monday 45 / 39

Issued: 1:59 PM PST Sunday, November 21, 2021

Ridgeline Winds (mph)

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

Issued: 1:59 PM PST Sunday, November 21, 2021

Extended Weather Synopsis

We'll see shortwave ridging move Tuesday night and Wednesday, allowing dry conditions to take hold over the area.  A stronger, wetter system will take aim at the Pacific Northwest Wednesday night first for the north Cascades and Olympics and shift south on Thanksgiving.  The jet stream, the dividing line between warm and relatively colder air masses, looks like it will be aimed near the Canadian border for much of this event.  Snow levels look fairly high in the central/south Washington Cascades and northern Oregon.  We'll have to wait and see if there will be significant snow accumulations in the north Cascades (both sides of the crest) and just how high snow levels will push during this event.    

Extended Snow Level (ft)

Tuesday Night Wednesday Wednesday Night Thursday
West North 1500' 2500' 2500' 4000'
Snoqualmie Pass 1500' 3000' 4500' 6500'
Mt. Hood 2000' 4500' 8000' 8500'
West North Elevation
Tuesday Night 1500'
Wednesday 2500'
Wednesday Night 2500'
Thursday 4000'
Snoqualmie Pass Elevation
Tuesday Night 1500'
Wednesday 3000'
Wednesday Night 4500'
Thursday 6500'
Mt. Hood Elevation
Tuesday Night 2000'
Wednesday 4500'
Wednesday Night 8000'
Thursday 8500'

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

Previous forecast from Nov 20, 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’.