Issued: 2:03 PM PST Thursday, November 18, 2021
by Robert Hahn

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

Weather Synopsis

A shortwave upper trough and tightening surface low move into the waters off the Oregon Coast late Thursday. Radar echoes indicate a well-developed shield of moisture spinning moving into western Washington and Oregon Thursday afternoon. Despite the gradual weakening of the low, the increasingly compact system could crank out significant snow totals through mid-day Friday. Precipitation will focus to the north of the low center with a tight band of moderate to heavy rain and snow from the central Washington Cascades southward. Cool air east of the Cascade Crest combined with light E low-level flow should keep precipitation frozen at the passes. The E flow will also enable significant snowfall east of the Cascade Crest. Strong ridgeline winds wrapping around the compact low center will focus on Mt. Hood Thursday night, easing slightly on Friday.

Rain and snow taper and end from north to south on Friday as the shortwave trough slides ashore and flow switches westerly. Westerly flow allows temperatures to moderate along the east slopes of the Cascades. Significant snowfall should be mostly confined to Mt. Hood during the daylight hours Friday. Storm total snowfall should be in the 4-12" from the mountain loop from the Mountain Loop southward, with higher totals possible on the southern volcanoes. Higher snow levels further south in the range may limit lower elevation snowfall for Mt. Hood north to Mt. Rainier.

Friday afternoon, expect low clouds to remain banked against the west slopes of the Cascades with more sunshine east of the Cascade Crest as cool WNW flow spills over a weak offshore ridge. Expect little change in the pattern with generally an inch or less of snow in weak convergence over northern Washington Friday night into Saturday.

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
Thursday Night Moderate rain and snow.
Friday Partly cloudy with isolated snow flurries early in the day.
Thursday Night Light rain and snow, decreasing or ending by morning.
Friday Light snow flurries early, then becoming mostly cloudy.
Thursday Night Moderate rain and snow, heavy at times southern part.
Friday Light snow tapering to snow flurries.
Thursday Night Heavy rain and snow at Paradise; moderate to heavy rain and snow at Crystal and White Pass.
Friday Light to moderate snow early, tapering to flurries.
Thursday Night Decreasing moderate to heavy snow. Light E wind at pass level.
Friday Light snow tapering to flurries early. Light E wind early switching W at the Pass.
Thursday Night Moderate to heavy snow (and rain at lower elevations west of the pass). Light E wind at pass level.
Friday Light snow tapering to flurries. Light E wind early switching W at the Pass.
Thursday Night Decreasing light snow.
Friday Snow flurries early, then becoming partly to mostly cloudy.
Thursday Night Moderate to heavy snow.
Friday Light snow tapering to flurries, then mostly cloudy skies.
Thursday Night Moderate to occasionally heavy rain and snow.
Friday Light rain and snow tapering by afternoon.
Thursday Night Moderate rain and snow. Gradual cooling. Strong ridgeline winds.
Friday Moderate to occasionally heavy rain and snow becoming light or ending in the afternoon. Cooling temperatures. Moderate ridgeline winds with strong gusts.

Precipitation (in)

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

Snow Level (ft)

