Issued: 2:03 PM PST Sunday, December 18, 2022
by Dennis D'Amico

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

Weather Synopsis

A broad trough over western Canada and the PNW continues to rotate showers inland this afternoon. Showers are heaviest where the moister Pacific air is overrunning very cold arctic air that's slowly seeping out through the Fraser River Valley and southward along the east slopes of the Cascades. Heavier showers can also be found aimed into the Mountain Loop area, where convergence bands have been pummelling the area relative to the rest of the region. Strong westerly ridgeline winds currently found in many locations this afternoon will continue through the evening. 

In general, the southward progression of convergence bands and the arctic air boundary have been behind schedule. That likely means a slightly longer duration of moderate snow showers this afternoon and evening for first Stevens, and then Snoqualmie Passes. Snow will not be confined to central-west Washington Cascades, most areas should pick up several inches of snow tonight with strong westerly ridgeline winds for the southern half of the forecast area. Overnight precipitation forecasts have been nudged upwards. 

Starting early Monday, strong westerly winds will ease. Showers will taper off as well and as we head into the day; Monday's showers should be isolated and light. High clouds from the next approaching sytem will begin to stream in during the afternoon.  We should see more sun than clouds up near the Canadian border for the north Cascades. Temperatures will be very cold for all areas save Mt. Hood. Bundle up, expect mid-mountain temperatures in the single digits to low teens tonight and Monday. 

Warm frontal moisture should arrive late Monday night into Tuesday as a developing low pressure system impacts the area. There are many details up in the air - forecast confidence is low regarding the track and precipitation amounts.  With some of the coldest air of the season over us, expect even modest water amounts to produce a healthy snowfall totals. 

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 scattered light snow showers. Very cold.
Monday Partly to mostly cloudy with isolated snow showers.
Sunday Night Mostly cloudy with scattered light snow showers. Very cold.
Monday Partly to mostly sunny. Chance of a snow shower. Very cold.
Sunday Night Light to moderate snow showers becoming mostly cloudy and scattered showers after midnight. Moderate ridgeline winds.
Monday Mostly cloudy with isolated snow showers.
Sunday Night Light to occasionally moderate snow showers becoming mostly cloudy and scattered showers late. Moderate to strong ridgeline winds.
Monday Mostly cloudy with isolated snow showers.
Sunday Night Light to moderate snow showers becoming mostly cloudy and scattered showers late. Moderate to strong westerly Pass level and ridgeline winds decreasing overnight.
Monday Mostly cloudy with isolated snow showers. Light to moderate west winds at Pass level easing in the morning.
Sunday Night Light to moderate snow showers becoming mostly cloudy and scattered showers late. Strong westerly Pass level and ridgeline winds decreasing overnight.
Monday Mostly cloudy with isolated snow showers.Moderate west winds at Pass level easing in the morning.
Sunday Night Mostly cloudy with scattered light snow showers.Very cold.
Monday Partly to mostly sunny. Chance of a snow shower. Very cold.
Sunday Night Cloudy with light snow showers in the evening, showers occationally moderate near the Crest. Then mostly cloudy with scattered light snow showers late. Moderate to strong ridgeline winds.
Monday Mostly cloudy with isolated snow showers. Very cold.
Sunday Night Cloudy with light snow showers, occasionally moderate near the Cascade crest in the evening.Moderate to strong ridgeline winds.
Monday Mostly cloudy with isolated snow showers.
Sunday Night Light snow showers. Strong to extreme winds.
Monday Mostly cloudy with light snow showers. Strong winds decreasing in the morning.

