Issued: 2:01 PM PST Thursday, December 5, 2024
by Robert Hahn

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

Weather Synopsis

The persistent west coast ridge fends off the storm track through Friday but succumbs to a stronger frontal system approaching Friday night and impacting the area on Saturday. Thursday's fizzled shortwave brought little more than widespread cloud cover to NW Washington, with sunny skies for most other mountain areas. The ridge will briefly rebuild late Thursday night with some cooling associated with the aforementioned shortwave. By Friday, freezing levels rebound back to 9,000-12,000 ft across the region as milder air moves in on increasing SW flow with a chance of isolated showers for the west slopes of the Olympics or Mt Baker areas. During the is time, low clouds/fog will stay locked in for deep valleys, especially along the eastern slopes of the Cascades and near the Cascade Passes. Winds above and below the inversion will be decoupled with generally WSW and light winds above the inversion and E flow below. Snoqualmie Pass remains the only location with moderate E winds at Pass level which are expected to decrease very slightly as time progresses.

The drastic shift in the weather begins Friday night. A low moving toward Heida Gwaii sends a moisture-laden and reasonably sharp frontal boundary toward our region. Most areas will see precipitation start as rain up to around 8000 ft with snow levels dropping following precipitation onset. Steadier precipitation arrives with moderate to locally strong SW winds for the Olympics and Mt Baker areas in the late evening and spreads into the central Washington Cascades overnight, becoming moderate to heavy for the west slopes and Cascade passes. Rain and snow peak Saturday morning with snow levels still near or above the Cascade Crest.  Sharper cooling during the mid-day hours returns snow to middle elevations with significant accumulations expected.

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 Night Partly cloudy. Mild. Ridgeline winds increase into the moderate range late in the day.
Friday High clouds lower and thicken. A chance of isolated rain showers late in the day. Mild.
Thursday Night Partly cloudy. Inversions and low cloud in some lowland valleys. Mild. Ridgeline winds increase into the moderate range late in the day.
Friday High clouds lower and thicken. A chance of isolated rain showers in the afternoon. Mild.
Thursday Night Partly cloudy. Inversions and low cloud in some lowland valleys. Mild.
Friday Filtered sunshine with high clouds lowering late in the day. Mild.
Thursday Night Partly cloudy. Inversions and low cloud in some lowland valleys.
Friday Filtered sunshine with high clouds lowering late in the day. Mild.
Thursday Night Partly cloudy. Persistent inversion with some low cloud at times through the mountain gap. Light ridgeline and E wind through the Pass.
Friday Filtered sunshine with high clouds lowering late in the day. Strong inversion. Light ridgeline and E wind through the Pass.
Thursday Night Partly cloudy. Persistent inversion and low cloud at times through the mountain gap. Mild at mid-elevations; cold at the Pass. Light ridgeline winds decoupled from moderate E wind through the Pass.
Friday Filtered sunshine with high clouds lowering late in the day. Strong inversion. Light ridgeline and moderate E wind through the Pass.
Thursday Night Mostly clear with low cloud. Strong inversion. Ridgeline winds increase into the moderate range late in the day.
Friday Filtered sunshine. Strong inversion. Valley fog.
Thursday Night Mostly clear with low cloud. Strong inversion.
Friday Filtered sunshine. Strong inversion. Valley fog.
Thursday Night Mostly clear with low cloud. Strong inversion.
Friday Filtered sunshine. Strong inversion. Valley fog.
Thursday Night Mostly clear with low cloud. Strong inversion.
Friday Filtered sunshine. Ridgeline winds increase into the moderate range late in the day.

Precipitation (in)

