Issued: 2:04 PM PDT Wednesday, March 17, 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 cold closed low churning in the PNW offshore waters continues to nudge the ridge of high pressure further east, but not before one more mostly clear night. Expect a shallow or minimal refreeze Wednesday night as freezing levels remain elevated. Ridgeline winds throughout the region continue to increase in the light to moderate range out of the S and SE.

The cold front reaches the coastline Thursday morning and then the Cascades late in the day. Ahead of the front, bands of light rain and snow arrive first in the Olympics and then throughout the Cascades by the afternoon hours. We anticipate 1-3" of snow to fall above around 5000 ft. Snow levels drop late in the day across the Olympic Mountains and late in the day for the Cascades. S winds should peak during the morning in the moderate to occasionally strong range for areas exposed to this flow direction.

Thursday night and Friday, the closed low spins and weakens in the Washington state coastal waters. A perturbation riding northward along the cold front lifts a wave of moderate rain and snow through the Cascades Thursday evening. Precipitation should become mostly light and showery overnight. Light showers continue for the Cascades on Friday with snow levels lowering and accumulating snows likely above 3000 ft. Precipitation associated with the low center moves into the Olympic mountains with moderate precipitation for Hurricane Ridge on Friday; Hurricane Ridge could pick up more than 6" of snow during the day.

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 Night Mostly clear with thin high clouds.
Thursday Periods of light rain and snow, potentially moderate at times during the morning hours.
Wednesday Night Mostly clear with thin high clouds.
Thursday Periods of light rain and snow developing during the morning and increasing during the afternoon hours.
Wednesday Night Mostly clear with thin high clouds.
Thursday Periods of light rain and snow developing during the morning and increasing during the afternoon hours.
Wednesday Night Mostly clear with thin high clouds.
Thursday Periods of light rain and snow developing during the morning and increasing during the afternoon hours.
Wednesday Night Mostly clear with thin high clouds. Increasing light to moderate E winds at the Pass.
Thursday Light rain and snow possible from late morning onwards. Decreasing light to occasionally moderate E winds at the Pass, possibly switching W late in the day.
Wednesday Night Mostly clear with thin high clouds. Increasing light to moderate E winds at the Pass.
Thursday Light rain and snow possible from late morning onwards. Decreasing light to moderate E winds at the Pass, possibly switching W late in the day.
Wednesday Night Mostly clear with thin high clouds.
Thursday Clouds thickening during the morning with light rain and snow at times during the afternoon.
Wednesday Night Mostly clear with thin high clouds.
Thursday Clouds thickening early with light rain and snow at times from mid-morning onwards.
Wednesday Night Mostly clear with thin high clouds.
Thursday Periods of light rain and snow.
Wednesday Night Mostly clear with thin high clouds thickening toward morning.
Thursday Periods of light rain and snow.

Issued: 2:04 PM PDT Wednesday, March 17, 2021

Precipitation (in)

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

Issued: 2:04 PM PDT Wednesday, March 17, 2021

Snow Level (ft)

