Issued: 2:01 PM PDT Sunday, March 21, 2021
by Dennis D'Amico

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

Weather Synopsis

A warm front will spread increasing precipitation over the area this evening as W or SW ridgeline winds increase as well.  The front will pass through the central Cascades a few hours after midnight as it shifts the heavier precipitation down near Mt Hood.  A Puget Sound convergence zone will start in the Mt Loop to Hwy 2 corridor behind the front and shift to the I-90 corridor in the morning hours enhancing snowfall rates locally.  The trailing longwave trough associated with the frontal system will pass east of the Cascades tomorrow, keeping us in a cool and showery pattern. If you see a few sunbreaks in the morning on the west side of the Cascade crest, don't be fooled, clouds should fill back in.  Showers will become more scattered in the afternoon, except in the Mt Hood area and from Crystal Mt down to Mt Rainier where the dregs of the convergence zone will linger longest and the low-level flow becomes more W-NW.  Strong ridgeline westerly winds will decrease from north to south tomorrow. The best chance for extended sunbreaks tomorrow will be over in the Olympics and further east of the Cascade crest. 

Showers will taper off Monday night as we dry out.  Broad scale ridging offshore will lead to mostly dry conditions on Tuesday. A frontal system upstream will try to undercut the ridge and will likely lead to a cloudy day with the chance of very light rain or snow near the Canadian border and more sunshine south of Washington State. 

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
Sunday Night Light to moderate rain and snow becoming showers after midnight. Strong ridgeline winds.
Monday Partly to mostly cloudy with scattered light rain and snow showers.
Sunday Night Moderate to occasionally heavy rain and snow becoming light to moderate showers after midnight. Strong ridgeline winds.
Monday Mostly cloudy with scattered light rain and snow showers.
Sunday Night Moderate to occasionally heavy rain and snow becoming light to moderate showers late tonight. Strong ridgeline winds.
Monday Cloudy with light to occasionally moderate rain and snow showers becoming scattered light showers in the afternoon. Ridgeline winds decreasing in the afternoon.
Sunday Night Light to moderate rain and snow increasing in the evening and becoming occasionally heavy Paradise area. Heaviest precipitation Paradise area. Strong ridgeline winds.
Monday Cloudy with light to occasionally moderate rain and snow showers. Strong ridgeline winds decreasing in the afternoon.
Sunday Night Light to moderate rain and snow becoming light to moderate showers late tonight. Strong ridgeline winds. Moderate west winds at Pass level increasing late.
Monday Cloudy with light to occasionally moderate rain and snow showers becoming scattered light showers in the afternoon. Strong ridgeline and Pass level winds in the morning, decreasing in the afternoon.
Sunday Night Moderate to occasionally heavy rain and snow becoming moderate showers late tonight. Strong ridgeline winds. Moderate west winds at Pass level increasing late.
Monday Cloudy with light to occasionally moderate rain and snow showers. Strong ridgeline and Pass level winds in the morning, decreasing in the afternoon.
Sunday Night Light to moderate rain and snow becoming light to occasionally moderate showers late tonight. Strong ridgeline winds.
Monday Mostly cloudy with scattered rain and snow showers becoming isolated showers in the afternoon. Strong ridgeline winds decreasing in the afternoon.
Sunday Night Light to moderate rain and snow becoming light to occasionally moderate showers late tonight. Strong ridgeline winds.
Monday Mostly cloudy with scattered rain and snow showers becoming isolated showers in the afternoon. Strong ridgeline winds decreasing in the afternoon.
Sunday Night Light to occasionally moderate rain and snow developing in the evening. Strong ridgeline winds.
Monday Mostly cloudy with scattered rain and snow showers becoming isolated showers in the afternoon. Strong ridgeline winds decreasing in the afternoon.
Sunday Night Moderate to occasionally heavy rain and snow developing in the evening. Strong ridgeline winds.
Monday Cloudy with light to moderate rain and snow showers. Strong ridgeline winds.

