Issued: 2:01 PM PST Monday, December 14, 2020
by Dennis D'Amico

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

Weather Synopsis

Scattered showers are still around this afternoon and on the light side except for a Puget Sound Convergence Zone that has lifted north toward the Mt Loop Hwy.  Showers will continue to taper down this evening but the next Pacific frontal system is already on our doorstep. The front should push through the Cascades mid-late morning on Tuesday, with precipitation starting before daybreak for most areas. While there is a moderate amount of precipitation with this system, post-frontal showers mid-day and early afternoon will help pad precipitation totals. Easterly flow ahead of the front will help keep snow levels around 3000' through the morning, but look for a pop to 4000' by mid-day at Stevens, Snoqualmie and White Passes following the passage of the front. West post-frontal winds will be strong as well. 

Showers will continue into Tuesday night before tapering back Wednesday morning.  We have entered a progressive weather pattern with weather systems arriving every day or so. The next system should spread precipitation over the region by late in the day on Wednesday.  There should be a bump in snow levels with the onset of heavier precipitation in the south Washington Cascades and Mt Hood area on Wednesday afternoon. 

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
Monday Night Cloudy with rain and snow developing after midnight, becoming moderate late.
Tuesday Moderate rain and snow becoming mostly cloudy with scattered light to moderate showers by mid morning.
Monday Night Cloudy with rain and snow developing after midnight, becoming moderate late.
Tuesday Moderate rain and snow becoming moderate showers late morning.
Monday Night Cloudy with light rain and snow developing after midnight.
Tuesday Moderate rain and snow becoming moderate showers late morning.
Monday Night Cloudy with rain and snow developing late.
Tuesday Moderate rain and snow becoming light to moderate showers late morning.
Monday Night Cloudy with rain and snow developing late. Light to moderate east winds at Pass level.
Tuesday Moderate rain and snow becoming light to moderate showers late morning. Light east winds becoming strong west winds at Pass level.
Monday Night Cloudy with rain and snow developing late. Light to moderate east winds at Pass level.
Tuesday Moderate rain and snow becoming light to moderate showers late morning. Light east winds becoming strong west winds at Pass level.
Monday Night Cloudy with rain and snow developing late.
Tuesday Moderate snow becoming light to occasionally moderate showers late morning.
Monday Night Cloudy.
Tuesday Moderate snow becoming light to occasionally moderate showers late morning.
Monday Night Cloudy.
Tuesday Moderate snow becoming light to occasionally moderate showers late morning.
Monday Night Cloudy.
Tuesday Moderate rain and snow becoming light to moderate showers late morning.

Issued: 2:01 PM PST Monday, December 14, 2020

Precipitation (in)

Monday Night Tuesday Tuesday Night Wednesday
4 pm - 4 am 4 am - 4 pm 4 pm - 4 am 4 am - 4 pm
Hurricane Ridge 0.25 0.25 - 0.50 LT 0.10 0.25 - 0.50
Mt Baker Ski Area 0.25 - 0.50 1.00 0.25 0.50
Mt. Loop - Barlow Pass LT 0.25 0.50 - 0.75 LT 0.25 0.25
Stevens Pass LT 0.10 0.75 0.25 0.25
Snoqualmie Pass LT 0.10 0.75 -1.00 0.25 0.25
Crystal Mt LT 0.10 0.50 LT 0.10 0.25
Paradise LT 0.10 1.00 0.25 0.25 - 0.50
White Pass LT 0.10 0.50 - 0.75 LT 0.25 LT 0.25
Washington Pass LT 0.10 0.50 LT 0.10 LT 0.25
Mission Ridge 0 0.25 0 LT 0.25
Salmon la Sac - Gallagher Head 0 0.50 LT 0.10 0.25 - 0.50
Tieton River - Darland Mt. 0 0.25 - 0.50 0 0.25
Mt Hood Meadows 0 0.50 - 0.75 LT 0.25 0.25 - 0.50
Timberline 0 0.75 LT 0.25 0.50
Hurricane Ridge Precipitation (in)
Monday Night 0.25
Tuesday 0.25 - 0.50
Tuesday Night LT 0.10
Wednesday 0.25 - 0.50
Mt Baker Ski Area Precipitation (in)
Monday Night 0.25 - 0.50
Tuesday 1.00
Tuesday Night 0.25
Wednesday 0.50
Mt. Loop - Barlow Pass Precipitation (in)
Monday Night LT 0.25
Tuesday 0.50 - 0.75
Tuesday Night LT 0.25
Wednesday 0.25
Stevens Pass Precipitation (in)
Monday Night LT 0.10
Tuesday 0.75
Tuesday Night 0.25
Wednesday 0.25
Snoqualmie Pass Precipitation (in)
Monday Night LT 0.10
Tuesday 0.75 -1.00
Tuesday Night 0.25
Wednesday 0.25
Crystal Mt Precipitation (in)
Monday Night LT 0.10
Tuesday 0.50
Tuesday Night LT 0.10
Wednesday 0.25
Paradise Precipitation (in)
Monday Night LT 0.10
Tuesday 1.00
Tuesday Night 0.25
Wednesday 0.25 - 0.50
White Pass Precipitation (in)
Monday Night LT 0.10
Tuesday 0.50 - 0.75
Tuesday Night LT 0.25
Wednesday LT 0.25
Washington Pass Precipitation (in)
Monday Night LT 0.10
Tuesday 0.50
Tuesday Night LT 0.10
Wednesday LT 0.25
Mission Ridge Precipitation (in)
Monday Night 0
Tuesday 0.25
Tuesday Night 0
Wednesday LT 0.25
Salmon la Sac - Gallagher Head Precipitation (in)
Monday Night 0
Tuesday 0.50
Tuesday Night LT 0.10
Wednesday 0.25 - 0.50
Tieton River - Darland Mt. Precipitation (in)
Monday Night 0
Tuesday 0.25 - 0.50
Tuesday Night 0
Wednesday 0.25
Mt Hood Meadows Precipitation (in)
Monday Night 0
Tuesday 0.50 - 0.75
Tuesday Night LT 0.25
Wednesday 0.25 - 0.50
Timberline Precipitation (in)
Monday Night 0
Tuesday 0.75
Tuesday Night LT 0.25
Wednesday 0.50

