Issued: 2:03 PM PST Sunday, December 31, 2023
by Dennis D'Amico

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

Weather Synopsis

We have a mix of sun and low clouds across the region this afternoon with mid-mountain temperatures generally in the 30s. A weak weather disturbance will traverse from west to east tonight spreading some high cover inland.  A frontal system will approach the coast on Monday. This feature will increase offshore flow/easterly winds and start to drag low clouds along the east slopes of the Cascades towards the Cascade Passes.  It will also spread thicker high clouds inland during the afternoon. We'll see a mild and mostly sunny start to 2024 along the Olympics, Mt Hood and the west slopes of the Cascades and for mid/upper slopes near the Cascade Passes and along the east slopes of the Cascades low clouds and cooler temperatures lower slopes and clear skies for upper slopes. 

The system will weaken as it nears the coast Monday night and Tuesday, eventually shearing apart.  We may see some light rain and snow glance the Olympics while light precipitation will struggle to reach the surface over the Cascades and Mt Hood where the mid levels are drier. Areas with low clouds will persist into Tuesday.  E-SE winds will pick up Monday night and Tuesday, so look for breezy to locally windy conditions to develop as well. Temperatures will be cooler near and east of the Cascade crest during this period versus areas futher west. 

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 Partly to mostly cloudy with high clouds.
Monday Mostly sunny in the morning then becoming partly sunny with high clouds increasing in the afternoon.
Sunday Night Partly to mostly cloudy with high clouds.
Monday Mostly sunny in the morning then becoming partly sunny with high clouds increasing in the afternoon. Moderate ridgeline winds in the afternoon.
Sunday Night Partly to mostly cloudy with high clouds.
Monday Mostly sunny in the morning then becoming partly sunny with high clouds increasing in the afternoon. Moderate ridgeline winds in the afternoon.
Sunday Night Partly to mostly cloudy with high clouds. Areas of low clouds near White Pass.
Monday Mostly sunny in the morning then becoming partly sunny with high clouds increasing in the afternoon. Areas of low clouds and cooler near White Pass. Moderate ridgeline winds in the afternoon.
Sunday Night Mostly cloudy with high clouds and areas of low clouds lower slopes near and east of the Pass. Light east winds at Pass level, variable and light winds at ridgeline.
Monday Areas of low clouds near and east of the Pass, mostly sunny upper slopes. Light to moderate E Pass level and ridgeline winds developing in the afternoon.
Sunday Night Mostly cloudy with high clouds and areas of low clouds lower slopes near and east of the Pass. Light east winds at Pass level, variable and light winds at ridgeline.
Monday Areas of low clouds near and east of the Pass, mostly sunny upper slopes. Moderate E Pass level and ridgeline winds developing in the afternoon.
Sunday Night Mostly cloudy with high clouds and areas of low clouds lower slopes and valleys.
Monday Areas of low clouds lower slopes and valleys, mostly sunny upper slopes.
Sunday Night Mostly cloudy with high clouds and areas of low clouds lower slopes and valleys.
Monday Areas of low clouds lower slopes and valleys, mostly sunny upper slopes.
Sunday Night Mostly cloudy with high clouds and areas of low clouds lower slopes and valleys.
Monday Areas of low clouds lower slopes and valleys, mostly sunny upper slopes.
Sunday Night Partly to mostly cloudy with high clouds
Monday Mostly sunny in the morning then becoming partly sunny with high clouds increasing in the afternoon.