Issued: 2:01 PM PDT Sunday, March 21, 2021

Precipitation (in)

Sunday Night Monday Monday Night Tuesday
5 pm - 5 am 5 am - 5 pm 5 pm - 5 am 5 am - 5 pm
Hurricane Ridge 0.50 LT 0.25 0 0
Mt Baker Ski Area 0.75 -1.00 0.25 0 0
Mt. Loop - Barlow Pass 1.00 0.25 0 0
Stevens Pass 0.50 - 0.75 LT 0.25 0 0
Snoqualmie Pass 0.75 -1.00 0.25 - 0.50 0 0
Crystal Mt 0.25 - 0.50 0.25 - 0.50 LT 0.10 0
Paradise 1.00 - 1.50 0.25 - 0.50 LT 0.10 0
White Pass 0.50 - 0.75 LT 0.25 LT 0.10 0
Washington Pass 0.25 - 0.50 LT 0.10 0 0
Mission Ridge LT 0.25 LT 0.10 0 0
Salmon la Sac - Gallagher Head 0.50 LT 0.25 0 0
Tieton River - Darland Mt. 0.25 - 0.50 LT 0.10 LT 0.10 0
Mt Hood Meadows 0.75 0.50 LT 0.10 0
Timberline 1.00 0.50 - 0.75 LT 0.25 0
Hurricane Ridge Precipitation (in)
Sunday Night 0.50
Monday LT 0.25
Monday Night 0
Tuesday 0
Mt Baker Ski Area Precipitation (in)
Sunday Night 0.75 -1.00
Monday 0.25
Monday Night 0
Tuesday 0
Mt. Loop - Barlow Pass Precipitation (in)
Sunday Night 1.00
Monday 0.25
Monday Night 0
Tuesday 0
Stevens Pass Precipitation (in)
Sunday Night 0.50 - 0.75
Monday LT 0.25
Monday Night 0
Tuesday 0
Snoqualmie Pass Precipitation (in)
Sunday Night 0.75 -1.00
Monday 0.25 - 0.50
Monday Night 0
Tuesday 0
Crystal Mt Precipitation (in)
Sunday Night 0.25 - 0.50
Monday 0.25 - 0.50
Monday Night LT 0.10
Tuesday 0
Paradise Precipitation (in)
Sunday Night 1.00 - 1.50
Monday 0.25 - 0.50
Monday Night LT 0.10
Tuesday 0
White Pass Precipitation (in)
Sunday Night 0.50 - 0.75
Monday LT 0.25
Monday Night LT 0.10
Tuesday 0
Washington Pass Precipitation (in)
Sunday Night 0.25 - 0.50
Monday LT 0.10
Monday Night 0
Tuesday 0
Mission Ridge Precipitation (in)
Sunday Night LT 0.25
Monday LT 0.10
Monday Night 0
Tuesday 0
Salmon la Sac - Gallagher Head Precipitation (in)
Sunday Night 0.50
Monday LT 0.25
Monday Night 0
Tuesday 0
Tieton River - Darland Mt. Precipitation (in)
Sunday Night 0.25 - 0.50
Monday LT 0.10
Monday Night LT 0.10
Tuesday 0
Mt Hood Meadows Precipitation (in)
Sunday Night 0.75
Monday 0.50
Monday Night LT 0.10
Tuesday 0
Timberline Precipitation (in)
Sunday Night 1.00
Monday 0.50 - 0.75
Monday Night LT 0.25
Tuesday 0

Issued: 2:01 PM PDT Sunday, March 21, 2021

Snow Level (ft)