Thursday Evening* Thursday Night* Friday Morning Friday Afternoon Friday Evening Friday Night Saturday Morning Saturday Afternoon
Olympics 2500' 3000' 3000' 4500' 3500' 2500' 3000' 4000'
West North 3000' 3000' 2500' 3500' 3500' 2000' 2000' 3000'
West Central 3000' 2500' 3000' 3500' 3500' 2000' 2500' 3000'
West South 4000' 4500' 4000' 3500' 3500' 3000' 2500' 4000'
Stevens Pass 2000' 2000' 2000' 3000' 3500' 2500' 3000' 3500'
Snoqualmie Pass 2500' 2500' 2500' 3000' 3000' 3000' 3000' 3500'
East North 1500' 1000' 1000' 4000' 4000' 2500' 2500' 3500'
East Central 2500' 2500' 2500' 3000' 3500' 2500' 2500' 4000'
East South 4000' 4000' 3500' 4000' 4000' 3000' 2500' 4000'
Mt. Hood 6500' 5500' 5500' 3500' 4000' 3500' 3500' 4000'
Olympics Elevation
Thursday Evening* 2500'
Thursday Night* 3000'
Friday Morning 3000'
Friday Afternoon 4500'
Friday Evening 3500'
Friday Night 2500'
Saturday Morning 3000'
Saturday Afternoon 4000'
West North Elevation
Thursday Evening* 3000'
Thursday Night* 3000'
Friday Morning 2500'
Friday Afternoon 3500'
Friday Evening 3500'
Friday Night 2000'
Saturday Morning 2000'
Saturday Afternoon 3000'
West Central Elevation
Thursday Evening* 3000'
Thursday Night* 2500'
Friday Morning 3000'
Friday Afternoon 3500'
Friday Evening 3500'
Friday Night 2000'
Saturday Morning 2500'
Saturday Afternoon 3000'
West South Elevation
Thursday Evening* 4000'
Thursday Night* 4500'
Friday Morning 4000'
Friday Afternoon 3500'
Friday Evening 3500'
Friday Night 3000'
Saturday Morning 2500'
Saturday Afternoon 4000'
Stevens Pass Elevation
Thursday Evening* 2000'
Thursday Night* 2000'
Friday Morning 2000'
Friday Afternoon 3000'
Friday Evening 3500'
Friday Night 2500'
Saturday Morning 3000'
Saturday Afternoon 3500'
Snoqualmie Pass Elevation
Thursday Evening* 2500'
Thursday Night* 2500'
Friday Morning 2500'
Friday Afternoon 3000'
Friday Evening 3000'
Friday Night 3000'
Saturday Morning 3000'
Saturday Afternoon 3500'
East North Elevation
Thursday Evening* 1500'
Thursday Night* 1000'
Friday Morning 1000'
Friday Afternoon 4000'
Friday Evening 4000'
Friday Night 2500'
Saturday Morning 2500'
Saturday Afternoon 3500'
East Central Elevation
Thursday Evening* 2500'
Thursday Night* 2500'
Friday Morning 2500'
Friday Afternoon 3000'
Friday Evening 3500'
Friday Night 2500'
Saturday Morning 2500'
Saturday Afternoon 4000'
East South Elevation
Thursday Evening* 4000'
Thursday Night* 4000'
Friday Morning 3500'
Friday Afternoon 4000'
Friday Evening 4000'
Friday Night 3000'
Saturday Morning 2500'
Saturday Afternoon 4000'
Mt. Hood Elevation
Thursday Evening* 6500'
Thursday Night* 5500'
Friday Morning 5500'
Friday Afternoon 3500'
Friday Evening 4000'
Friday Night 3500'
Saturday Morning 3500'
Saturday Afternoon 4000'

5000' Temperatures (°F)

Thursday Night Friday
Max / Min Max / Min
Olympics 31 / 24 30 / 19
West North 28 / 25 27 / 22
West Central 30 / 28 29 / 22
West South 34 / 31 31 / 24
Stevens Pass 27 / 23 28 / 22
Snoqualmie Pass 30 / 26 28 / 19
East North 23 / 18 30 / 23
East Central 28 / 23 29 / 23
East South 34 / 29 31 / 26
Mt. Hood 37 / 35 37 / 27
Olympics 5000' Temperature Forecast
(Max / Min)
Thursday Night 31 / 24
Friday 30 / 19
West North 5000' Temperature Forecast
(Max / Min)
Thursday Night 28 / 25
Friday 27 / 22
West Central 5000' Temperature Forecast
(Max / Min)
Thursday Night 30 / 28
Friday 29 / 22
West South 5000' Temperature Forecast
(Max / Min)
Thursday Night 34 / 31
Friday 31 / 24
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Thursday Night 27 / 23
Friday 28 / 22
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Thursday Night 30 / 26
Friday 28 / 19
East North 5000' Temperature Forecast
(Max / Min)
Thursday Night 23 / 18
Friday 30 / 23
East Central 5000' Temperature Forecast
(Max / Min)
Thursday Night 28 / 23
Friday 29 / 23
East South 5000' Temperature Forecast
(Max / Min)
Thursday Night 34 / 29
Friday 31 / 26
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Thursday Night 37 / 35
Friday 37 / 27

