Issued: 2:21 PM PST Thursday, November 21, 2024
by Dennis D'Amico

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

Weather Synopsis

Another deep low pressure positioned offshore will deepen rapidly tonight and produce a stormy conditions for our mountains.  Warm frontal precipitation will lift north overnight through OR and southern WA and spread precipitation toward the Canadian border around sunrise.  The low will briefly tap into subtropical moisture, aka an old atmospheric river boundary over inland NW and CA/OR, but significant moisture will be cut-off by Friday morning keeping this from being an exceptionally wet storm.  

E-SE winds will ramp up once again tonight with strong E-SE becoming strong S-SW on Friday morning in many areas.  Tonight through early Friday, the strongest E-SE will favor the central/southern WA Cascades and Passes, and then the post-frontal S-SW winds will be strongest over the Olympics and Mt Baker area Friday afternoon.

Unfortunately, this system will feature a warming trend with snow levels rising rapidly over Mt Hood tonight. Easterly flow through the Passes will help keep snow levels lower initially, but the WA Cascades will likely warm to 4500-5500' by Friday afternoon.  Precipitation totals will be highest along the east slopes of the Cascades with along the southern WA Cascades in general with storm WE totals of 1.00" or more.  Snow will transition to rain more quickly for Mt Hood and at mid-elevations along the west slopes of the Cascades south of I-90 Friday morning. As precipitation tapers Friday afternoon, we'll see a mix of sun and clouds for the latter half of the day. 

The same low pressure system will be like a house guest that just won't leave...hanging around offshore and continuing to send weak impulses (bands of showers) inland  on Saturday and making it difficult to pinpoint timing or cloud cover over the region. Plan for periods of wet weather and 3000-4000' snow levels, with the showers most likely to pepper the Olympic peninsula in this pattern. 

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 Chance of rain or snow showers in the evening, then light rain or snow developing after midnight and increasing late. Moderate ridgeline winds developing late.
Friday Light to occasionally moderate rain and snow in the morning, then mostly cloudy with scattered rain and snow showers in the afternoon. Strong ridgeline winds.
Thursday Night Mostly cloudy with a chance of rain or snow showers.
Friday Light to moderate rain and snow in the morning, then mostly cloudy with scattered light rain and snow showers in the afternoon. Strong ridgeline winds.
Thursday Night Mostly cloudy with a chance of rain or snow showers becoming cloudy with light rain and snow developing late tonight. Moderate ridgeline winds developing late tonight.
Friday Light to occasionally moderate rain and snow in the morning, then mostly cloudy with scattered light rain and snow showers in the afternoon. Strong ridgeline winds decreasing in the afternoon.
Thursday Night Mostly cloudy with a chance of rain or snow showers becoming cloudy with light rain and snow developing around midnight. Strong ridgelines developing around midnight.
Friday Light to occasionally moderate rain and snow in the morning, then mostly cloudy with scattered light rain and snow showers in the afternoon. Moderate E-SE winds becoming S-SW in the afternoon.
Thursday Night Mostly cloudy with a chance of rain or snow showers becoming cloudy with light snow developing late tonight. Moderate E-SE Pass level and ridgeline winds developing overnight.
Friday Light to occasionally moderate rain and snow in the morning, then mostly cloudy with scattered light rain and snow showers in the afternoon. Moderate E-SE winds becoming S-SW in the afternoon.
Thursday Night Mostly cloudy with a chance of rain or snow showers becoming cloudy with light snow developing late tonight. Moderate to strong E-SE Pass level and ridgeline winds developing overnight.
Friday Light to occasionally moderate rain and snow in the morning, then mostly cloudy with scattered light rain and snow showers in the afternoon. Moderate E-SE winds becoming S-SW in the afternoon.
Thursday Night Mostly cloudy with a chance of rain or snow showers becoming cloudy with light rain and snow developing late tonight.
Friday Light to moderate rain and snow in the morning, then mostly cloudy with scattered light rain and snow showers in the afternoon. Moderate to strong ridgeline winds easing in the afternoon.
Thursday Night Mostly cloudy with a chance of rain or snow showers becoming cloudy with light snow developing after midnight. Moderate ridgeline winds developing overnight.
Friday Light to moderate rain and snow in the morning, then mostly cloudy with scattered light rain and snow showers early in the afternoon. Moderate to strong ridgeline winds easing in the afternoon.
Thursday Night Mostly cloudy with a chance of rain or snow showers becoming cloudy with light snow developing late this evening. Moderate ridgeline winds developing overnight.
Friday Light to moderate rain and snow in the morning, then mostly cloudy with scattered light rain and snow showers early in the afternoon. Moderate to strong ridgeline winds easing in the afternoon.
Thursday Night Mostly cloudy with a chance of rain or snow showers becoming cloudy with light snow developing late this evening. Moderate ridgeline winds becoming strong overnight.
Friday Light to moderate rain and snow in the morning, then mostly cloudy with scattered light to occasionally moderate rain and snow showers early in the afternoon. Moderate to strong ridgeline winds.