Wednesday Evening* Wednesday Night* Thursday Morning* Thursday Afternoon* Thursday Evening Thursday Night Friday Morning* Friday Afternoon
Olympics 6000' 6000' 5000' 4000' 3000' 2500' 2500' 2500'
West North 6000' 5000' 4500' 5000' 4500' 3500' 2500' 3000'
West Central 6000' 5500' 5500' 5000' 4500' 3500' 2500' 3500'
West South 6000' 5000' 5000' 5000' 4500' 3000' 2500' 3500'
Stevens Pass 5500' 4000' 4000' 5000' 4500' 3500' 2000' 3500'
Snoqualmie Pass 6000' 5000' 5000' 5000' 4500' 3500' 2500' 3500'
East North 5000' 4000' 3500' 5000' 5000' 4000' 2000' 3500'
East Central 5500' 5000' 5000' 5000' 5000' 4000' 2500' 4000'
East South 5500' 5000' 4500' 5500' 4500' 3500' 2500' 4000'
Mt. Hood 7000' 7500' 6500' 5500' 4500' 3500' 2500' 3500'
Olympics Elevation
Wednesday Evening* 6000'
Wednesday Night* 6000'
Thursday Morning* 5000'
Thursday Afternoon* 4000'
Thursday Evening 3000'
Thursday Night 2500'
Friday Morning* 2500'
Friday Afternoon 2500'
West North Elevation
Wednesday Evening* 6000'
Wednesday Night* 5000'
Thursday Morning* 4500'
Thursday Afternoon* 5000'
Thursday Evening 4500'
Thursday Night 3500'
Friday Morning* 2500'
Friday Afternoon 3000'
West Central Elevation
Wednesday Evening* 6000'
Wednesday Night* 5500'
Thursday Morning* 5500'
Thursday Afternoon* 5000'
Thursday Evening 4500'
Thursday Night 3500'
Friday Morning* 2500'
Friday Afternoon 3500'
West South Elevation
Wednesday Evening* 6000'
Wednesday Night* 5000'
Thursday Morning* 5000'
Thursday Afternoon* 5000'
Thursday Evening 4500'
Thursday Night 3000'
Friday Morning* 2500'
Friday Afternoon 3500'
Stevens Pass Elevation
Wednesday Evening* 5500'
Wednesday Night* 4000'
Thursday Morning* 4000'
Thursday Afternoon* 5000'
Thursday Evening 4500'
Thursday Night 3500'
Friday Morning* 2000'
Friday Afternoon 3500'
Snoqualmie Pass Elevation
Wednesday Evening* 6000'
Wednesday Night* 5000'
Thursday Morning* 5000'
Thursday Afternoon* 5000'
Thursday Evening 4500'
Thursday Night 3500'
Friday Morning* 2500'
Friday Afternoon 3500'
East North Elevation
Wednesday Evening* 5000'
Wednesday Night* 4000'
Thursday Morning* 3500'
Thursday Afternoon* 5000'
Thursday Evening 5000'
Thursday Night 4000'
Friday Morning* 2000'
Friday Afternoon 3500'
East Central Elevation
Wednesday Evening* 5500'
Wednesday Night* 5000'
Thursday Morning* 5000'
Thursday Afternoon* 5000'
Thursday Evening 5000'
Thursday Night 4000'
Friday Morning* 2500'
Friday Afternoon 4000'
East South Elevation
Wednesday Evening* 5500'
Wednesday Night* 5000'
Thursday Morning* 4500'
Thursday Afternoon* 5500'
Thursday Evening 4500'
Thursday Night 3500'
Friday Morning* 2500'
Friday Afternoon 4000'
Mt. Hood Elevation
Wednesday Evening* 7000'
Wednesday Night* 7500'
Thursday Morning* 6500'
Thursday Afternoon* 5500'
Thursday Evening 4500'
Thursday Night 3500'
Friday Morning* 2500'
Friday Afternoon 3500'

Issued: 2:04 PM PDT Wednesday, March 17, 2021

5000' Temperatures (°F)

Wednesday Night Thursday
Max / Min Max / Min
Olympics 35 / 30 33 / 30
West North 37 / 31 36 / 33
West Central 35 / 30 37 / 31
West South 39 / 32 37 / 33
Stevens Pass 35 / 29 41 / 33
Snoqualmie Pass 34 / 29 36 / 31
East North 34 / 27 37 / 27
East Central 34 / 29 38 / 30
East South 36 / 29 39 / 28
Mt. Hood 39 / 33 41 / 32
Olympics 5000' Temperature Forecast
(Max / Min)
Wednesday Night 35 / 30
Thursday 33 / 30
West North 5000' Temperature Forecast
(Max / Min)
Wednesday Night 37 / 31
Thursday 36 / 33
West Central 5000' Temperature Forecast
(Max / Min)
Wednesday Night 35 / 30
Thursday 37 / 31
West South 5000' Temperature Forecast
(Max / Min)
Wednesday Night 39 / 32
Thursday 37 / 33
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Wednesday Night 35 / 29
Thursday 41 / 33
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Wednesday Night 34 / 29
Thursday 36 / 31
East North 5000' Temperature Forecast
(Max / Min)
Wednesday Night 34 / 27
Thursday 37 / 27
East Central 5000' Temperature Forecast
(Max / Min)
Wednesday Night 34 / 29
Thursday 38 / 30
East South 5000' Temperature Forecast
(Max / Min)
Wednesday Night 36 / 29
Thursday 39 / 28
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Wednesday Night 39 / 33
Thursday 41 / 32

Issued: 2:04 PM PDT Wednesday, March 17, 2021

Ridgeline Winds (mph)