Thursday Night Friday Friday Night Saturday
4 pm - 4 am 4 am - 4 pm 4 pm - 4 am 4 am - 4 pm
Hurricane Ridge 0 0 0.50 - 0.75 0.25
Mt Baker Ski Area 0 0 0.75 1.50
Mt. Loop - Barlow Pass 0 0 0.50 - 0.75 1.50 - 2.00
Stevens Pass 0 0 LT 0.25 1.50
Snoqualmie Pass 0 0 0.25 1.00 - 1.50
Crystal Mt 0 0 0 0.25 - 0.50
Paradise 0 0 LT 0.25 1.00 - 1.50
White Pass 0 0 LT 0.10 0.75
Washington Pass 0 0 0.25 0.50 - 0.75
Mission Ridge 0 0 0 LT 0.25
Salmon la Sac - Gallagher Head 0 0 LT 0.10 0.50
Tieton River - Darland Mt. 0 0 LT 0.10 0.25 - 0.50
Mt Hood Meadows 0 0 0 0.50
Timberline 0 0 0 0.50 - 0.75
Hurricane Ridge Precipitation (in)
Thursday Night 0
Friday 0
Friday Night 0.50 - 0.75
Saturday 0.25
Mt Baker Ski Area Precipitation (in)
Thursday Night 0
Friday 0
Friday Night 0.75
Saturday 1.50
Mt. Loop - Barlow Pass Precipitation (in)
Thursday Night 0
Friday 0
Friday Night 0.50 - 0.75
Saturday 1.50 - 2.00
Stevens Pass Precipitation (in)
Thursday Night 0
Friday 0
Friday Night LT 0.25
Saturday 1.50
Snoqualmie Pass Precipitation (in)
Thursday Night 0
Friday 0
Friday Night 0.25
Saturday 1.00 - 1.50
Crystal Mt Precipitation (in)
Thursday Night 0
Friday 0
Friday Night 0
Saturday 0.25 - 0.50
Paradise Precipitation (in)
Thursday Night 0
Friday 0
Friday Night LT 0.25
Saturday 1.00 - 1.50
White Pass Precipitation (in)
Thursday Night 0
Friday 0
Friday Night LT 0.10
Saturday 0.75
Washington Pass Precipitation (in)
Thursday Night 0
Friday 0
Friday Night 0.25
Saturday 0.50 - 0.75
Mission Ridge Precipitation (in)
Thursday Night 0
Friday 0
Friday Night 0
Saturday LT 0.25
Salmon la Sac - Gallagher Head Precipitation (in)
Thursday Night 0
Friday 0
Friday Night LT 0.10
Saturday 0.50
Tieton River - Darland Mt. Precipitation (in)
Thursday Night 0
Friday 0
Friday Night LT 0.10
Saturday 0.25 - 0.50
Mt Hood Meadows Precipitation (in)
Thursday Night 0
Friday 0
Friday Night 0
Saturday 0.50
Timberline Precipitation (in)
Thursday Night 0
Friday 0
Friday Night 0
Saturday 0.50 - 0.75

Snow Level (ft)

Thursday Evening* Thursday Night* Friday Morning* Friday Afternoon* Friday Evening* Friday Night* Saturday Morning* Saturday Afternoon
Olympics 7500' 10000' 10500' 11000' 9500' 9500' 6500' 4500'
West North 7500' 7500' 9500' 9000' 8500' 8500' 6500' 4500'
West Central 8000' 7500' 10500' 10500' 8500' 9000' 7500' 5000'
West South 8500' 7500' 11500' 11500' 11000' 9500' 8500' 5500'
Stevens Pass 7500' 7000' 10500' 10500' 10000' 9000' 8000' 5000'
Snoqualmie Pass 7500' 7000' 11000' 10500' 10000' 9000' 8000' 5000'
East North 7500' 7000' 10000' 10500' 9500' 8000' 7000' 5000'
East Central 8000' 8000' 10500' 11000' 11000' 9000' 8500' 5500'
East South 8000' 9500' 11000' 11500' 12000' 9000' 8500' 6000'
Mt. Hood 8000' 11000' 11500' 12000' 12000' 11000' 9000' 7000'
Olympics Elevation
Thursday Evening* 7500'
Thursday Night* 10000'
Friday Morning* 10500'
Friday Afternoon* 11000'
Friday Evening* 9500'
Friday Night* 9500'
Saturday Morning* 6500'
Saturday Afternoon 4500'
West North Elevation
Thursday Evening* 7500'
Thursday Night* 7500'
Friday Morning* 9500'
Friday Afternoon* 9000'
Friday Evening* 8500'
Friday Night* 8500'
Saturday Morning* 6500'
Saturday Afternoon 4500'
West Central Elevation
Thursday Evening* 8000'
Thursday Night* 7500'
Friday Morning* 10500'
Friday Afternoon* 10500'
Friday Evening* 8500'
Friday Night* 9000'
Saturday Morning* 7500'
Saturday Afternoon 5000'
West South Elevation
Thursday Evening* 8500'
Thursday Night* 7500'
Friday Morning* 11500'
Friday Afternoon* 11500'
Friday Evening* 11000'
Friday Night* 9500'
Saturday Morning* 8500'
Saturday Afternoon 5500'
Stevens Pass Elevation
Thursday Evening* 7500'
Thursday Night* 7000'
Friday Morning* 10500'
Friday Afternoon* 10500'
Friday Evening* 10000'
Friday Night* 9000'
Saturday Morning* 8000'
Saturday Afternoon 5000'
Snoqualmie Pass Elevation
Thursday Evening* 7500'
Thursday Night* 7000'
Friday Morning* 11000'
Friday Afternoon* 10500'
Friday Evening* 10000'
Friday Night* 9000'
Saturday Morning* 8000'
Saturday Afternoon 5000'
East North Elevation
Thursday Evening* 7500'
Thursday Night* 7000'
Friday Morning* 10000'
Friday Afternoon* 10500'
Friday Evening* 9500'
Friday Night* 8000'
Saturday Morning* 7000'
Saturday Afternoon 5000'
East Central Elevation
Thursday Evening* 8000'
Thursday Night* 8000'
Friday Morning* 10500'
Friday Afternoon* 11000'
Friday Evening* 11000'
Friday Night* 9000'
Saturday Morning* 8500'
Saturday Afternoon 5500'
East South Elevation
Thursday Evening* 8000'
Thursday Night* 9500'
Friday Morning* 11000'
Friday Afternoon* 11500'
Friday Evening* 12000'
Friday Night* 9000'
Saturday Morning* 8500'
Saturday Afternoon 6000'
Mt. Hood Elevation
Thursday Evening* 8000'
Thursday Night* 11000'
Friday Morning* 11500'
Friday Afternoon* 12000'
Friday Evening* 12000'
Friday Night* 11000'
Saturday Morning* 9000'
Saturday Afternoon 7000'

