Issued: 2:15 PM PST Sunday, December 17, 2023
by Robert Hahn

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

Weather Synopsis

The ridge that continues to bring our region unseasonably mild and dry weather gradually shifts eastward Sunday night. Freezing levels brush the volcanoes, sitting in the 8000-11000 ft range. SSW flow aloft brings moisture from a cutoff low ejecting northward in a series of shortwave features. The first feature rounds the top of the ridge in the early morning hours on Monday and could bring a few sprinkles to the Olympics and perhaps the Mt Baker area. The second more significant wave brings more widespread light rain, high elevation snow as it spreads into areas south of I-90 and the Olympics on Monday. Winds increase into light to moderate range for these areas late in the day.

Meanwhile, low-level moderate E winds continue to slosh colder up against the east slopes of the Cascades. This flow will create an interesting scenario as the precipitation expands northward Monday night, with a wintry mix likely developing in the passes. Snoqualmie Pass and Stevens Pass could start as freezing rain Monday evening, switch to snow as the cold air pool deepens overnight into Tuesday morning, and then switch back to rain or freezing rain sometime Tuesday afternoon as a second shortwave feature lifting northward passes through. Precipitation should be primarily snow for Washington Pass.

 

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 Mostly cloudy with a chance of light rain in the early morning hours. Light to occasionally moderate ridgeline winds. Unseasonably mild.
Monday Cloudy with increasing chances of light rain. Increasing light to occasionally moderate ridgeline winds. Mild.
Sunday Night Mostly cloudy with a slight chance of light rain in the early morning hours. Light to occasionally moderate ridgeline winds. Unseasonably mild.
Monday Cloudy with chances for light rain late in the day. Increasing light ridgeline winds. Mild.
Sunday Night Mostly cloudy. Light to occasionally moderate ridgeline winds. Unseasonably mild.
Monday Cloudy with a slight chance of light rain late in the day. Increasing light ridgeline winds. Mild.
Sunday Night Mostly cloudy. Light to occasionally moderate ridgeline winds. Unseasonably mild.
Monday Cloudy with a chance of light rain late in the day. Increasing light ridgeline winds may become moderate at times near the mountain gaps. Mild.
Sunday Night Mostly cloudy. Light to moderate ridgeline winds. Light to moderate E winds at the Pass. Unseasonably mild at ridgelines, but below or near freezing at the Pass.
Monday Cloudy. Light to moderate ridgeline winds. Light to moderate E winds at the Pass. Inversion likely present.
Sunday Night Mostly cloudy. Light to moderate ridgeline winds. Moderate E winds at the Pass. Unseasonably mild at ridgelines, but below or near freezing at the Pass.
Monday Cloudy with a slight chance of rain or wintry mix late in the day. Light to moderate ridgeline winds. Moderate E winds at the Pass. Inversion likely present.
Sunday Night Mostly cloudy. Light ridgeline winds. Mild near ridgelines with a strong low-level inversion.
Monday Cloudy. Light ridgeline winds. Mild near ridgelines with a strong low-level inversion.
Sunday Night Mostly cloudy. Light to occasionally moderate ridgeline winds. Mild near ridgelines with a low-level inversion.
Monday Cloudy with a chance of light snow or wintry mix developing late in the day. Light ridgeline winds.
Sunday Night Mostly cloudy. Increasing light ridgeline winds. Mild nea ridgelines with a low-level inversion.
Monday Cloudy with a chance of light snow or wintry mix developing late in the day. Light ridgeline winds.
Sunday Night Cloudy. Light to moderate ridgeline winds. Mild.
Monday Cloudy with periods of light rain and high-elevation snow. Increasing light to moderate ridgeline winds.

