Issued: 2:14 PM PST Saturday, November 20, 2021
by Robert Hahn

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

Weather Synopsis

High pressure expanding into the region provides the Pacific Northwest with a break from an otherwise very active fall weather pattern.

Cool air continues to hold on over the Pacific Northwest Saturday night. However, the expanding high should spread warm air into mid and upper elevation locations with the warm-up occurring earlier across the Southern Cascades. A period of low-level E wind develops Saturday evening as the ridge of high pressure shifts eastward. Cooler air hanging on at low elevations east of the Cascade Crest and migrating through the Passes will create a temperature inversion as warm air rides over the top. Expect these inversions to break down during the late morning to mid-afternoon afternoon hours, resulting in a shift from below-freezing to well-above-freezing temperatures in many cases. Downslope winds should prevent inversions from forming west of the Cascade Crest and allow for much warmer conditions Saturday night into Sunday. Washington Pass may be able to avoid most of the above freezing temperatures, but most other locations below 9000 ft will not.

Sunday night will be mostly clear and mild with gradually lowering freezing levels. Low-level winds peak due to the rapid deepening of a low tracking towards the N tip of Vancouver Island as upper-level wind increases from the WSW. The associated cold front approaches with lowering clouds followed by light rain and high elevation snow to the Olympics Monday afternoon and perhaps the west slopes of the Cascades late in the day.

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 clear. Increasing shallow inversion with fog developing in valleys.
Sunday Filtered sunshine. Rapidly rising freezing levels.
Saturday Night Mostly clear. Increasing shallow inversion with fog developing in valleys.
Sunday Filtered sunshine. Rapidly rising freezing levels.
Saturday Night Mostly clear. Increasing shallow inversion with fog developing in valleys.
Sunday Filtered sunshine. Rapidly rising freezing levels.
Saturday Night Mostly clear. Increasing shallow inversion with fog developing in valleys.
Sunday Filtered sunshine. Rapidly rising freezing levels.
Saturday Night Mostly clear. Increasing shallow inversion with fog developing in valleys. Light pass-level E wind developing and increasing overnight.
Sunday Filtered sunshine. Rapidly rising freezing levels. Light to occasionally moderate E wind at the Pass.
Saturday Night Mostly clear. Increasing shallow inversion with fog developing in valleys. Light pass-level E wind developing and becoming light to moderate overnight.
Sunday Filtered sunshine. Rapidly rising freezing levels. Light to occasionally moderate E wind at the Pass.
Saturday Night Mostly clear. Increasing shallow inversion with fog developing in valleys.
Sunday Filtered sunshine. Rapidly rising freezing levels.
Saturday Night Mostly clear. Rising temperatures at elevations above a shallow inversion layer. Fog possible in valleys.
Sunday Filtered sunshine. Rapidly rising freezing levels.
Saturday Night Mostly clear. Rising temperatures at elevations above a shallow inversion layer. Fog possible in valleys.
Sunday Filtered sunshine. Rapidly rising freezing levels.
Saturday Night Mostly clear. Rising temperatures at elevations above a shallow inversion layer. Fog possible in valleys.
Sunday Filtered sunshine. Rapidly rising freezing levels.

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

Snow Level (ft)