Issued: 2:03 PM PST Sunday, December 18, 2022

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

Issued: 2:03 PM PST Sunday, December 18, 2022

Snow Level (ft)

Sunday Evening Sunday Night Monday Morning Monday Afternoon Monday Evening* Monday Night* Tuesday Morning* Tuesday Afternoon*
Olympics 0 0 0 0 0 0 0 500'
West North 0 0 0 0 0 0 0 0
West Central 0 0 0 0 0 0 0 500'
West South 0 0 0 0 0 0 0 1000'
Stevens Pass 0 0 0 0 0 0 0 500'
Snoqualmie Pass 0 0 0 0 0 0 0 500'
East North 0 0 0 0 0 0 0 0
East Central 0 0 0 0 0 0 0 0
East South 500' 0 0 0 0 0 0 500'
Mt. Hood 2000' 1500' 1500' 1500' 1000' 1000' 1000' 1000'
Olympics Elevation
Sunday Evening 0'
Sunday Night 0'
Monday Morning 0'
Monday Afternoon 0'
Monday Evening* 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 500'
West North Elevation
Sunday Evening 0'
Sunday Night 0'
Monday Morning 0'
Monday Afternoon 0'
Monday Evening* 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 0'
West Central Elevation
Sunday Evening 0'
Sunday Night 0'
Monday Morning 0'
Monday Afternoon 0'
Monday Evening* 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 500'
West South Elevation
Sunday Evening 0'
Sunday Night 0'
Monday Morning 0'
Monday Afternoon 0'
Monday Evening* 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 1000'
Stevens Pass Elevation
Sunday Evening 0'
Sunday Night 0'
Monday Morning 0'
Monday Afternoon 0'
Monday Evening* 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 500'
Snoqualmie Pass Elevation
Sunday Evening 0'
Sunday Night 0'
Monday Morning 0'
Monday Afternoon 0'
Monday Evening* 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 500'
East North Elevation
Sunday Evening 0'
Sunday Night 0'
Monday Morning 0'
Monday Afternoon 0'
Monday Evening* 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 0'
East Central Elevation
Sunday Evening 0'
Sunday Night 0'
Monday Morning 0'
Monday Afternoon 0'
Monday Evening* 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 0'
East South Elevation
Sunday Evening 500'
Sunday Night 0'
Monday Morning 0'
Monday Afternoon 0'
Monday Evening* 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 500'
Mt. Hood Elevation
Sunday Evening 2000'
Sunday Night 1500'
Monday Morning 1500'
Monday Afternoon 1500'
Monday Evening* 1000'
Monday Night* 1000'
Tuesday Morning* 1000'
Tuesday Afternoon* 1000'

Issued: 2:03 PM PST Sunday, December 18, 2022

5000' Temperatures (°F)

Sunday Night Monday
Max / Min Max / Min
Olympics 13 / 6 15 / 5
West North 10 / 4 11 / 3
West Central 12 / 3 15 / 7
West South 17 / 8 18 / 10
Stevens Pass 15 / 5 13 / 5
Snoqualmie Pass 18 / 8 13 / 6
East North 8 / -3 7 / -4
East Central 17 / 9 13 / 6
East South 23 / 14 23 / 9
Mt. Hood 25 / 19 24 / 18
Olympics 5000' Temperature Forecast
(Max / Min)
Sunday Night 13 / 6
Monday 15 / 5
West North 5000' Temperature Forecast
(Max / Min)
Sunday Night 10 / 4
Monday 11 / 3
West Central 5000' Temperature Forecast
(Max / Min)
Sunday Night 12 / 3
Monday 15 / 7
West South 5000' Temperature Forecast
(Max / Min)
Sunday Night 17 / 8
Monday 18 / 10
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Sunday Night 15 / 5
Monday 13 / 5
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Sunday Night 18 / 8
Monday 13 / 6
East North 5000' Temperature Forecast
(Max / Min)
Sunday Night 8 / -3
Monday 7 / -4
East Central 5000' Temperature Forecast
(Max / Min)
Sunday Night 17 / 9
Monday 13 / 6
East South 5000' Temperature Forecast
(Max / Min)
Sunday Night 23 / 14
Monday 23 / 9
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Sunday Night 25 / 19
Monday 24 / 18