5000' Temperatures (°F)

Thursday Night Friday
Max / Min Max / Min
Olympics 39 / 33 42 / 39
West North 34 / 31 41 / 32
West Central 34 / 30 42 / 31
West South 34 / 31 47 / 34
Stevens Pass 33 / 30 44 / 31
Snoqualmie Pass 33 / 32 42 / 32
East North 32 / 29 39 / 30
East Central 34 / 32 44 / 32
East South 35 / 32 47 / 33
Mt. Hood 37 / 34 51 / 36
Olympics 5000' Temperature Forecast
(Max / Min)
Thursday Night 39 / 33
Friday 42 / 39
West North 5000' Temperature Forecast
(Max / Min)
Thursday Night 34 / 31
Friday 41 / 32
West Central 5000' Temperature Forecast
(Max / Min)
Thursday Night 34 / 30
Friday 42 / 31
West South 5000' Temperature Forecast
(Max / Min)
Thursday Night 34 / 31
Friday 47 / 34
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Thursday Night 33 / 30
Friday 44 / 31
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Thursday Night 33 / 32
Friday 42 / 32
East North 5000' Temperature Forecast
(Max / Min)
Thursday Night 32 / 29
Friday 39 / 30
East Central 5000' Temperature Forecast
(Max / Min)
Thursday Night 34 / 32
Friday 44 / 32
East South 5000' Temperature Forecast
(Max / Min)
Thursday Night 35 / 32
Friday 47 / 33
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Thursday Night 37 / 34
Friday 51 / 36

Ridgeline Winds (mph)

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

Extended Weather Synopsis

After a week of reprieve, we're back to winter in the Pacific Northwest! A secondary frontal system catches up to the first Saturday night, bringing a reinforcing shot of rain and snow as snow levels descend into the 2500-4000 ft range. Around this time, some areas could experience some freezing rain if a melting layer exists above the entrenched cold pool. More westerly flow early Sunday should favor productive snowfall for the west slopes of the Cascades and Passes with snow levels right around 3000 ft. Rain and snow taper as the upper low moves overhead late Sunday. A ridge builds offshore Sunday night and brings us a sunny day on Monday with seasonable temperatures.

 

Extended Snow Level (ft)

Saturday Night Sunday Sunday Night Monday
West North 3000' 2500' 2500' 2500'
Snoqualmie Pass 3000' 3000' 2500' 3000'
Mt. Hood 4000' 3500' 3000' 3500'
West North Elevation
Saturday Night 3000'
Sunday 2500'
Sunday Night 2500'
Monday 2500'
Snoqualmie Pass Elevation
Saturday Night 3000'
Sunday 3000'
Sunday Night 2500'
Monday 3000'
Mt. Hood Elevation
Saturday Night 4000'
Sunday 3500'
Sunday Night 3000'
Monday 3500'

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

Previous forecast from Dec 5, 2024

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’.