Issued: 7:00 AM PST Thursday, December 31, 2020
by Dennis D'Amico

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

Weather Synopsis

A surface low on the backside of an upper-level trough tracked across the Strait of Juan de Fuca overnight and is dissipating as it crosses east of the Cascades today. The low tracked a bit further north than forecast overnight with the result being more snow for the northwest Cascades including the Mt Baker area overnight. Showers have largely cut-off for the north Cascades this morning and will stay focused on the Mtn Loop Hwy and south to the Mt Hood area through the early afternoon. Westerly ridgeline winds will be strong from about I-90 and south today. Expect a fair amount of spillover with the showers east of the Crest for these same areas. The Cascade Passes saw their winds shift to West early this morning and milder Pacific air is mixing in. Snow levels across the area will be in the 4000-4500' range today. 

Even as showers taper off this afternoon and evening, we will see very little break in the action as a warm front begins to lift north across the area late tonight and tomorrow. Expect a few hours of light to locally moderate precipitation late tonight and Friday morning with the south and the central Cascades seeing a potential "dry" window late morning-mid-day Friday.  The associated cold front should reach the Washington Coast by Friday afternoon. Temperatures and snow levels will be on the rise Friday as warm air is advected into the region. 

Note: 5000' Temperatures delayed this morning  

 

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
Thursday Mostly cloudy with a chance of showers in the morning, overcast in the afternoon.
Thursday Night Light to moderate rain and snow developing overnight.
Thursday Mostly cloudy with a chance of showers in the morning, overcast in the afternoon.
Thursday Night Light to moderate rain and snow developing overnight.
Thursday Light to moderate rain and snow showers in the morning, showers becoming scattered in the afternoon.
Thursday Night Cloudy with periods of light rain and snow.
Thursday Light to moderate rain and snow showers in the morning, showers becoming scattered in the afternoon. Showers heaviest Paradise and White Pass areas in the morning.
Thursday Night Cloudy with periods of light rain and snow, occasionally moderate Paradise area.
Thursday Moderate rain and snow showers in the morning, showers becoming scattered in the afternoon. Moderate west winds at Pass level.
Thursday Night Cloudy with periods of light rain and snow.
Thursday Moderate to occasionally heavy rain and snow showers in the morning, showers becoming scattered in the afternoon. Moderate west winds at Pass level.
Thursday Night Cloudy with periods of light rain and snow.
Thursday Mostly cloudy with a chance of showers in the morning, overcast in the afternoon.
Thursday Night Cloudy with periods of light rain and snow.
Thursday Light to occasionally moderate rain and snow showers in the morning, showers becoming isolated in the afternoon.
Thursday Night Cloudy with periods of light rain and snow.
Thursday Light to occasionally moderate rain and snow showers in the morning, showers becoming isolated in the afternoon.
Thursday Night Cloudy with periods of light rain and snow.
Thursday Moderate rain and snow showers in the morning, showers becoming scattered in the afternoon. Very windy.
Thursday Night Cloudy with periods of light rain and snow.

Precipitation (in)

Thursday Thursday Night Friday
4 am - 4 pm 4 pm - 4 am 4 am - 4 pm
Hurricane Ridge LT 0.10 0.25 - 0.50 0.50
Mt Baker Ski Area LT 0.10 0.50 0.75 -1.00
Mt. Loop - Barlow Pass 0.50 0.25 - 0.50 0.50
Stevens Pass 0.50 LT 0.25 0.25
Snoqualmie Pass 0.75 -1.00 LT 0.25 0.25
Crystal Mt LT 0.25 0.25 LT 0.25
Paradise 0.75 0.50 0.25 - 0.50
White Pass 0.50 - 0.75 LT 0.25 LT 0.10
Washington Pass LT 0.10 LT 0.25 0.25
Mission Ridge LT 0.10 LT 0.10 LT 0.10
Salmon la Sac - Gallagher Head 0.50 LT 0.25 LT 0.25
Tieton River - Darland Mt. 0.25 LT 0.10 LT 0.10
Mt Hood Meadows 0.75 LT 0.25 LT 0.10
Timberline 0.75 LT 0.25 LT 0.10
Hurricane Ridge Precipitation (in)
Thursday LT 0.10
Thursday Night 0.25 - 0.50
Friday 0.50
Mt Baker Ski Area Precipitation (in)
Thursday LT 0.10
Thursday Night 0.50
Friday 0.75 -1.00
Mt. Loop - Barlow Pass Precipitation (in)
Thursday 0.50
Thursday Night 0.25 - 0.50
Friday 0.50
Stevens Pass Precipitation (in)
Thursday 0.50
Thursday Night LT 0.25
Friday 0.25
Snoqualmie Pass Precipitation (in)
Thursday 0.75 -1.00
Thursday Night LT 0.25
Friday 0.25
Crystal Mt Precipitation (in)
Thursday LT 0.25
Thursday Night 0.25
Friday LT 0.25
Paradise Precipitation (in)
Thursday 0.75
Thursday Night 0.50
Friday 0.25 - 0.50
White Pass Precipitation (in)
Thursday 0.50 - 0.75
Thursday Night LT 0.25
Friday LT 0.10
Washington Pass Precipitation (in)
Thursday LT 0.10
Thursday Night LT 0.25
Friday 0.25
Mission Ridge Precipitation (in)
Thursday LT 0.10
Thursday Night LT 0.10
Friday LT 0.10
Salmon la Sac - Gallagher Head Precipitation (in)
Thursday 0.50
Thursday Night LT 0.25
Friday LT 0.25
Tieton River - Darland Mt. Precipitation (in)
Thursday 0.25
Thursday Night LT 0.10
Friday LT 0.10
Mt Hood Meadows Precipitation (in)
Thursday 0.75
Thursday Night LT 0.25
Friday LT 0.10
Timberline Precipitation (in)
Thursday 0.75
Thursday Night LT 0.25
Friday LT 0.10