Saturday Evening Saturday Night* Sunday Morning* Sunday Afternoon* Sunday Evening* Sunday Night* Monday Morning* Monday Afternoon*
Olympics 3500' 4000' 6000' 10000' 11500' 10500' 8500' 6500'
West North 3000' 3000' 4000' 7000' 8000' 9500' 8500' 6500'
West Central 3500' 3000' 4000' 8500' 9000' 9000' 8000' 7000'
West South 4000' 4500' 5500' 10000' 10500' 10000' 8000' 8000'
Stevens Pass 3000' 3000' 3500' 8500' 7500' 6000' 5000' 8500'
Snoqualmie Pass 3500' 3500' 4500' 9000' 8500' 7000' 6500' 8500'
East North 3000' 2500' 2500' 7000' 5500' 5500' 4500' 7500'
East Central 3000' 3500' 3500' 9000' 6000' 5500' 5000' 8500'
East South 3500' 4500' 4500' 10500' 8500' 7000' 6000' 10000'
Mt. Hood 6000' 7000' 9000' 11000' 12000' 12500' 12000' 10500'
Olympics Elevation
Saturday Evening 3500'
Saturday Night* 4000'
Sunday Morning* 6000'
Sunday Afternoon* 10000'
Sunday Evening* 11500'
Sunday Night* 10500'
Monday Morning* 8500'
Monday Afternoon* 6500'
West North Elevation
Saturday Evening 3000'
Saturday Night* 3000'
Sunday Morning* 4000'
Sunday Afternoon* 7000'
Sunday Evening* 8000'
Sunday Night* 9500'
Monday Morning* 8500'
Monday Afternoon* 6500'
West Central Elevation
Saturday Evening 3500'
Saturday Night* 3000'
Sunday Morning* 4000'
Sunday Afternoon* 8500'
Sunday Evening* 9000'
Sunday Night* 9000'
Monday Morning* 8000'
Monday Afternoon* 7000'
West South Elevation
Saturday Evening 4000'
Saturday Night* 4500'
Sunday Morning* 5500'
Sunday Afternoon* 10000'
Sunday Evening* 10500'
Sunday Night* 10000'
Monday Morning* 8000'
Monday Afternoon* 8000'
Stevens Pass Elevation
Saturday Evening 3000'
Saturday Night* 3000'
Sunday Morning* 3500'
Sunday Afternoon* 8500'
Sunday Evening* 7500'
Sunday Night* 6000'
Monday Morning* 5000'
Monday Afternoon* 8500'
Snoqualmie Pass Elevation
Saturday Evening 3500'
Saturday Night* 3500'
Sunday Morning* 4500'
Sunday Afternoon* 9000'
Sunday Evening* 8500'
Sunday Night* 7000'
Monday Morning* 6500'
Monday Afternoon* 8500'
East North Elevation
Saturday Evening 3000'
Saturday Night* 2500'
Sunday Morning* 2500'
Sunday Afternoon* 7000'
Sunday Evening* 5500'
Sunday Night* 5500'
Monday Morning* 4500'
Monday Afternoon* 7500'
East Central Elevation
Saturday Evening 3000'
Saturday Night* 3500'
Sunday Morning* 3500'
Sunday Afternoon* 9000'
Sunday Evening* 6000'
Sunday Night* 5500'
Monday Morning* 5000'
Monday Afternoon* 8500'
East South Elevation
Saturday Evening 3500'
Saturday Night* 4500'
Sunday Morning* 4500'
Sunday Afternoon* 10500'
Sunday Evening* 8500'
Sunday Night* 7000'
Monday Morning* 6000'
Monday Afternoon* 10000'
Mt. Hood Elevation
Saturday Evening 6000'
Saturday Night* 7000'
Sunday Morning* 9000'
Sunday Afternoon* 11000'
Sunday Evening* 12000'
Sunday Night* 12500'
Monday Morning* 12000'
Monday Afternoon* 10500'

5000' Temperatures (°F)

Saturday Night Sunday
Max / Min Max / Min
Olympics 33 / 26 40 / 34
West North 27 / 24 38 / 28
West Central 28 / 25 39 / 29
West South 31 / 24 46 / 32
Stevens Pass 29 / 24 43 / 30
Snoqualmie Pass 29 / 25 39 / 30
East North 29 / 26 36 / 29
East Central 29 / 26 41 / 30
East South 30 / 27 44 / 31
Mt. Hood 34 / 30 46 / 34
Olympics 5000' Temperature Forecast
(Max / Min)
Saturday Night 33 / 26
Sunday 40 / 34
West North 5000' Temperature Forecast
(Max / Min)
Saturday Night 27 / 24
Sunday 38 / 28
West Central 5000' Temperature Forecast
(Max / Min)
Saturday Night 28 / 25
Sunday 39 / 29
West South 5000' Temperature Forecast
(Max / Min)
Saturday Night 31 / 24
Sunday 46 / 32
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Saturday Night 29 / 24
Sunday 43 / 30
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Saturday Night 29 / 25
Sunday 39 / 30
East North 5000' Temperature Forecast
(Max / Min)
Saturday Night 29 / 26
Sunday 36 / 29
East Central 5000' Temperature Forecast
(Max / Min)
Saturday Night 29 / 26
Sunday 41 / 30
East South 5000' Temperature Forecast
(Max / Min)
Saturday Night 30 / 27
Sunday 44 / 31
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Saturday Night 34 / 30
Sunday 46 / 34