Issued: 2:01 PM PST Monday, December 14, 2020

Snow Level (ft)

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

Issued: 2:01 PM PST Monday, December 14, 2020

5000' Temperatures (°F)

Monday Night Tuesday
Max / Min Max / Min
Olympics 27 / 23 30 / 27
West North 25 / 24 28 / 25
West Central 25 / 23 29 / 25
West South 28 / 22 31 / 28
Stevens Pass 23 / 20 30 / 23
Snoqualmie Pass 24 / 21 30 / 24
East North 22 / 19 29 / 19
East Central 23 / 21 30 / 22
East South 24 / 20 31 / 24
Mt. Hood 26 / 22 33 / 28
Olympics 5000' Temperature Forecast
(Max / Min)
Monday Night 27 / 23
Tuesday 30 / 27
West North 5000' Temperature Forecast
(Max / Min)
Monday Night 25 / 24
Tuesday 28 / 25
West Central 5000' Temperature Forecast
(Max / Min)
Monday Night 25 / 23
Tuesday 29 / 25
West South 5000' Temperature Forecast
(Max / Min)
Monday Night 28 / 22
Tuesday 31 / 28
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Monday Night 23 / 20
Tuesday 30 / 23
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Monday Night 24 / 21
Tuesday 30 / 24
East North 5000' Temperature Forecast
(Max / Min)
Monday Night 22 / 19
Tuesday 29 / 19
East Central 5000' Temperature Forecast
(Max / Min)
Monday Night 23 / 21
Tuesday 30 / 22
East South 5000' Temperature Forecast
(Max / Min)
Monday Night 24 / 20
Tuesday 31 / 24
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Monday Night 26 / 22
Tuesday 33 / 28

Issued: 2:01 PM PST Monday, December 14, 2020

Ridgeline Winds (mph)

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

Issued: 2:01 PM PST Monday, December 14, 2020

Extended Weather Synopsis

The active weather pattern continues...until early next week.  Look for a dirty ridge to allow plenty of moisture over the northern half of the forecast area on Thursday and the next Pacific frontal system to arrive on Friday. This system has the potential to bring heavy precipitation through Saturday.  The snow level will bump around 2500-4500 in the extended. 

Extended Snow Level (ft)

Wednesday Night* Thursday Thursday Night Friday
West North 3000' 3000' 2000' 2500'
Snoqualmie Pass 3000' 3500' 2500' 3500'
Mt. Hood 3500' 3500' 2500' 4500'
West North Elevation
Wednesday Night* 3000'
Thursday 3000'
Thursday Night 2000'
Friday 2500'
Snoqualmie Pass Elevation
Wednesday Night* 3000'
Thursday 3500'
Thursday Night 2500'
Friday 3500'
Mt. Hood Elevation
Wednesday Night* 3500'
Thursday 3500'
Thursday Night 2500'
Friday 4500'

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

Previous forecast from Dec 14, 2020

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’.