Issued: 2:14 PM PST Wednesday, December 25, 2024
by Robert Hahn

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

Weather Synopsis

With this Christmas and Boxing Day day storm Santa delivers a serious punch. This storm is likely to go down as one of the most significant of the year in terms of snow accumulations and contends as a significant mountain wind event.

The system has plenty of moisture to work with as revealed by a bload plume of moisture extending 750 miles to the WSW. As of Christmas afternoon, moderate to heavy snow is spreading throughout the region ahead of a warm front advancing into the area.

The warm front will bring modest warming Wednesday night along with the heaviest sustained precipitation. Expect 1-3" per hour sustained snowfall rates for the west slopes of the Cascades above the 2500-3500 rain/snow line. East flow enables plenty of spillover E of the Cascade Crest where 0.5-2" per hour snowfall rates are expected. Moderate to strong winds will generally peak in the overnight hours as the storm's first wave moves over the region, with the strongest winds likely around Mt. Hood.

On Boxing Day, models continue to indicate the passage of a secondary low across the Straight of Juan Da Fuca into the N Cascades from the morning into the afternoon hours. This will bring very intense W winds wrapping around the south side of the low as a bent-back occlusion ("poisonous tail"). Models are indicating sustained winds of 30-50 mph for areas favored by W winds, so you might expect to find some areas gusting above Hurricane force. The winds will be accompanied by decreasing moderate to heavy snow tapering to showers by the afternoon. Embedded convergence should focus on the southern mountain loop area in the wake of the low center.

Expect snow levels to rise to around 4000 ft west of the Cascade Crest by 4 AM Thursday, but Snoqualmie Pass could remain snow until 10 AM at which point low-level flow should switch W and snow levels rise to around 3500 ft.

Expect mostly light rain and snow showers to linger Thursday evening as steadier rain and snow move into the southern Cascades through the overnight hours associated with the next system. This system won't be as intense, but will still deliver moderate to locally heavy snowfall. Precipitation spreads northward as the package lifts NE during the day Friday. It remains unclear how much moisture will reach as far north as the Canadian border.

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 Heavy rain and snow (moderate for Hurricane Ridge). Moderate to occasionally strong ridgeline winds.
Thursday Moderate rain and snow become light and showery in the afternoon. Moderate to strong ridgeline winds with extreme gusts.
Wednesday Night Heavy rain and snow with the heaviest rates overnight. Moderate to strong ridgeline winds.
Thursday Heavy rain and snow decrease in the afternoon. Mododerate ridgeline winds becoming strong with extreme gusts.
Wednesday Night Heavy rain and snow. Moderate ridgeline winds.
Thursday Heavy rain and snow decrease in the afternoon, but remain locally heavy in convergence. Mododerate ridgeline winds becoming strong with extreme gusts.
Wednesday Night Heavy rain and snow. Increasing moderate ridgeline winds.
Thursday Heavy rain and snow decrease in the afternoon. Strong ridgeline winds with extreme gusts.
Wednesday Night Heavy snow. Increasing moderate ridgeline and light to moderate E wind at the Pass.
Thursday Heavy snow mixing with rain below 4000 ft. Moderate ridgeline winds become strong in the mid-day hours. Light to moderate E winds switch W at the Pass.
Wednesday Night Heavy snow possibly mixing with or changing to rain below 3500 ft overnight. Increasing moderate ridgeline and E wind at the Pass.
Thursday Heavy snow mixing with rain below 4000 ft. Moderate ridgeline winds become strong in the mid-day hours. Light to moderate E winds switch W at the Pass.
Wednesday Night Increasing moderate to heavy snow. Moderate ridgeline winds.
Thursday Moderate to heavy eases in the afternoon. Moderate ridgeline winds become strong with extreme gusts in the mid-day hours.
Wednesday Night Moderate to heavy snow, possibly mixing with rain below 3500 ft overnight. Moderate ridgeline winds.
Thursday Moderate rain and snow become light to moderate and showery in the afternoon. Moderate ridgeline winds become strong to extreme in the mid-day and afternoon hours.
Wednesday Night Moderate to heavy snow, possibly mixing with rain below 3500 ft overnight. Moderate ridgeline winds.
Thursday Moderate rain and snow become light to moderate and showery in the afternoon. Moderate ridgeline winds become strong to extreme in the mid-day and afternoon hours
Wednesday Night Heavy rain and snow. Very strong ridgeline winds.
Thursday Decreasing moderate to heavy rain and snow. Strong to extreme ridgeline winds gradually decrease.