Issued: 2:21 PM PST Thursday, November 21, 2024

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

Issued: 2:21 PM PST Thursday, November 21, 2024

Snow Level (ft)

Thursday Evening* Thursday Night* Friday Morning* Friday Afternoon* Friday Evening* Friday Night* Saturday Morning Saturday Afternoon
Olympics 4000' 4500' 5500' 5000' 4500' 4000' 3500' 3500'
West North 3500' 3500' 3500' 4500' 4500' 4000' 3500' 4000'
West Central 3500' 3500' 4000' 5000' 4500' 3500' 3500' 4000'
West South 4000' 4000' 5000' 5500' 4500' 3000' 3500' 4000'
Stevens Pass 3000' 3000' 3500' 4500' 4500' 3000' 3500' 4000'
Snoqualmie Pass 3500' 3000' 4000' 5000' 4500' 3500' 3500' 4000'
East North 2000' 2500' 3000' 4500' 4500' 2500' 3500' 4000'
East Central 3000' 2500' 3000' 4500' 4500' 3000' 3500' 4000'
East South 3500' 3500' 4500' 5000' 4500' 3500' 3500' 4000'
Mt. Hood 6000' 8000' 8000' 6500' 5000' 4500' 3500' 4000'
Olympics Elevation
Thursday Evening* 4000'
Thursday Night* 4500'
Friday Morning* 5500'
Friday Afternoon* 5000'
Friday Evening* 4500'
Friday Night* 4000'
Saturday Morning 3500'
Saturday Afternoon 3500'
West North Elevation
Thursday Evening* 3500'
Thursday Night* 3500'
Friday Morning* 3500'
Friday Afternoon* 4500'
Friday Evening* 4500'
Friday Night* 4000'
Saturday Morning 3500'
Saturday Afternoon 4000'
West Central Elevation
Thursday Evening* 3500'
Thursday Night* 3500'
Friday Morning* 4000'
Friday Afternoon* 5000'
Friday Evening* 4500'
Friday Night* 3500'
Saturday Morning 3500'
Saturday Afternoon 4000'
West South Elevation
Thursday Evening* 4000'
Thursday Night* 4000'
Friday Morning* 5000'
Friday Afternoon* 5500'
Friday Evening* 4500'
Friday Night* 3000'
Saturday Morning 3500'
Saturday Afternoon 4000'
Stevens Pass Elevation
Thursday Evening* 3000'
Thursday Night* 3000'
Friday Morning* 3500'
Friday Afternoon* 4500'
Friday Evening* 4500'
Friday Night* 3000'
Saturday Morning 3500'
Saturday Afternoon 4000'
Snoqualmie Pass Elevation
Thursday Evening* 3500'
Thursday Night* 3000'
Friday Morning* 4000'
Friday Afternoon* 5000'
Friday Evening* 4500'
Friday Night* 3500'
Saturday Morning 3500'
Saturday Afternoon 4000'
East North Elevation
Thursday Evening* 2000'
Thursday Night* 2500'
Friday Morning* 3000'
Friday Afternoon* 4500'
Friday Evening* 4500'
Friday Night* 2500'
Saturday Morning 3500'
Saturday Afternoon 4000'
East Central Elevation
Thursday Evening* 3000'
Thursday Night* 2500'
Friday Morning* 3000'
Friday Afternoon* 4500'
Friday Evening* 4500'
Friday Night* 3000'
Saturday Morning 3500'
Saturday Afternoon 4000'
East South Elevation
Thursday Evening* 3500'
Thursday Night* 3500'
Friday Morning* 4500'
Friday Afternoon* 5000'
Friday Evening* 4500'
Friday Night* 3500'
Saturday Morning 3500'
Saturday Afternoon 4000'
Mt. Hood Elevation
Thursday Evening* 6000'
Thursday Night* 8000'
Friday Morning* 8000'
Friday Afternoon* 6500'
Friday Evening* 5000'
Friday Night* 4500'
Saturday Morning 3500'
Saturday Afternoon 4000'