Issued: 2:03 PM PST Sunday, December 31, 2023

Precipitation (in)

Sunday Night Monday Monday Night Tuesday
4 pm - 4 am 4 am - 4 pm 4 pm - 4 am 4 am - 4 pm
Hurricane Ridge 0 0 0 LT 0.10
Mt Baker Ski Area 0 0 0 0
Mt. Loop - Barlow Pass 0 0 0 0
Stevens Pass 0 0 0 0
Snoqualmie Pass 0 0 0 0
Crystal Mt 0 0 0 0
Paradise 0 0 0 0
White Pass 0 0 0 0
Washington Pass 0 0 0 0
Mission Ridge 0 0 0 0
Salmon la Sac - Gallagher Head 0 0 0 0
Tieton River - Darland Mt. 0 0 0 0
Mt Hood Meadows 0 0 0 0
Timberline 0 0 0 0
Hurricane Ridge Precipitation (in)
Sunday Night 0
Monday 0
Monday Night 0
Tuesday LT 0.10
Mt Baker Ski Area Precipitation (in)
Sunday Night 0
Monday 0
Monday Night 0
Tuesday 0
Mt. Loop - Barlow Pass Precipitation (in)
Sunday Night 0
Monday 0
Monday Night 0
Tuesday 0
Stevens Pass Precipitation (in)
Sunday Night 0
Monday 0
Monday Night 0
Tuesday 0
Snoqualmie Pass Precipitation (in)
Sunday Night 0
Monday 0
Monday Night 0
Tuesday 0
Crystal Mt Precipitation (in)
Sunday Night 0
Monday 0
Monday Night 0
Tuesday 0
Paradise Precipitation (in)
Sunday Night 0
Monday 0
Monday Night 0
Tuesday 0
White Pass Precipitation (in)
Sunday Night 0
Monday 0
Monday Night 0
Tuesday 0
Washington Pass Precipitation (in)
Sunday Night 0
Monday 0
Monday Night 0
Tuesday 0
Mission Ridge Precipitation (in)
Sunday Night 0
Monday 0
Monday Night 0
Tuesday 0
Salmon la Sac - Gallagher Head Precipitation (in)
Sunday Night 0
Monday 0
Monday Night 0
Tuesday 0
Tieton River - Darland Mt. Precipitation (in)
Sunday Night 0
Monday 0
Monday Night 0
Tuesday 0
Mt Hood Meadows Precipitation (in)
Sunday Night 0
Monday 0
Monday Night 0
Tuesday 0
Timberline Precipitation (in)
Sunday Night 0
Monday 0
Monday Night 0
Tuesday 0

Issued: 2:03 PM PST Sunday, December 31, 2023

Snow Level (ft)

