Issued: 6:48 AM PST Wednesday, December 20, 2023
by Dallas Glass

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

Weather Synopsis

We're in for a couple of dry and mild days in the mountains. A passing storm to our north and a cut-off low off the coast of California will maintain a split jet stream around the region.

This morning, you may find low clouds and patch fog in the mountain valleys and passes. These conditions could persist particularly near and just east of the Cascade crest. Light easterly flow through the Passes should continue to draw clouds into the mountain gaps. As it eases in the afternoon, you might see a brief reprieve from clouds. Elsewhere, you'll likely find plenty of sunshine and temperatures in the mid-30s to low 40s. 

Things don't change much overnight and into Thursday. The only noticeable difference will be increasing high clouds. You'll see these first in the Olympics and North Cascades Wednesday night, but they should gradually spread further south during the day. The increase in clouds and a slight uptick in westerly winds herald the approach of a storm that arrives Friday. 

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 Dry and mild. Bands of high clouds in the afternoon.
Wednesday Night Mostly cloudy and mild.
Wednesday Low clouds and fog in the morning. Bands of high clouds in the afternoon.
Wednesday Night Mostly cloudy and mild. SSW winds becoming light to moderate.
Wednesday Low clouds and fog in the morning, becoming mostly sunny in the afternoon.
Wednesday Night Increasing high clouds, becoming partly to mostly cloudy.
Wednesday Low clouds and fog in the mountain valleys and pass this morning. Becoming mostly sunny.
Wednesday Night Bands of high clouds and mild.
Wednesday Low clouds and fog near and east of the Pass. Mostly sunny above. Light E flow decreasing slightly in the afternoon.
Wednesday Night Partly cloudy with low clouds and fog likely at Pass level. Light E flow.
Wednesday Low clouds and fog near and east of the Pass. Mostly sunny above. Light E flow decreasing slightly in the afternoon.
Wednesday Night Partly to mostly cloudy with low clouds and fog likely at Pass level. Light E flow.
Wednesday Low clouds in the valleys. Partly to mostly sunny above with increasing high clouds in the afternoon. WSW winds becoming light to moderate.
Wednesday Night Mostly cloudy. Light to moderate WSW winds.
Wednesday Low clouds in the valleys. Partly to mostly sunny above. Winds becoming W light to moderate.
Wednesday Night Low clouds in the valleys with increasing high clouds. Light to moderate W winds increasing.
Wednesday Low clouds in the valleys. Mostly sunny above.
Wednesday Night Low clouds in the valleys with increasing high clouds.
Wednesday Low clouds and fog. Mostly sunny above.
Wednesday Night Low clouds and fog. Passing bands of high clouds.

Precipitation (in)

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

Snow Level (ft)

Wednesday Morning* Wednesday Afternoon* Wednesday Evening* Wednesday Night* Thursday Morning* Thursday Afternoon*
Olympics 7000' 7000' 7000' 7000' 7000' 7000'
West North 6500' 6500' 6000' 6000' 6500' 6500'
West Central 6500' 7000' 6500' 6000' 6500' 7000'
West South 6500' 8000' 7000' 6500' 6500' 7500'
Stevens Pass 5500' 7000' 6500' 5000' 5500' 7500'
Snoqualmie Pass 6000' 7500' 7000' 6500' 6500' 7500'
East North 2500' 4500' 4000' 3000' 3500' 5500'
East Central 5000' 7500' 6500' 5000' 6500' 7500'
East South 5000' 8500' 7000' 6000' 6500' 8000'
Mt. Hood 7500' 8500' 8500' 8500' 8500' 9000'
Olympics Elevation
Wednesday Morning* 7000'
Wednesday Afternoon* 7000'
Wednesday Evening* 7000'
Wednesday Night* 7000'
Thursday Morning* 7000'
Thursday Afternoon* 7000'
West North Elevation
Wednesday Morning* 6500'
Wednesday Afternoon* 6500'
Wednesday Evening* 6000'
Wednesday Night* 6000'
Thursday Morning* 6500'
Thursday Afternoon* 6500'
West Central Elevation
Wednesday Morning* 6500'
Wednesday Afternoon* 7000'
Wednesday Evening* 6500'
Wednesday Night* 6000'
Thursday Morning* 6500'
Thursday Afternoon* 7000'
West South Elevation
Wednesday Morning* 6500'
Wednesday Afternoon* 8000'
Wednesday Evening* 7000'
Wednesday Night* 6500'
Thursday Morning* 6500'
Thursday Afternoon* 7500'
Stevens Pass Elevation
Wednesday Morning* 5500'
Wednesday Afternoon* 7000'
Wednesday Evening* 6500'
Wednesday Night* 5000'
Thursday Morning* 5500'
Thursday Afternoon* 7500'
Snoqualmie Pass Elevation
Wednesday Morning* 6000'
Wednesday Afternoon* 7500'
Wednesday Evening* 7000'
Wednesday Night* 6500'
Thursday Morning* 6500'
Thursday Afternoon* 7500'
East North Elevation
Wednesday Morning* 2500'
Wednesday Afternoon* 4500'
Wednesday Evening* 4000'
Wednesday Night* 3000'
Thursday Morning* 3500'
Thursday Afternoon* 5500'
East Central Elevation
Wednesday Morning* 5000'
Wednesday Afternoon* 7500'
Wednesday Evening* 6500'
Wednesday Night* 5000'
Thursday Morning* 6500'
Thursday Afternoon* 7500'
East South Elevation
Wednesday Morning* 5000'
Wednesday Afternoon* 8500'
Wednesday Evening* 7000'
Wednesday Night* 6000'
Thursday Morning* 6500'
Thursday Afternoon* 8000'
Mt. Hood Elevation
Wednesday Morning* 7500'
Wednesday Afternoon* 8500'
Wednesday Evening* 8500'
Wednesday Night* 8500'
Thursday Morning* 8500'
Thursday Afternoon* 9000'

