Issued: 7:00 AM PST Tuesday, December 22, 2020
by Dennis D'Amico

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

Weather Synopsis

Snow showers along the west slopes of the Cascades in NW flow aloft will wind down quickly this morning as strong upper level ridging builds offshore. Snow levels have dropped considerably since yesterday along the west slopes of the Cascades but temperatures are still in the process of cooling along the east slopes of the Cascades this morning. Low clouds associated with the shower activity will linger longest along the west slopes of the Cascades, especially from about I-90 and south to Mt Hood.  Mt Hood may pick up a quick 1-3 additional inches of snow this morning. The Olympics, east slopes of the Cascades and northwest Cascades will see more sunshine than other areas today.  

A mostly clear night is expected tonight as the upper level ridge shifts closer to our area. On Wednesday, mostly sunny skies are expected along with warming temperatures west of the Cascade crest. Offshore flow with easterly winds will start to kick up in the Cascade Passes, creating temperature inversions and milder temperatures along the mid and upper slopes in many locations. 

 

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
Tuesday Mostly sunny.
Tuesday Night Mostly clear.
Tuesday Partly cloudy in the morning becoming mostly sunny.
Tuesday Night Mostly clear.
Tuesday Mostly cloudy in the morning with scattered light snow showers becoming partly sunny in the afternoon.
Tuesday Night Mostly clear.
Tuesday Mostly cloudy in the morning with scattered light snow showers becoming partly sunny in the afternoon. More clouds Paradise area, more sunbreaks White Pass and Crystal.
Tuesday Night Mostly clear.
Tuesday Mostly cloudy in the morning with scattered light snow showers becoming partly sunny in the afternoon. Strong west winds at Pass level in the morning easing to moderate in the afternoon.
Tuesday Night Mostly clear. Variable winds at Pass level becoming light east winds overnight.
Tuesday Mostly cloudy in the morning with scattered light snow showers becoming partly sunny in the afternoon. Strong west winds at Pass level in the morning easing to moderate in the afternoon.
Tuesday Night Mostly clear. Variable winds at Pass level becoming light east winds overnight.
Tuesday Partly cloudy in the morning becoming mostly sunny.
Tuesday Night Mostly clear.
Tuesday Mostly cloudy in the morning with isolated light snow showers near the Cascade crest becoming mostly sunny in the afternoon.
Tuesday Night Mostly clear.
Tuesday Mostly cloudy in the morning with isolated light snow showers near the Cascade crest becoming mostly sunny in the afternoon.
Tuesday Night Mostly clear.
Tuesday Cloudy in the morning with light snow showers becoming partly to mostly cloudy in the afternoon. Sunbreaks more likely east-side of the mountain.
Tuesday Night Mostly clear.

Precipitation (in)

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

Snow Level (ft)

Tuesday Morning Tuesday Afternoon Tuesday Evening Tuesday Night Wednesday Morning Wednesday Afternoon*
Olympics 1500' 1500' 2000' 2000' 5000' 8000'
West North 1000' 1000' 1000' 1000' 3000' 6000'
West Central 1500' 1500' 1000' 1000' 3500' 6500'
West South 1500' 1500' 1000' 1000' 4500' 8000'
Stevens Pass 1500' 1500' 1000' 1000' 2000' 5000'
Snoqualmie Pass 1500' 1500' 1000' 1000' 2500' 6000'
East North 2500' 1500' 1000' 0 2000' 3500'
East Central 2500' 2000' 1000' 1000' 2000' 3500'
East South 2500' 2000' 1000' 1000' 3000' 4500'
Mt. Hood 2000' 2000' 2000' 1000' 4000' 8500'
Olympics Elevation
Tuesday Morning 1500'
Tuesday Afternoon 1500'
Tuesday Evening 2000'
Tuesday Night 2000'
Wednesday Morning 5000'
Wednesday Afternoon* 8000'
West North Elevation
Tuesday Morning 1000'
Tuesday Afternoon 1000'
Tuesday Evening 1000'
Tuesday Night 1000'
Wednesday Morning 3000'
Wednesday Afternoon* 6000'
West Central Elevation
Tuesday Morning 1500'
Tuesday Afternoon 1500'
Tuesday Evening 1000'
Tuesday Night 1000'
Wednesday Morning 3500'
Wednesday Afternoon* 6500'
West South Elevation
Tuesday Morning 1500'
Tuesday Afternoon 1500'
Tuesday Evening 1000'
Tuesday Night 1000'
Wednesday Morning 4500'
Wednesday Afternoon* 8000'
Stevens Pass Elevation
Tuesday Morning 1500'
Tuesday Afternoon 1500'
Tuesday Evening 1000'
Tuesday Night 1000'
Wednesday Morning 2000'
Wednesday Afternoon* 5000'
Snoqualmie Pass Elevation
Tuesday Morning 1500'
Tuesday Afternoon 1500'
Tuesday Evening 1000'
Tuesday Night 1000'
Wednesday Morning 2500'
Wednesday Afternoon* 6000'
East North Elevation
Tuesday Morning 2500'
Tuesday Afternoon 1500'
Tuesday Evening 1000'
Tuesday Night 0'
Wednesday Morning 2000'
Wednesday Afternoon* 3500'
East Central Elevation
Tuesday Morning 2500'
Tuesday Afternoon 2000'
Tuesday Evening 1000'
Tuesday Night 1000'
Wednesday Morning 2000'
Wednesday Afternoon* 3500'
East South Elevation
Tuesday Morning 2500'
Tuesday Afternoon 2000'
Tuesday Evening 1000'
Tuesday Night 1000'
Wednesday Morning 3000'
Wednesday Afternoon* 4500'
Mt. Hood Elevation
Tuesday Morning 2000'
Tuesday Afternoon 2000'
Tuesday Evening 2000'
Tuesday Night 1000'
Wednesday Morning 4000'
Wednesday Afternoon* 8500'

