Issued: 7:06 AM PST Wednesday, December 15, 2021
by Robert Hahn

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

Weather Synopsis

Cold temperatures remain in place throughout the forecast period.

A closed low dropping SE toward the Oregon coast lifts a band of mostly light snowfall NE, impacting the southern Cascades and Olympics on Wednesday. Increasing light to moderate easterly low-level flow should peak during the afternoon bringing chilly winds through the mountain gaps. Combining the low-level flow with SE winds aloft should help squeeze out moisture along the east slopes of the Cascades from around highway 2 southward.

The upper low moves onshore Wednesday night. Light snowfall should decrease from north to south across the region. Easterly low-level flow decreases into the light range. Temperatures should be cold, particularly in areas that see some clearing skies (most likely in the North Cascades).

Most areas could see 1-4" with this storm, with slightly heavier amounts possible in the southern and eastern Olympics and Mt. Hood areas.

A weak shortwave trough moves in from the NW on Thursday, bringing an increase in light snow showers and very weak convergence focusing on the west slopes of the central Cascades. An additional 1-3" of snow could fall with this feature.

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 Increasing periods of light snow. Strong ridgeline wind gusts.
Wednesday Night Snow flurries or very light snow during the evening hours, then partial clearing overnight.
Wednesday Periods of very light snow. Cold.
Wednesday Night Mostly cloudy in the evening with light snow possible overnight. Cold.
Wednesday Cloudy. Cold.
Wednesday Night Mostly cloudy in the evening with light snow possible overnight. Cold.
Wednesday Light snow developing.
Wednesday Night Cloudy. Cold.
Wednesday Light snow is possible during the afternoon. Light E winds become moderate in the afternoon at the Pass.
Wednesday Night Light snow is possible at times. Moderate E winds become light at the Pass.
Wednesday Light snow developing from late morning onwards. Light E winds become moderate in the afternoon at the Pass.
Wednesday Night Light snow at times. Moderate E winds become light at the Pass.
Wednesday Cloudy with snow flurries possible.
Wednesday Night Mostly cloudy.
Wednesday Cloudy with light snow developing from late morning onwards.
Wednesday Night Light snow tapering during the evening, then becoming cloudy with flurries.
Wednesday Cloudy early with light snow developing around mid-morning slightly during the afternoon.
Wednesday Night Light snow tapering during the evening, then becoming cloudy with flurries.
Wednesday Moderate snow develops in the morning and increases during the afternoon
Wednesday Night Light to occasionally moderate snow.

Precipitation (in)

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

Snow Level (ft)

Wednesday Morning* Wednesday Afternoon* Wednesday Evening* Wednesday Night* Thursday Morning Thursday Afternoon
Olympics 500' 2000' 1500' 2000' 500' 2000'
West North 500' 1500' 1500' 0 0 1000'
West Central 1500' 1500' 1000' 500' 0 1500'
West South 500' 500' 500' 0 0 2000'
Stevens Pass 500' 500' 0 500' 0 1500'
Snoqualmie Pass 500' 500' 0 500' 0 1500'
East North 0 500' 0 0 0 1000'
East Central 500' 500' 0 500' 0 1500'
East South 500' 1000' 500' 500' 0 2000'
Mt. Hood 500' 1500' 1500' 1000' 0 2500'
Olympics Elevation
Wednesday Morning* 500'
Wednesday Afternoon* 2000'
Wednesday Evening* 1500'
Wednesday Night* 2000'
Thursday Morning 500'
Thursday Afternoon 2000'
West North Elevation
Wednesday Morning* 500'
Wednesday Afternoon* 1500'
Wednesday Evening* 1500'
Wednesday Night* 0'
Thursday Morning 0'
Thursday Afternoon 1000'
West Central Elevation
Wednesday Morning* 1500'
Wednesday Afternoon* 1500'
Wednesday Evening* 1000'
Wednesday Night* 500'
Thursday Morning 0'
Thursday Afternoon 1500'
West South Elevation
Wednesday Morning* 500'
Wednesday Afternoon* 500'
Wednesday Evening* 500'
Wednesday Night* 0'
Thursday Morning 0'
Thursday Afternoon 2000'
Stevens Pass Elevation
Wednesday Morning* 500'
Wednesday Afternoon* 500'
Wednesday Evening* 0'
Wednesday Night* 500'
Thursday Morning 0'
Thursday Afternoon 1500'
Snoqualmie Pass Elevation
Wednesday Morning* 500'
Wednesday Afternoon* 500'
Wednesday Evening* 0'
Wednesday Night* 500'
Thursday Morning 0'
Thursday Afternoon 1500'
East North Elevation
Wednesday Morning* 0'
Wednesday Afternoon* 500'
Wednesday Evening* 0'
Wednesday Night* 0'
Thursday Morning 0'
Thursday Afternoon 1000'
East Central Elevation
Wednesday Morning* 500'
Wednesday Afternoon* 500'
Wednesday Evening* 0'
Wednesday Night* 500'
Thursday Morning 0'
Thursday Afternoon 1500'
East South Elevation
Wednesday Morning* 500'
Wednesday Afternoon* 1000'
Wednesday Evening* 500'
Wednesday Night* 500'
Thursday Morning 0'
Thursday Afternoon 2000'
Mt. Hood Elevation
Wednesday Morning* 500'
Wednesday Afternoon* 1500'
Wednesday Evening* 1500'
Wednesday Night* 1000'
Thursday Morning 0'
Thursday Afternoon 2500'

5000' Temperatures (°F)

Wednesday Wednesday Night
Max / Min Max / Min
Olympics 24 / 21 22 / 18
West North 25 / 21 19 / 16
West Central 22 / 20 19 / 15
West South 22 / 18 19 / 17
Stevens Pass 20 / 18 16 / 12
Snoqualmie Pass 20 / 18 20 / 14
East North 17 / 13 14 / 11
East Central 19 / 15 16 / 12
East South 21 / 17 17 / 14
Mt. Hood 23 / 20 23 / 21
Olympics 5000' Temperature Forecast
(Max / Min)
Wednesday 24 / 21
Wednesday Night 22 / 18
West North 5000' Temperature Forecast
(Max / Min)
Wednesday 25 / 21
Wednesday Night 19 / 16
West Central 5000' Temperature Forecast
(Max / Min)
Wednesday 22 / 20
Wednesday Night 19 / 15
West South 5000' Temperature Forecast
(Max / Min)
Wednesday 22 / 18
Wednesday Night 19 / 17
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Wednesday 20 / 18
Wednesday Night 16 / 12
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Wednesday 20 / 18
Wednesday Night 20 / 14
East North 5000' Temperature Forecast
(Max / Min)
Wednesday 17 / 13
Wednesday Night 14 / 11
East Central 5000' Temperature Forecast
(Max / Min)
Wednesday 19 / 15
Wednesday Night 16 / 12
East South 5000' Temperature Forecast
(Max / Min)
Wednesday 21 / 17
Wednesday Night 17 / 14
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Wednesday 23 / 20
Wednesday Night 23 / 21

Ridgeline Winds (mph)

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

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

Previous forecast from Dec 14, 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’.