Issued: 2:21 PM PST Thursday, November 21, 2024

5000' Temperatures (°F)

Thursday Night Friday
Max / Min Max / Min
Olympics 29 / 23 36 / 29
West North 31 / 24 37 / 30
West Central 30 / 24 35 / 30
West South 32 / 26 35 / 32
Stevens Pass 29 / 25 35 / 29
Snoqualmie Pass 31 / 26 34 / 30
East North 27 / 24 32 / 27
East Central 29 / 25 35 / 30
East South 30 / 27 35 / 30
Mt. Hood 37 / 33 38 / 33
Olympics 5000' Temperature Forecast
(Max / Min)
Thursday Night 29 / 23
Friday 36 / 29
West North 5000' Temperature Forecast
(Max / Min)
Thursday Night 31 / 24
Friday 37 / 30
West Central 5000' Temperature Forecast
(Max / Min)
Thursday Night 30 / 24
Friday 35 / 30
West South 5000' Temperature Forecast
(Max / Min)
Thursday Night 32 / 26
Friday 35 / 32
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Thursday Night 29 / 25
Friday 35 / 29
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Thursday Night 31 / 26
Friday 34 / 30
East North 5000' Temperature Forecast
(Max / Min)
Thursday Night 27 / 24
Friday 32 / 27
East Central 5000' Temperature Forecast
(Max / Min)
Thursday Night 29 / 25
Friday 35 / 30
East South 5000' Temperature Forecast
(Max / Min)
Thursday Night 30 / 27
Friday 35 / 30
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Thursday Night 37 / 33
Friday 38 / 33

Issued: 2:21 PM PST Thursday, November 21, 2024

Ridgeline Winds (mph)

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

Issued: 2:21 PM PST Thursday, November 21, 2024

Extended Weather Synopsis

Similar weather from Saturday will extend to Sunday with some showers but not exceptionally stormy or wet weather.  A drying trend may try to take hold Monday or that may have to wait until the middle of next week. 

Extended Snow Level (ft)

Saturday Night Sunday * Sunday Night* Monday *
West North 2500' 3000' 1500' 2500'
Snoqualmie Pass 2500' 3500' 2500' 3000'
Mt. Hood 3500' 4000' 3500' 3500'
West North Elevation
Saturday Night 2500'
Sunday * 3000'
Sunday Night* 1500'
Monday * 2500'
Snoqualmie Pass Elevation
Saturday Night 2500'
Sunday * 3500'
Sunday Night* 2500'
Monday * 3000'
Mt. Hood Elevation
Saturday Night 3500'
Sunday * 4000'
Sunday Night* 3500'
Monday * 3500'

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

Previous forecast from Nov 20, 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’.