Issued: 2:03 PM PST Sunday, December 18, 2022

Ridgeline Winds (mph)

Sunday Evening Sunday Night Monday Morning Monday Afternoon
Olympics W 5-15 SW 5-15 SW 5-15 SW 5-15
West North W 0-10 VAR 5-15 SW 0-10 SW 0-10
West Central W 15-25 SW 5-15 SW 5-15 SW 0-10
West South W 25-35 WSW 15-25 W 5-15 WSW 5-15
Stevens Pass W 15-25 W 5-15 W 5-15 W 5-15
Snoqualmie Pass W 25-35 W 15-25 W 10-20 WSW 10-20
East North W 5-15 W 5-15 W 5-15 W 10-20
East Central W 25-35 W 15-25 W 10-20 W 10-20
East South W 20-30 WSW 10-20 W 10-20 W 5-15
Mt. Hood WSW 35-50 W 30-40 W 20-30 WSW 15-25
Olympics Ridgeline Winds (mph)
Sunday Evening W 5-15
Sunday Night SW 5-15
Monday Morning SW 5-15
Monday Afternoon SW 5-15
West North Ridgeline Winds (mph)
Sunday Evening W 0-10
Sunday Night VAR 5-15
Monday Morning SW 0-10
Monday Afternoon SW 0-10
West Central Ridgeline Winds (mph)
Sunday Evening W 15-25
Sunday Night SW 5-15
Monday Morning SW 5-15
Monday Afternoon SW 0-10
West South Ridgeline Winds (mph)
Sunday Evening W 25-35
Sunday Night WSW 15-25
Monday Morning W 5-15
Monday Afternoon WSW 5-15
Stevens Pass Ridgeline Winds (mph)
Sunday Evening W 15-25
Sunday Night W 5-15
Monday Morning W 5-15
Monday Afternoon W 5-15
Snoqualmie Pass Ridgeline Winds (mph)
Sunday Evening W 25-35
Sunday Night W 15-25
Monday Morning W 10-20
Monday Afternoon WSW 10-20
East North Ridgeline Winds (mph)
Sunday Evening W 5-15
Sunday Night W 5-15
Monday Morning W 5-15
Monday Afternoon W 10-20
East Central Ridgeline Winds (mph)
Sunday Evening W 25-35
Sunday Night W 15-25
Monday Morning W 10-20
Monday Afternoon W 10-20
East South Ridgeline Winds (mph)
Sunday Evening W 20-30
Sunday Night WSW 10-20
Monday Morning W 10-20
Monday Afternoon W 5-15
Mt. Hood Ridgeline Winds (mph)
Sunday Evening WSW 35-50
Sunday Night W 30-40
Monday Morning W 20-30
Monday Afternoon WSW 15-25

Issued: 2:03 PM PST Sunday, December 18, 2022

Extended Weather Synopsis

The Tuesday system should quickly push eastward leaving us with showers Tuesday night.  On Wednesday, even colder air should settle into the region, with widespread temperatures in the single digits.  Strong offshore flow may develop Wednesday night and Thursday, adding a strong ripping easterly wind to the mix. The next Pacific frontal system may arrive on Thursday, bringing widespread snow to the mountains once again. 

Extended Snow Level (ft)

Tuesday Night Wednesday * Wednesday Night* Thursday *
West North 0 0 0 0
Snoqualmie Pass 500' 0 0 0
Mt. Hood 2500' 2500' 0 0
West North Elevation
Tuesday Night 0'
Wednesday * 0'
Wednesday Night* 0'
Thursday * 0'
Snoqualmie Pass Elevation
Tuesday Night 500'
Wednesday * 0'
Wednesday Night* 0'
Thursday * 0'
Mt. Hood Elevation
Tuesday Night 2500'
Wednesday * 2500'
Wednesday Night* 0'
Thursday * 0'

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

Previous forecast from Dec 18, 2022

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’.