Wednesday Evening Wednesday Night Thursday Morning Thursday Afternoon
Olympics S 10-20 SSE 10-20 S 20-30 SSW 20-30
West North SSE 5-15 SSE 10-20 SSE 20-30 S 15-25
West Central ESE 10-20 ESE 10-20 SE 15-25 SSE 10-20
West South SSE 5-15 SE 10-20 S 15-25 S 10-20
Stevens Pass SE 5-15 SE 10-20 SE 10-20 SSE 10-20
Snoqualmie Pass ESE 10-20 ESE 10-20 SE 15-25 SE 10-20
East North SE 5-15 SSE 10-20 SE 10-20 SSE 10-20
East Central SSE 5-15 SSE 10-20 SSE 15-25 SSE 15-25
East South SE 5-15 SE 5-15 S 10-20 S 10-20
Mt. Hood SSE 10-20 S 15-25 SSW 25-35 SSW 15-25
Olympics Ridgeline Winds (mph)
Wednesday Evening S 10-20
Wednesday Night SSE 10-20
Thursday Morning S 20-30
Thursday Afternoon SSW 20-30
West North Ridgeline Winds (mph)
Wednesday Evening SSE 5-15
Wednesday Night SSE 10-20
Thursday Morning SSE 20-30
Thursday Afternoon S 15-25
West Central Ridgeline Winds (mph)
Wednesday Evening ESE 10-20
Wednesday Night ESE 10-20
Thursday Morning SE 15-25
Thursday Afternoon SSE 10-20
West South Ridgeline Winds (mph)
Wednesday Evening SSE 5-15
Wednesday Night SE 10-20
Thursday Morning S 15-25
Thursday Afternoon S 10-20
Stevens Pass Ridgeline Winds (mph)
Wednesday Evening SE 5-15
Wednesday Night SE 10-20
Thursday Morning SE 10-20
Thursday Afternoon SSE 10-20
Snoqualmie Pass Ridgeline Winds (mph)
Wednesday Evening ESE 10-20
Wednesday Night ESE 10-20
Thursday Morning SE 15-25
Thursday Afternoon SE 10-20
East North Ridgeline Winds (mph)
Wednesday Evening SE 5-15
Wednesday Night SSE 10-20
Thursday Morning SE 10-20
Thursday Afternoon SSE 10-20
East Central Ridgeline Winds (mph)
Wednesday Evening SSE 5-15
Wednesday Night SSE 10-20
Thursday Morning SSE 15-25
Thursday Afternoon SSE 15-25
East South Ridgeline Winds (mph)
Wednesday Evening SE 5-15
Wednesday Night SE 5-15
Thursday Morning S 10-20
Thursday Afternoon S 10-20
Mt. Hood Ridgeline Winds (mph)
Wednesday Evening SSE 10-20
Wednesday Night S 15-25
Thursday Morning SSW 25-35
Thursday Afternoon SSW 15-25

Issued: 2:04 PM PDT Wednesday, March 17, 2021

Extended Weather Synopsis

The extended forecast period looks unstable and cool with significant snow accumulations for locations above 2000-3000 ft. A vertically stacked and weakening cold upper low becomes an open trough as it approaches the Washington coastline, arriving by Saturday morning. It continues to produce scattered rain and snow showers as snow levels lower across the region. The trough axis slides east of the Cascades by Saturday afternoon, turning upper-level flow NWerly. Destabilized by cool air aloft, the low-level westerly flow should produce convective showers across the west slopes of the Cascades. Residual moisture and shower activity changes transitions to heavier precipitation by Sunday afternoon as a system dropping into the region on NW flow aims the jetstream directly at the Pacific Northwest. This storm could bring significant snow above 3000 ft Sunday afternoon into Monday.

Extended Snow Level (ft)

Friday Night Saturday Saturday Night Sunday
West North 2500' 2500' 2000' 2000'
Snoqualmie Pass 2500' 3000' 2500' 2000'
Mt. Hood 2500' 3000' 2500' 2500'
West North Elevation
Friday Night 2500'
Saturday 2500'
Saturday Night 2000'
Sunday 2000'
Snoqualmie Pass Elevation
Friday Night 2500'
Saturday 3000'
Saturday Night 2500'
Sunday 2000'
Mt. Hood Elevation
Friday Night 2500'
Saturday 3000'
Saturday Night 2500'
Sunday 2500'

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

Previous forecast from Mar 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’.