5000' Temperatures (°F)

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

Ridgeline Winds (mph)

Tuesday Morning Tuesday Afternoon Tuesday Evening Tuesday Night
Olympics NW 5-15 NW 5-15 NNW 0-10 NW 0-10
West North NW 5-15 WNW 5-15 WNW 0-10 W 0-10
West Central WNW 15-25 WNW 10-20 WNW 0-10 WNW 0-10
West South WNW 20-30 WNW 10-20 NW 0-10 W 0-10
Stevens Pass WNW 20-30 WNW 10-20 WNW 5-15 NW 0-10
Snoqualmie Pass WNW 25-35 NW 10-20 NW 5-15 NW 0-10
East North NW 25-35 NW 15-25 WNW 10-20 W 5-15
East Central WNW 25-35 NW 10-20 NW 5-15 W 0-10
East South WNW 20-30 WNW 10-20 NW 5-15 W 0-10
Mt. Hood WNW 30-40 W 20-30 NW 10-20 VAR 0-10
Olympics Ridgeline Winds (mph)
Tuesday Morning NW 5-15
Tuesday Afternoon NW 5-15
Tuesday Evening NNW 0-10
Tuesday Night NW 0-10
West North Ridgeline Winds (mph)
Tuesday Morning NW 5-15
Tuesday Afternoon WNW 5-15
Tuesday Evening WNW 0-10
Tuesday Night W 0-10
West Central Ridgeline Winds (mph)
Tuesday Morning WNW 15-25
Tuesday Afternoon WNW 10-20
Tuesday Evening WNW 0-10
Tuesday Night WNW 0-10
West South Ridgeline Winds (mph)
Tuesday Morning WNW 20-30
Tuesday Afternoon WNW 10-20
Tuesday Evening NW 0-10
Tuesday Night W 0-10
Stevens Pass Ridgeline Winds (mph)
Tuesday Morning WNW 20-30
Tuesday Afternoon WNW 10-20
Tuesday Evening WNW 5-15
Tuesday Night NW 0-10
Snoqualmie Pass Ridgeline Winds (mph)
Tuesday Morning WNW 25-35
Tuesday Afternoon NW 10-20
Tuesday Evening NW 5-15
Tuesday Night NW 0-10
East North Ridgeline Winds (mph)
Tuesday Morning NW 25-35
Tuesday Afternoon NW 15-25
Tuesday Evening WNW 10-20
Tuesday Night W 5-15
East Central Ridgeline Winds (mph)
Tuesday Morning WNW 25-35
Tuesday Afternoon NW 10-20
Tuesday Evening NW 5-15
Tuesday Night W 0-10
East South Ridgeline Winds (mph)
Tuesday Morning WNW 20-30
Tuesday Afternoon WNW 10-20
Tuesday Evening NW 5-15
Tuesday Night W 0-10
Mt. Hood Ridgeline Winds (mph)
Tuesday Morning WNW 30-40
Tuesday Afternoon W 20-30
Tuesday Evening NW 10-20
Tuesday Night VAR 0-10

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

Previous forecast from Dec 21, 2020

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’.