Precipitation (in)

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

Snow Level (ft)

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

5000' Temperatures (°F)

Wednesday Night Thursday
Max / Min Max / Min
Olympics 32 / 30 32 / 27
West North 29 / 28 30 / 27
West Central 27 / 25 30 / 27
West South 31 / 29 31 / 27
Stevens Pass 26 / 23 30 / 27
Snoqualmie Pass 27 / 25 30 / 27
East North 23 / 20 29 / 23
East Central 27 / 24 30 / 27
East South 29 / 26 31 / 28
Mt. Hood 34 / 31 32 / 28
Olympics 5000' Temperature Forecast
(Max / Min)
Wednesday Night 32 / 30
Thursday 32 / 27
West North 5000' Temperature Forecast
(Max / Min)
Wednesday Night 29 / 28
Thursday 30 / 27
West Central 5000' Temperature Forecast
(Max / Min)
Wednesday Night 27 / 25
Thursday 30 / 27
West South 5000' Temperature Forecast
(Max / Min)
Wednesday Night 31 / 29
Thursday 31 / 27
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Wednesday Night 26 / 23
Thursday 30 / 27
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Wednesday Night 27 / 25
Thursday 30 / 27
East North 5000' Temperature Forecast
(Max / Min)
Wednesday Night 23 / 20
Thursday 29 / 23
East Central 5000' Temperature Forecast
(Max / Min)
Wednesday Night 27 / 24
Thursday 30 / 27
East South 5000' Temperature Forecast
(Max / Min)
Wednesday Night 29 / 26
Thursday 31 / 28
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Wednesday Night 34 / 31
Thursday 32 / 28

Ridgeline Winds (mph)

Wednesday Evening Wednesday Night Thursday Morning Thursday Afternoon
Olympics SSW 20-30 SSW 25-35 SW 15-25 WSW 25-35
West North S 15-25 SSE 20-30 S 25-35 WSW 15-25
West Central SE 10-20 SE 15-25 SSW 20-30 WSW 25-35
West South SSW 20-30 SSW 20-30 WSW 30-40 W 30-40
Stevens Pass SSE 5-15 SE 15-25 SE 15-25 W 25-35
Snoqualmie Pass ESE 10-20 SE 20-30 SSW 15-25 W 30-40
East North SSE 5-15 SE 15-25 S 10-20 WSW 30-40
East Central SSW 15-25 SSE 15-25 SW 20-30 W 35-50
East South SSW 10-20 S 15-25 WSW 25-35 W 35-50
Mt. Hood SW 25-35 SW 35-50 WSW 35-50 WSW 30-40
Olympics Ridgeline Winds (mph)
Wednesday Evening SSW 20-30
Wednesday Night SSW 25-35
Thursday Morning SW 15-25
Thursday Afternoon WSW 25-35
West North Ridgeline Winds (mph)
Wednesday Evening S 15-25
Wednesday Night SSE 20-30
Thursday Morning S 25-35
Thursday Afternoon WSW 15-25
West Central Ridgeline Winds (mph)
Wednesday Evening SE 10-20
Wednesday Night SE 15-25
Thursday Morning SSW 20-30
Thursday Afternoon WSW 25-35
West South Ridgeline Winds (mph)
Wednesday Evening SSW 20-30
Wednesday Night SSW 20-30
Thursday Morning WSW 30-40
Thursday Afternoon W 30-40
Stevens Pass Ridgeline Winds (mph)
Wednesday Evening SSE 5-15
Wednesday Night SE 15-25
Thursday Morning SE 15-25
Thursday Afternoon W 25-35
Snoqualmie Pass Ridgeline Winds (mph)
Wednesday Evening ESE 10-20
Wednesday Night SE 20-30
Thursday Morning SSW 15-25
Thursday Afternoon W 30-40
East North Ridgeline Winds (mph)
Wednesday Evening SSE 5-15
Wednesday Night SE 15-25
Thursday Morning S 10-20
Thursday Afternoon WSW 30-40
East Central Ridgeline Winds (mph)
Wednesday Evening SSW 15-25
Wednesday Night SSE 15-25
Thursday Morning SW 20-30
Thursday Afternoon W 35-50
East South Ridgeline Winds (mph)
Wednesday Evening SSW 10-20
Wednesday Night S 15-25
Thursday Morning WSW 25-35
Thursday Afternoon W 35-50
Mt. Hood Ridgeline Winds (mph)
Wednesday Evening SW 25-35
Wednesday Night SW 35-50
Thursday Morning WSW 35-50
Thursday Afternoon WSW 30-40

Extended Weather Synopsis

Active weather continues with a warm front moving over the area on Saturday for a slightly warmer system as a low tracks into British Columbia. Rain and snow shower activity continues in its wake as temperatures cool Saturday night. Cooler weather is on tap for Sunday as a low tracks into Oregon.

Extended Snow Level (ft)

Friday Night* Saturday * Saturday Night* Sunday *
West North 3500' 3500' 3000' 2500'
Snoqualmie Pass 3000' 4000' 3000' 3000'
Mt. Hood 5000' 4500' 4500' 4000'
West North Elevation
Friday Night* 3500'
Saturday * 3500'
Saturday Night* 3000'
Sunday * 2500'
Snoqualmie Pass Elevation
Friday Night* 3000'
Saturday * 4000'
Saturday Night* 3000'
Sunday * 3000'
Mt. Hood Elevation
Friday Night* 5000'
Saturday * 4500'
Saturday Night* 4500'
Sunday * 4000'

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

Previous forecast from Dec 25, 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’.