Sunday Evening Sunday Night* Monday Morning* Monday Afternoon* Monday Evening* Monday Night* Tuesday Morning* Tuesday Afternoon*
Olympics 4000' 3500' 4000' 5000' 5500' 6000' 6000' 5500'
West North 3500' 3000' 3500' 4500' 5000' 5500' 5500' 6000'
West Central 3500' 2500' 3500' 4500' 4500' 4500' 4500' 4500'
West South 3500' 2500' 3500' 4500' 4000' 3500' 3500' 4000'
Stevens Pass 3000' 2000' 2500' 3000' 2500' 2000' 2500' 3000'
Snoqualmie Pass 3000' 2500' 3000' 3500' 3000' 2500' 3000' 3500'
East North 2500' 1500' 2000' 3000' 2500' 1500' 2000' 3000'
East Central 2500' 1500' 2000' 3000' 2500' 1500' 2000' 3000'
East South 3500' 2000' 2500' 3500' 2500' 2000' 2500' 4000'
Mt. Hood 5000' 5000' 5500' 6000' 6000' 6000' 5500' 4500'
Olympics Elevation
Sunday Evening 4000'
Sunday Night* 3500'
Monday Morning* 4000'
Monday Afternoon* 5000'
Monday Evening* 5500'
Monday Night* 6000'
Tuesday Morning* 6000'
Tuesday Afternoon* 5500'
West North Elevation
Sunday Evening 3500'
Sunday Night* 3000'
Monday Morning* 3500'
Monday Afternoon* 4500'
Monday Evening* 5000'
Monday Night* 5500'
Tuesday Morning* 5500'
Tuesday Afternoon* 6000'
West Central Elevation
Sunday Evening 3500'
Sunday Night* 2500'
Monday Morning* 3500'
Monday Afternoon* 4500'
Monday Evening* 4500'
Monday Night* 4500'
Tuesday Morning* 4500'
Tuesday Afternoon* 4500'
West South Elevation
Sunday Evening 3500'
Sunday Night* 2500'
Monday Morning* 3500'
Monday Afternoon* 4500'
Monday Evening* 4000'
Monday Night* 3500'
Tuesday Morning* 3500'
Tuesday Afternoon* 4000'
Stevens Pass Elevation
Sunday Evening 3000'
Sunday Night* 2000'
Monday Morning* 2500'
Monday Afternoon* 3000'
Monday Evening* 2500'
Monday Night* 2000'
Tuesday Morning* 2500'
Tuesday Afternoon* 3000'
Snoqualmie Pass Elevation
Sunday Evening 3000'
Sunday Night* 2500'
Monday Morning* 3000'
Monday Afternoon* 3500'
Monday Evening* 3000'
Monday Night* 2500'
Tuesday Morning* 3000'
Tuesday Afternoon* 3500'
East North Elevation
Sunday Evening 2500'
Sunday Night* 1500'
Monday Morning* 2000'
Monday Afternoon* 3000'
Monday Evening* 2500'
Monday Night* 1500'
Tuesday Morning* 2000'
Tuesday Afternoon* 3000'
East Central Elevation
Sunday Evening 2500'
Sunday Night* 1500'
Monday Morning* 2000'
Monday Afternoon* 3000'
Monday Evening* 2500'
Monday Night* 1500'
Tuesday Morning* 2000'
Tuesday Afternoon* 3000'
East South Elevation
Sunday Evening 3500'
Sunday Night* 2000'
Monday Morning* 2500'
Monday Afternoon* 3500'
Monday Evening* 2500'
Monday Night* 2000'
Tuesday Morning* 2500'
Tuesday Afternoon* 4000'
Mt. Hood Elevation
Sunday Evening 5000'
Sunday Night* 5000'
Monday Morning* 5500'
Monday Afternoon* 6000'
Monday Evening* 6000'
Monday Night* 6000'
Tuesday Morning* 5500'
Tuesday Afternoon* 4500'

Issued: 2:03 PM PST Sunday, December 31, 2023

5000' Temperatures (°F)

Sunday Night Monday
Max / Min Max / Min
Olympics 29 / 27 33 / 27
West North 28 / 26 32 / 27
West Central 28 / 26 33 / 27
West South 28 / 26 33 / 27
Stevens Pass 27 / 25 31 / 26
Snoqualmie Pass 28 / 26 31 / 27
East North 26 / 22 30 / 25
East Central 26 / 24 30 / 26
East South 27 / 25 33 / 26
Mt. Hood 32 / 29 37 / 31
Olympics 5000' Temperature Forecast
(Max / Min)
Sunday Night 29 / 27
Monday 33 / 27
West North 5000' Temperature Forecast
(Max / Min)
Sunday Night 28 / 26
Monday 32 / 27
West Central 5000' Temperature Forecast
(Max / Min)
Sunday Night 28 / 26
Monday 33 / 27
West South 5000' Temperature Forecast
(Max / Min)
Sunday Night 28 / 26
Monday 33 / 27
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Sunday Night 27 / 25
Monday 31 / 26
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Sunday Night 28 / 26
Monday 31 / 27
East North 5000' Temperature Forecast
(Max / Min)
Sunday Night 26 / 22
Monday 30 / 25
East Central 5000' Temperature Forecast
(Max / Min)
Sunday Night 26 / 24
Monday 30 / 26
East South 5000' Temperature Forecast
(Max / Min)
Sunday Night 27 / 25
Monday 33 / 26
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Sunday Night 32 / 29
Monday 37 / 31

Issued: 2:03 PM PST Sunday, December 31, 2023

Ridgeline Winds (mph)