Sunday Evening Sunday Night Monday Morning Monday Afternoon Monday Evening Monday Night Tuesday Morning Tuesday Afternoon
Olympics 4000' 3000' 2500' 3500' 2500' 2000' 2500' 3500'
West North 3000' 3000' 2500' 3000' 2500' 1000' 2500' 3500'
West Central 3000' 3000' 2500' 3000' 2500' 1500' 2500' 3500'
West South 3000' 3500' 2500' 3500' 2500' 1500' 2500' 3500'
Stevens Pass 2500' 3000' 2500' 3000' 2500' 1500' 2500' 3500'
Snoqualmie Pass 2500' 3000' 2500' 3000' 2500' 1500' 2500' 3500'
East North 3000' 3000' 3000' 4000' 2500' 1000' 2500' 4000'
East Central 3500' 3500' 3000' 4000' 2500' 1500' 3000' 4500'
East South 3500' 3500' 3000' 4000' 2500' 1500' 3000' 4500'
Mt. Hood 3500' 4000' 3000' 3500' 2500' 2000' 3000' 4000'
Olympics Elevation
Sunday Evening 4000'
Sunday Night 3000'
Monday Morning 2500'
Monday Afternoon 3500'
Monday Evening 2500'
Monday Night 2000'
Tuesday Morning 2500'
Tuesday Afternoon 3500'
West North Elevation
Sunday Evening 3000'
Sunday Night 3000'
Monday Morning 2500'
Monday Afternoon 3000'
Monday Evening 2500'
Monday Night 1000'
Tuesday Morning 2500'
Tuesday Afternoon 3500'
West Central Elevation
Sunday Evening 3000'
Sunday Night 3000'
Monday Morning 2500'
Monday Afternoon 3000'
Monday Evening 2500'
Monday Night 1500'
Tuesday Morning 2500'
Tuesday Afternoon 3500'
West South Elevation
Sunday Evening 3000'
Sunday Night 3500'
Monday Morning 2500'
Monday Afternoon 3500'
Monday Evening 2500'
Monday Night 1500'
Tuesday Morning 2500'
Tuesday Afternoon 3500'
Stevens Pass Elevation
Sunday Evening 2500'
Sunday Night 3000'
Monday Morning 2500'
Monday Afternoon 3000'
Monday Evening 2500'
Monday Night 1500'
Tuesday Morning 2500'
Tuesday Afternoon 3500'
Snoqualmie Pass Elevation
Sunday Evening 2500'
Sunday Night 3000'
Monday Morning 2500'
Monday Afternoon 3000'
Monday Evening 2500'
Monday Night 1500'
Tuesday Morning 2500'
Tuesday Afternoon 3500'
East North Elevation
Sunday Evening 3000'
Sunday Night 3000'
Monday Morning 3000'
Monday Afternoon 4000'
Monday Evening 2500'
Monday Night 1000'
Tuesday Morning 2500'
Tuesday Afternoon 4000'
East Central Elevation
Sunday Evening 3500'
Sunday Night 3500'
Monday Morning 3000'
Monday Afternoon 4000'
Monday Evening 2500'
Monday Night 1500'
Tuesday Morning 3000'
Tuesday Afternoon 4500'
East South Elevation
Sunday Evening 3500'
Sunday Night 3500'
Monday Morning 3000'
Monday Afternoon 4000'
Monday Evening 2500'
Monday Night 1500'
Tuesday Morning 3000'
Tuesday Afternoon 4500'
Mt. Hood Elevation
Sunday Evening 3500'
Sunday Night 4000'
Monday Morning 3000'
Monday Afternoon 3500'
Monday Evening 2500'
Monday Night 2000'
Tuesday Morning 3000'
Tuesday Afternoon 4000'

Issued: 2:01 PM PDT Sunday, March 21, 2021

5000' Temperatures (°F)

Sunday Night Monday
Max / Min Max / Min
Olympics 28 / 20 31 / 21
West North 26 / 21 28 / 20
West Central 26 / 22 29 / 20
West South 27 / 26 30 / 23
Stevens Pass 26 / 25 29 / 21
Snoqualmie Pass 27 / 25 29 / 21
East North 27 / 21 29 / 21
East Central 27 / 24 30 / 22
East South 28 / 24 31 / 24
Mt. Hood 28 / 26 29 / 26
Olympics 5000' Temperature Forecast
(Max / Min)
Sunday Night 28 / 20
Monday 31 / 21
West North 5000' Temperature Forecast
(Max / Min)
Sunday Night 26 / 21
Monday 28 / 20
West Central 5000' Temperature Forecast
(Max / Min)
Sunday Night 26 / 22
Monday 29 / 20
West South 5000' Temperature Forecast
(Max / Min)
Sunday Night 27 / 26
Monday 30 / 23
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Sunday Night 26 / 25
Monday 29 / 21
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Sunday Night 27 / 25
Monday 29 / 21
East North 5000' Temperature Forecast
(Max / Min)
Sunday Night 27 / 21
Monday 29 / 21
East Central 5000' Temperature Forecast
(Max / Min)
Sunday Night 27 / 24
Monday 30 / 22
East South 5000' Temperature Forecast
(Max / Min)
Sunday Night 28 / 24
Monday 31 / 24
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Sunday Night 28 / 26
Monday 29 / 26