Ridgeline Winds (mph)

Saturday Evening Saturday Night Sunday Morning Sunday Afternoon
Olympics WSW 0-10 SW 5-15 SW 10-20 SW 10-20
West North SW 0-10 SW 5-15 SW 10-20 SSW 10-20
West Central WNW 0-10 SW 5-15 SW 5-15 SSW 5-15
West South SW 0-10 SW 0-10 SW 0-10 SSW 0-10
Stevens Pass W 0-10 SW 0-10 SW 0-10 SW 0-10
Snoqualmie Pass NW 0-10 SW 0-10 SW 0-10 SW 0-10
East North W 5-15 WSW 5-15 WSW 10-20 SW 10-20
East Central WNW 5-15 WSW 10-20 W 10-20 WSW 10-20
East South WSW 0-10 SW 0-10 SW 0-10 SW 0-10
Mt. Hood NW 0-10 WSW 0-10 SSW 0-10 SW 0-10
Olympics Ridgeline Winds (mph)
Saturday Evening WSW 0-10
Saturday Night SW 5-15
Sunday Morning SW 10-20
Sunday Afternoon SW 10-20
West North Ridgeline Winds (mph)
Saturday Evening SW 0-10
Saturday Night SW 5-15
Sunday Morning SW 10-20
Sunday Afternoon SSW 10-20
West Central Ridgeline Winds (mph)
Saturday Evening WNW 0-10
Saturday Night SW 5-15
Sunday Morning SW 5-15
Sunday Afternoon SSW 5-15
West South Ridgeline Winds (mph)
Saturday Evening SW 0-10
Saturday Night SW 0-10
Sunday Morning SW 0-10
Sunday Afternoon SSW 0-10
Stevens Pass Ridgeline Winds (mph)
Saturday Evening W 0-10
Saturday Night SW 0-10
Sunday Morning SW 0-10
Sunday Afternoon SW 0-10
Snoqualmie Pass Ridgeline Winds (mph)
Saturday Evening NW 0-10
Saturday Night SW 0-10
Sunday Morning SW 0-10
Sunday Afternoon SW 0-10
East North Ridgeline Winds (mph)
Saturday Evening W 5-15
Saturday Night WSW 5-15
Sunday Morning WSW 10-20
Sunday Afternoon SW 10-20
East Central Ridgeline Winds (mph)
Saturday Evening WNW 5-15
Saturday Night WSW 10-20
Sunday Morning W 10-20
Sunday Afternoon WSW 10-20
East South Ridgeline Winds (mph)
Saturday Evening WSW 0-10
Saturday Night SW 0-10
Sunday Morning SW 0-10
Sunday Afternoon SW 0-10
Mt. Hood Ridgeline Winds (mph)
Saturday Evening NW 0-10
Saturday Night WSW 0-10
Sunday Morning SSW 0-10
Sunday Afternoon SW 0-10

Extended Weather Synopsis

The cold front arrives Monday evening, bringing rapid cooling to the region along with moderate rain/snow. Snow levels should drop around 3000 ft Tuesday morning, staying below the Pass during the day as light snow shower activity continues along the west slopes of the Cascades. Snow shower activity dwindles Tuesday night. A stronger system approaches the region late Wednesday.

Extended Snow Level (ft)

Monday Night* Tuesday Tuesday Night Wednesday
West North 3500' 2500' 2000' 2000'
Snoqualmie Pass 4500' 2500' 2500' 3000'
Mt. Hood 6500' 3000' 2500' 3000'
West North Elevation
Monday Night* 3500'
Tuesday 2500'
Tuesday Night 2000'
Wednesday 2000'
Snoqualmie Pass Elevation
Monday Night* 4500'
Tuesday 2500'
Tuesday Night 2500'
Wednesday 3000'
Mt. Hood Elevation
Monday Night* 6500'
Tuesday 3000'
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 Nov 19, 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’.

Updated Mountain Weather Zone Name Changes – December 2020