Sunday Evening Sunday Night Monday Morning Monday Afternoon
Olympics S 0-10 S 0-10 S 5-15 S 10-20
West North VAR 0-10 S 0-10 S 5-15 S 10-20
West Central VAR 0-10 SW 0-10 S 0-10 S 5-15
West South VAR 0-10 S 0-10 S 5-15 SSE 10-20
Stevens Pass VAR 0-10 S 0-10 SSE 0-10 SSE 5-15
Snoqualmie Pass WNW 0-10 S 0-10 SSE 5-15 SSE 10-20
East North WSW 0-10 SW 0-10 S 0-10 S 5-15
East Central WSW 0-10 SSW 5-15 SSW 0-10 S 5-15
East South SW 0-10 SSW 0-10 SSW 0-10 S 5-15
Mt. Hood SW 0-10 SW 5-15 SW 5-15 SSW 5-15
Olympics Ridgeline Winds (mph)
Sunday Evening S 0-10
Sunday Night S 0-10
Monday Morning S 5-15
Monday Afternoon S 10-20
West North Ridgeline Winds (mph)
Sunday Evening VAR 0-10
Sunday Night S 0-10
Monday Morning S 5-15
Monday Afternoon S 10-20
West Central Ridgeline Winds (mph)
Sunday Evening VAR 0-10
Sunday Night SW 0-10
Monday Morning S 0-10
Monday Afternoon S 5-15
West South Ridgeline Winds (mph)
Sunday Evening VAR 0-10
Sunday Night S 0-10
Monday Morning S 5-15
Monday Afternoon SSE 10-20
Stevens Pass Ridgeline Winds (mph)
Sunday Evening VAR 0-10
Sunday Night S 0-10
Monday Morning SSE 0-10
Monday Afternoon SSE 5-15
Snoqualmie Pass Ridgeline Winds (mph)
Sunday Evening WNW 0-10
Sunday Night S 0-10
Monday Morning SSE 5-15
Monday Afternoon SSE 10-20
East North Ridgeline Winds (mph)
Sunday Evening WSW 0-10
Sunday Night SW 0-10
Monday Morning S 0-10
Monday Afternoon S 5-15
East Central Ridgeline Winds (mph)
Sunday Evening WSW 0-10
Sunday Night SSW 5-15
Monday Morning SSW 0-10
Monday Afternoon S 5-15
East South Ridgeline Winds (mph)
Sunday Evening SW 0-10
Sunday Night SSW 0-10
Monday Morning SSW 0-10
Monday Afternoon S 5-15
Mt. Hood Ridgeline Winds (mph)
Sunday Evening SW 0-10
Sunday Night SW 5-15
Monday Morning SW 5-15
Monday Afternoon SSW 5-15

Issued: 2:03 PM PST Sunday, December 31, 2023

Extended Weather Synopsis

There's a chance we'll receive some light precipitation Tuesday night through Wednesday as the weak frontal system passes through. At the very least, offshore E-SE winds will decrease on Wednesday. An upper level ridge of high pressure will briefly build later Wednesday, before flattening on Thursday as another frontal system approaches. This should open the door to a more weather pattern although forecast models are in poor agreement on how the pattern evolves.  

Extended Snow Level (ft)

Tuesday Night* Wednesday * Wednesday Night Thursday
West North 5500' 5000' 4000' 4000'
Snoqualmie Pass 3000' 4000' 4000' 4000'
Mt. Hood 3000' 4000' 4000' 4500'
West North Elevation
Tuesday Night* 5500'
Wednesday * 5000'
Wednesday Night 4000'
Thursday 4000'
Snoqualmie Pass Elevation
Tuesday Night* 3000'
Wednesday * 4000'
Wednesday Night 4000'
Thursday 4000'
Mt. Hood Elevation
Tuesday Night* 3000'
Wednesday * 4000'
Wednesday Night 4000'
Thursday 4500'

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

Previous forecast from Dec 31, 2023

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’.