Ridgeline Winds (mph)

Thursday Evening Thursday Night Friday Morning Friday Afternoon
Olympics SSE 0-10 NNE 0-10 NNW 5-15 WNW 5-15
West North S 5-15 NNW 0-10 NNW 0-10 WSW 0-10
West Central SSE 5-15 S 0-10 WNW 5-15 WNW 10-20
West South SSW 10-20 SW 5-15 NW 5-15 NW 5-15
Stevens Pass SSE 5-15 SSE 0-10 WNW 5-15 WNW 10-20
Snoqualmie Pass ESE 5-15 SE 0-10 WNW 10-20 WNW 15-25
East North SSE 5-15 SW 0-10 NW 10-20 NW 10-20
East Central SSW 10-20 SW 5-15 NW 10-20 NW 15-25
East South SSW 5-15 SSW 10-20 WNW 10-20 NW 10-20
Mt. Hood SW 30-40 SW 30-40 W 25-35 WNW 20-30
Olympics Ridgeline Winds (mph)
Thursday Evening SSE 0-10
Thursday Night NNE 0-10
Friday Morning NNW 5-15
Friday Afternoon WNW 5-15
West North Ridgeline Winds (mph)
Thursday Evening S 5-15
Thursday Night NNW 0-10
Friday Morning NNW 0-10
Friday Afternoon WSW 0-10
West Central Ridgeline Winds (mph)
Thursday Evening SSE 5-15
Thursday Night S 0-10
Friday Morning WNW 5-15
Friday Afternoon WNW 10-20
West South Ridgeline Winds (mph)
Thursday Evening SSW 10-20
Thursday Night SW 5-15
Friday Morning NW 5-15
Friday Afternoon NW 5-15
Stevens Pass Ridgeline Winds (mph)
Thursday Evening SSE 5-15
Thursday Night SSE 0-10
Friday Morning WNW 5-15
Friday Afternoon WNW 10-20
Snoqualmie Pass Ridgeline Winds (mph)
Thursday Evening ESE 5-15
Thursday Night SE 0-10
Friday Morning WNW 10-20
Friday Afternoon WNW 15-25
East North Ridgeline Winds (mph)
Thursday Evening SSE 5-15
Thursday Night SW 0-10
Friday Morning NW 10-20
Friday Afternoon NW 10-20
East Central Ridgeline Winds (mph)
Thursday Evening SSW 10-20
Thursday Night SW 5-15
Friday Morning NW 10-20
Friday Afternoon NW 15-25
East South Ridgeline Winds (mph)
Thursday Evening SSW 5-15
Thursday Night SSW 10-20
Friday Morning WNW 10-20
Friday Afternoon NW 10-20
Mt. Hood Ridgeline Winds (mph)
Thursday Evening SW 30-40
Thursday Night SW 30-40
Friday Morning W 25-35
Friday Afternoon WNW 20-30

Extended Weather Synopsis

A ridge amplifies as it moves onshore Saturday night into Sunday, bringing milder air and rising high freezing levels from south to north across the region. Easterly low-level flow develops gradually and should move significantly colder air pooled at low levels east of the Cascade Crest through the mountain gaps. On Sunday, expect cloudier conditions in the north due to a warm front bringing precipitation to British Columbia. The associated cold front should approach the PNW coastline late Monday with 6,000-11,000 ft freezing levels across the region.

Extended Snow Level (ft)

Saturday Night* Sunday * Sunday Night* Monday
West North 2500' 5000' 7000' 7500'
Snoqualmie Pass 2000' 6000' 7000' 6000'
Mt. Hood 4500' 9000' 1100' 8000'
West North Elevation
Saturday Night* 2500'
Sunday * 5000'
Sunday Night* 7000'
Monday 7500'
Snoqualmie Pass Elevation
Saturday Night* 2000'
Sunday * 6000'
Sunday Night* 7000'
Monday 6000'
Mt. Hood Elevation
Saturday Night* 4500'
Sunday * 9000'
Sunday Night* 1100'
Monday 8000'

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

Previous forecast from Nov 17, 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