Issued: 2:15 PM PST Sunday, December 17, 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 LT 0.10 LT 0.10 0.25 LT 0.25
Mt Baker Ski Area 0 LT 0.10 0.25 0.25 - 0.50
Mt. Loop - Barlow Pass 0 0 LT 0.25 0.25
Stevens Pass 0 0 LT 0.25 LT 0.25
Snoqualmie Pass 0 0 LT 0.25 0.25
Crystal Mt 0 LT 0.10 0.25 0.25
Paradise 0 LT 0.10 0.25 0.25 - 0.50
White Pass 0 LT 0.10 LT 0.25 LT 0.25
Washington Pass 0 0 LT 0.10 LT 0.25
Mission Ridge 0 0 LT 0.25 LT 0.10
Salmon la Sac - Gallagher Head 0 LT 0.10 LT 0.25 0.25
Tieton River - Darland Mt. 0 LT 0.10 LT 0.25 LT 0.25
Mt Hood Meadows 0 LT 0.25 LT 0.25 0.25
Timberline 0 LT 0.25 0.25 0.25
Hurricane Ridge Precipitation (in)
Sunday Night LT 0.10
Monday LT 0.10
Monday Night 0.25
Tuesday LT 0.25
Mt Baker Ski Area Precipitation (in)
Sunday Night 0
Monday LT 0.10
Monday Night 0.25
Tuesday 0.25 - 0.50
Mt. Loop - Barlow Pass Precipitation (in)
Sunday Night 0
Monday 0
Monday Night LT 0.25
Tuesday 0.25
Stevens Pass Precipitation (in)
Sunday Night 0
Monday 0
Monday Night LT 0.25
Tuesday LT 0.25
Snoqualmie Pass Precipitation (in)
Sunday Night 0
Monday 0
Monday Night LT 0.25
Tuesday 0.25
Crystal Mt Precipitation (in)
Sunday Night 0
Monday LT 0.10
Monday Night 0.25
Tuesday 0.25
Paradise Precipitation (in)
Sunday Night 0
Monday LT 0.10
Monday Night 0.25
Tuesday 0.25 - 0.50
White Pass Precipitation (in)
Sunday Night 0
Monday LT 0.10
Monday Night LT 0.25
Tuesday LT 0.25
Washington Pass Precipitation (in)
Sunday Night 0
Monday 0
Monday Night LT 0.10
Tuesday LT 0.25
Mission Ridge Precipitation (in)
Sunday Night 0
Monday 0
Monday Night LT 0.25
Tuesday LT 0.10
Salmon la Sac - Gallagher Head Precipitation (in)
Sunday Night 0
Monday LT 0.10
Monday Night LT 0.25
Tuesday 0.25
Tieton River - Darland Mt. Precipitation (in)
Sunday Night 0
Monday LT 0.10
Monday Night LT 0.25
Tuesday LT 0.25
Mt Hood Meadows Precipitation (in)
Sunday Night 0
Monday LT 0.25
Monday Night LT 0.25
Tuesday 0.25
Timberline Precipitation (in)
Sunday Night 0
Monday LT 0.25
Monday Night 0.25
Tuesday 0.25

Issued: 2:15 PM PST Sunday, December 17, 2023

Snow Level (ft)

Sunday Evening* Sunday Night* Monday Morning* Monday Afternoon* Monday Evening* Monday Night* Tuesday Morning* Tuesday Afternoon*
Olympics 10000' 9000' 8500' 7500' 7000' 6500' 6500' 6500'
West North 9000' 9000' 8500' 7000' 6500' 6500' 6000' 5500'
West Central 9000' 9000' 8500' 7500' 6500' 5500' 5500' 5000'
West South 10500' 10000' 8500' 7500' 7000' 5000' 4500' 5500'
Stevens Pass 9500' 9000' 8500' 6000' 3000' 2500' 2500' 4000'
Snoqualmie Pass 10000' 9500' 8500' 7000' 6000' 3000' 3000' 4000'
East North 8500' 8000' 3000' 3000' 1000' 1000' 1000' 2500'
East Central 9500' 8500' 8000' 5000' 3000' 2500' 2500' 3500'
East South 10500' 9500' 8500' 7000' 5000' 3000' 3500' 5500'
Mt. Hood 11000' 10000' 9000' 8000' 6500' 6000' 6000' 6500'
Olympics Elevation
Sunday Evening* 10000'
Sunday Night* 9000'
Monday Morning* 8500'
Monday Afternoon* 7500'
Monday Evening* 7000'
Monday Night* 6500'
Tuesday Morning* 6500'
Tuesday Afternoon* 6500'
West North Elevation
Sunday Evening* 9000'
Sunday Night* 9000'
Monday Morning* 8500'
Monday Afternoon* 7000'
Monday Evening* 6500'
Monday Night* 6500'
Tuesday Morning* 6000'
Tuesday Afternoon* 5500'
West Central Elevation
Sunday Evening* 9000'
Sunday Night* 9000'
Monday Morning* 8500'
Monday Afternoon* 7500'
Monday Evening* 6500'
Monday Night* 5500'
Tuesday Morning* 5500'
Tuesday Afternoon* 5000'
West South Elevation
Sunday Evening* 10500'
Sunday Night* 10000'
Monday Morning* 8500'
Monday Afternoon* 7500'
Monday Evening* 7000'
Monday Night* 5000'
Tuesday Morning* 4500'
Tuesday Afternoon* 5500'
Stevens Pass Elevation
Sunday Evening* 9500'
Sunday Night* 9000'
Monday Morning* 8500'
Monday Afternoon* 6000'
Monday Evening* 3000'
Monday Night* 2500'
Tuesday Morning* 2500'
Tuesday Afternoon* 4000'
Snoqualmie Pass Elevation
Sunday Evening* 10000'
Sunday Night* 9500'
Monday Morning* 8500'
Monday Afternoon* 7000'
Monday Evening* 6000'
Monday Night* 3000'
Tuesday Morning* 3000'
Tuesday Afternoon* 4000'
East North Elevation
Sunday Evening* 8500'
Sunday Night* 8000'
Monday Morning* 3000'
Monday Afternoon* 3000'
Monday Evening* 1000'
Monday Night* 1000'
Tuesday Morning* 1000'
Tuesday Afternoon* 2500'
East Central Elevation
Sunday Evening* 9500'
Sunday Night* 8500'
Monday Morning* 8000'
Monday Afternoon* 5000'
Monday Evening* 3000'
Monday Night* 2500'
Tuesday Morning* 2500'
Tuesday Afternoon* 3500'
East South Elevation
Sunday Evening* 10500'
Sunday Night* 9500'
Monday Morning* 8500'
Monday Afternoon* 7000'
Monday Evening* 5000'
Monday Night* 3000'
Tuesday Morning* 3500'
Tuesday Afternoon* 5500'
Mt. Hood Elevation
Sunday Evening* 11000'
Sunday Night* 10000'
Monday Morning* 9000'
Monday Afternoon* 8000'
Monday Evening* 6500'
Monday Night* 6000'
Tuesday Morning* 6000'
Tuesday Afternoon* 6500'