Snow Level (ft)

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

5000' Temperatures (°F)

Thursday Thursday Night
Max / Min Max / Min
Olympics / /
West North / /
West Central / /
West South / /
Stevens Pass / /
Snoqualmie Pass / /
East North / /
East Central / /
East South / /
Mt. Hood / /
Olympics 5000' Temperature Forecast
(Max / Min)
Thursday /
Thursday Night /
West North 5000' Temperature Forecast
(Max / Min)
Thursday /
Thursday Night /
West Central 5000' Temperature Forecast
(Max / Min)
Thursday /
Thursday Night /
West South 5000' Temperature Forecast
(Max / Min)
Thursday /
Thursday Night /
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Thursday /
Thursday Night /
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Thursday /
Thursday Night /
East North 5000' Temperature Forecast
(Max / Min)
Thursday /
Thursday Night /
East Central 5000' Temperature Forecast
(Max / Min)
Thursday /
Thursday Night /
East South 5000' Temperature Forecast
(Max / Min)
Thursday /
Thursday Night /
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Thursday /
Thursday Night /

Ridgeline Winds (mph)

Thursday Morning Thursday Afternoon Thursday Evening Thursday Night
Olympics W 5-15 SW 0-10 S 10-20 SSW 20-30
West North SW 0-10 SW 0-10 S 10-20 S 10-20
West Central W 15-25 W 10-20 S 5-15 S 10-20
West South WSW 20-30 W 10-20 SW 5-15 SW 15-25
Stevens Pass WSW 15-25 W 5-15 W 5-15 SSE 5-15
Snoqualmie Pass WSW 20-30 W 15-25 W 10-20 SSE 10-20
East North W 10-20 W 5-15 WSW 5-15 WSW 10-20
East Central WSW 20-30 W 15-25 WSW 5-15 SSE 5-15
East South WSW 20-30 W 15-25 WSW 5-15 SSE 5-15
Mt. Hood W 30-40 W 20-30 W 10-20 SW 5-15
Olympics Ridgeline Winds (mph)
Thursday Morning W 5-15
Thursday Afternoon SW 0-10
Thursday Evening S 10-20
Thursday Night SSW 20-30
West North Ridgeline Winds (mph)
Thursday Morning SW 0-10
Thursday Afternoon SW 0-10
Thursday Evening S 10-20
Thursday Night S 10-20
West Central Ridgeline Winds (mph)
Thursday Morning W 15-25
Thursday Afternoon W 10-20
Thursday Evening S 5-15
Thursday Night S 10-20
West South Ridgeline Winds (mph)
Thursday Morning WSW 20-30
Thursday Afternoon W 10-20
Thursday Evening SW 5-15
Thursday Night SW 15-25
Stevens Pass Ridgeline Winds (mph)
Thursday Morning WSW 15-25
Thursday Afternoon W 5-15
Thursday Evening W 5-15
Thursday Night SSE 5-15
Snoqualmie Pass Ridgeline Winds (mph)
Thursday Morning WSW 20-30
Thursday Afternoon W 15-25
Thursday Evening W 10-20
Thursday Night SSE 10-20
East North Ridgeline Winds (mph)
Thursday Morning W 10-20
Thursday Afternoon W 5-15
Thursday Evening WSW 5-15
Thursday Night WSW 10-20
East Central Ridgeline Winds (mph)
Thursday Morning WSW 20-30
Thursday Afternoon W 15-25
Thursday Evening WSW 5-15
Thursday Night SSE 5-15
East South Ridgeline Winds (mph)
Thursday Morning WSW 20-30
Thursday Afternoon W 15-25
Thursday Evening WSW 5-15
Thursday Night SSE 5-15
Mt. Hood Ridgeline Winds (mph)
Thursday Morning W 30-40
Thursday Afternoon W 20-30
Thursday Evening W 10-20
Thursday Night SW 5-15

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

Previous forecast from Dec 30, 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’.