Issued: 2:01 PM PDT Sunday, March 21, 2021

Ridgeline Winds (mph)

Sunday Evening Sunday Night Monday Morning Monday Afternoon
Olympics SW 20-30 WSW 20-30 W 10-20 WNW 10-20
West North SSW 25-35 SW 20-30 W 10-20 W 5-15
West Central SW 20-30 WSW 20-30 W 15-25 WNW 10-20
West South WSW 20-30 WSW 30-40 W 15-25 WNW 10-20
Stevens Pass WSW 20-30 WSW 25-35 W 15-25 WNW 10-20
Snoqualmie Pass WSW 20-30 WSW 30-40 W 20-30 WNW 15-25
East North WSW 20-30 WSW 25-35 W 20-30 WNW 10-20
East Central WSW 20-30 W 25-35 W 30-40 WNW 20-30
East South WSW 15-25 WSW 25-35 W 25-35 WNW 15-25
Mt. Hood WSW 25-35 WSW 35-50 W 30-40 WNW 20-30
Olympics Ridgeline Winds (mph)
Sunday Evening SW 20-30
Sunday Night WSW 20-30
Monday Morning W 10-20
Monday Afternoon WNW 10-20
West North Ridgeline Winds (mph)
Sunday Evening SSW 25-35
Sunday Night SW 20-30
Monday Morning W 10-20
Monday Afternoon W 5-15
West Central Ridgeline Winds (mph)
Sunday Evening SW 20-30
Sunday Night WSW 20-30
Monday Morning W 15-25
Monday Afternoon WNW 10-20
West South Ridgeline Winds (mph)
Sunday Evening WSW 20-30
Sunday Night WSW 30-40
Monday Morning W 15-25
Monday Afternoon WNW 10-20
Stevens Pass Ridgeline Winds (mph)
Sunday Evening WSW 20-30
Sunday Night WSW 25-35
Monday Morning W 15-25
Monday Afternoon WNW 10-20
Snoqualmie Pass Ridgeline Winds (mph)
Sunday Evening WSW 20-30
Sunday Night WSW 30-40
Monday Morning W 20-30
Monday Afternoon WNW 15-25
East North Ridgeline Winds (mph)
Sunday Evening WSW 20-30
Sunday Night WSW 25-35
Monday Morning W 20-30
Monday Afternoon WNW 10-20
East Central Ridgeline Winds (mph)
Sunday Evening WSW 20-30
Sunday Night W 25-35
Monday Morning W 30-40
Monday Afternoon WNW 20-30
East South Ridgeline Winds (mph)
Sunday Evening WSW 15-25
Sunday Night WSW 25-35
Monday Morning W 25-35
Monday Afternoon WNW 15-25
Mt. Hood Ridgeline Winds (mph)
Sunday Evening WSW 25-35
Sunday Night WSW 35-50
Monday Morning W 30-40
Monday Afternoon WNW 20-30

Issued: 2:01 PM PDT Sunday, March 21, 2021

Extended Weather Synopsis

A fast moving system in NW flow will temporarily buckle the ridge on Wednesday, bringing a quick shot of rain and snow to the region. The ridge will begin to rebuild offshore on Thursday with lingering showers and clouds mainly along the west slopes of the Cascades. 

Extended Snow Level (ft)

Tuesday Night Wednesday Wednesday Night Thursday
West North 2500' 3500' 2500' 4000'
Snoqualmie Pass 2500' 3500' 3000' 4000'
Mt. Hood 3500' 4000' 3000' 4500'
West North Elevation
Tuesday Night 2500'
Wednesday 3500'
Wednesday Night 2500'
Thursday 4000'
Snoqualmie Pass Elevation
Tuesday Night 2500'
Wednesday 3500'
Wednesday Night 3000'
Thursday 4000'
Mt. Hood Elevation
Tuesday Night 3500'
Wednesday 4000'
Wednesday Night 3000'
Thursday 4500'

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

Previous forecast from Mar 21, 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’.