Issued: 2:15 PM PST Sunday, December 17, 2023

5000' Temperatures (°F)

Sunday Night Monday
Max / Min Max / Min
Olympics 46 / 40 42 / 38
West North 44 / 40 42 / 38
West Central 44 / 39 41 / 37
West South 45 / 39 43 / 35
Stevens Pass 39 / 35 37 / 33
Snoqualmie Pass 40 / 36 37 / 33
East North 25 / 20 26 / 18
East Central 37 / 32 36 / 31
East South 39 / 35 38 / 33
Mt. Hood 44 / 38 42 / 38
Olympics 5000' Temperature Forecast
(Max / Min)
Sunday Night 46 / 40
Monday 42 / 38
West North 5000' Temperature Forecast
(Max / Min)
Sunday Night 44 / 40
Monday 42 / 38
West Central 5000' Temperature Forecast
(Max / Min)
Sunday Night 44 / 39
Monday 41 / 37
West South 5000' Temperature Forecast
(Max / Min)
Sunday Night 45 / 39
Monday 43 / 35
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Sunday Night 39 / 35
Monday 37 / 33
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Sunday Night 40 / 36
Monday 37 / 33
East North 5000' Temperature Forecast
(Max / Min)
Sunday Night 25 / 20
Monday 26 / 18
East Central 5000' Temperature Forecast
(Max / Min)
Sunday Night 37 / 32
Monday 36 / 31
East South 5000' Temperature Forecast
(Max / Min)
Sunday Night 39 / 35
Monday 38 / 33
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Sunday Night 44 / 38
Monday 42 / 38

Issued: 2:15 PM PST Sunday, December 17, 2023

Ridgeline Winds (mph)

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

Issued: 2:15 PM PST Sunday, December 17, 2023

Extended Weather Synopsis

Precipitation winds down from south to north Tuesday evening through Wednesday morning with fair weather and light winds aloft as another cutoff low moves just off the California coast. Freezing levels west of the Cascade Crest lower into the 5000-6500 ft range Tuesday into Wednesday. A system approaching form the north will keep the northern half of our forecast region cloudy Wednesday night and Thursday.

Extended Snow Level (ft)

Tuesday Night* Wednesday * Wednesday Night* Thursday *
West North 6000' 5500' 6500' 5500'
Snoqualmie Pass 5000' 7000' 7500' 7000'
Mt. Hood 6500' 8000' 8500' 8500'
West North Elevation
Tuesday Night* 6000'
Wednesday * 5500'
Wednesday Night* 6500'
Thursday * 5500'
Snoqualmie Pass Elevation
Tuesday Night* 5000'
Wednesday * 7000'
Wednesday Night* 7500'
Thursday * 7000'
Mt. Hood Elevation
Tuesday Night* 6500'
Wednesday * 8000'
Wednesday Night* 8500'
Thursday * 8500'

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

Previous forecast from Dec 17, 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’.