5000' Temperatures (°F)

Wednesday Wednesday Night
Max / Min Max / Min
Olympics 41 / 35 39 / 35
West North 41 / 35 40 / 36
West Central 44 / 36 42 / 35
West South 43 / 33 37 / 32
Stevens Pass 38 / 30 36 / 30
Snoqualmie Pass 40 / 32 37 / 30
East North 30 / 25 30 / 24
East Central 40 / 34 39 / 33
East South 41 / 34 36 / 32
Mt. Hood 41 / 34 39 / 36
Olympics 5000' Temperature Forecast
(Max / Min)
Wednesday 41 / 35
Wednesday Night 39 / 35
West North 5000' Temperature Forecast
(Max / Min)
Wednesday 41 / 35
Wednesday Night 40 / 36
West Central 5000' Temperature Forecast
(Max / Min)
Wednesday 44 / 36
Wednesday Night 42 / 35
West South 5000' Temperature Forecast
(Max / Min)
Wednesday 43 / 33
Wednesday Night 37 / 32
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Wednesday 38 / 30
Wednesday Night 36 / 30
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Wednesday 40 / 32
Wednesday Night 37 / 30
East North 5000' Temperature Forecast
(Max / Min)
Wednesday 30 / 25
Wednesday Night 30 / 24
East Central 5000' Temperature Forecast
(Max / Min)
Wednesday 40 / 34
Wednesday Night 39 / 33
East South 5000' Temperature Forecast
(Max / Min)
Wednesday 41 / 34
Wednesday Night 36 / 32
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Wednesday 41 / 34
Wednesday Night 39 / 36

Ridgeline Winds (mph)

Wednesday Morning Wednesday Afternoon Wednesday Evening Wednesday Night
Olympics SW 5-15 WSW 5-15 SW 5-15 SW 5-15
West North SSW 5-15 SSW 5-15 SW 5-15 SSW 10-20
West Central SW 0-10 SW 5-15 SW 5-15 SW 5-15
West South SW 0-10 WSW 5-15 WSW 5-15 WSW 5-15
Stevens Pass W 0-10 W 0-10 W 5-15 W 5-15
Snoqualmie Pass WSW 0-10 W 5-15 W 5-15 W 5-15
East North WSW 5-15 WSW 10-20 WSW 10-20 WSW 10-20
East Central WSW 5-15 W 10-20 W 10-20 W 15-25
East South SW 0-10 WSW 5-15 W 5-15 W 5-15
Mt. Hood S 0-10 SW 5-15 SW 5-15 SW 5-15
Olympics Ridgeline Winds (mph)
Wednesday Morning SW 5-15
Wednesday Afternoon WSW 5-15
Wednesday Evening SW 5-15
Wednesday Night SW 5-15
West North Ridgeline Winds (mph)
Wednesday Morning SSW 5-15
Wednesday Afternoon SSW 5-15
Wednesday Evening SW 5-15
Wednesday Night SSW 10-20
West Central Ridgeline Winds (mph)
Wednesday Morning SW 0-10
Wednesday Afternoon SW 5-15
Wednesday Evening SW 5-15
Wednesday Night SW 5-15
West South Ridgeline Winds (mph)
Wednesday Morning SW 0-10
Wednesday Afternoon WSW 5-15
Wednesday Evening WSW 5-15
Wednesday Night WSW 5-15
Stevens Pass Ridgeline Winds (mph)
Wednesday Morning W 0-10
Wednesday Afternoon W 0-10
Wednesday Evening W 5-15
Wednesday Night W 5-15
Snoqualmie Pass Ridgeline Winds (mph)
Wednesday Morning WSW 0-10
Wednesday Afternoon W 5-15
Wednesday Evening W 5-15
Wednesday Night W 5-15
East North Ridgeline Winds (mph)
Wednesday Morning WSW 5-15
Wednesday Afternoon WSW 10-20
Wednesday Evening WSW 10-20
Wednesday Night WSW 10-20
East Central Ridgeline Winds (mph)
Wednesday Morning WSW 5-15
Wednesday Afternoon W 10-20
Wednesday Evening W 10-20
Wednesday Night W 15-25
East South Ridgeline Winds (mph)
Wednesday Morning SW 0-10
Wednesday Afternoon WSW 5-15
Wednesday Evening W 5-15
Wednesday Night W 5-15
Mt. Hood Ridgeline Winds (mph)
Wednesday Morning S 0-10
Wednesday Afternoon SW 5-15
Wednesday Evening SW 5-15
Wednesday Night SW 5-15

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

Previous forecast from Dec 19, 2023

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’.