Issued: 1:59 PM PST Sunday, November 29, 2020
by Dennis D'Amico

Jump to: Weather Forecast I Snow/Freezing Level I Precipitation I Free Winds 5k I Free Winds 9k I Extended Weather

Weather Synopsis for Sunday night through Sunday

After a mostly sunny day that featured a wide variance in temperatures and freezing levels depending which side of the Cascade crest you were positioned, a powerful but quick moving frontal system is poised to deliver a decent shot of snow along with significant winds late tonight and Monday.  

The incoming Pacific frontal system now looks like it should sweep through the Cascades around 6 am on Monday morning. Snow levels will quickly drop with the onset of precipitation to 3000 ft or lower across the region. The front will bring a moderate shot of snow to the region with post-frontal snow showers helping to accumulate 6-12" across the west slopes of the Cascades, Mt. Hood and the Olympics and only slightly lower amounts along the east slopes of the Cascades through Monday afternoon. The highest snowfall totals will likely be from around Hwy 2 and north to Mt Baker along the west slopes of the Cascades.

This system will produce significant winds, both ahead of the front with strong to extreme southerlies developing for Hurricane Ridge and the Mt Baker area later tonight and behind the front with similar strength westerlies for most areas. Strong to locally extreme west winds during the day on Monday will buffet both west and east slopes of the Cascades.

A quickly building ridge offshore should start to shut down showers more quickly for the Mt Hood region and south Washington Cascades Monday afternoon and evening. The upper level ridge will quickly amplify over the area on Tuesday with a return to dry conditions. 

Weather Forecast

Hurricane Ridge
Sunday Night Mostly cloudy in the evening with moderate rain and snow developing after midnight. Strong to extreme ridgeline winds developing overnight.
Mt. Baker
Sunday Night Becoming mostly cloudy in the evening with rain and snow developing late tonight. Strong to extreme winds developing overnight.
Washington Pass and Leavenworth
Sunday Night Mostly clear becoming cloudy after midnight.
Stevens and Snoqualmie Pass
Sunday Night Becoming mostly cloudy in the evening with rain and snow developing late tonight. Moderate east winds in the Passes.
Mt. Rainier, Crystal and White Pass
Sunday Night Becoming mostly cloudy in the evening with rain and snow developing late tonight. Increasing ridgeline winds overnight.
Mt. Hood
Sunday Night Mostly clear becoming cloudy after midnight.

Snow/Freezing Level (ft)

Hurricane Ridge Mt. Baker Washington Pass Leavenworth Stevens Pass Snoqualmie Pass Mt. Rainier, Crystal & White Pass Mt. Hood
Sunday Evening Freezing Level * 6000' 5500' 3500' 3500' 4000' 5500' 6500' 6500'
Sunday Night Snow Level * 4500' 3000' 2000' 2500' 2500' 3000' 3500' 5500'
Monday Morning Snow Level 3000' 2500' 2000' 2000' 2500' 2500' 3000' 3000'
Monday Afternoon Snow Level 2000' 2000' 1500' 1500' 2000' 2000' 2000' 2500'
Monday Evening Snow Level 2000' 2000' 1000' 2000' 2000' 2000' 2000' 2500'
Monday Night Freezing Level 1000' 1000' 0' 1000' 1000' 1000' 1000' 1500'
Tuesday Morning Freezing Level 2000' 1500' 1500' 1500' 1500' 1500' 1500' 2000'
Hurricane Ridge Elevation
Sunday Evening Freezing Level
6000'
(Easterly Flow *)
Sunday Night Snow Level
4500'
(Easterly Flow *)
Monday Morning Snow Level
3000'
Monday Afternoon Snow Level
2000'
Monday Evening Snow Level
2000'
Monday Night Freezing Level
1000'
Tuesday Morning Freezing Level
2000'
Tuesday Afternoon Freezing Level
4500'
Mt. Baker Elevation
Sunday Evening Freezing Level
5500'
(Easterly Flow *)
Sunday Night Snow Level
3000'
(Easterly Flow *)
Monday Morning Snow Level
2500'
Monday Afternoon Snow Level
2000'
Monday Evening Snow Level
2000'
Monday Night Freezing Level
1000'
Tuesday Morning Freezing Level
1500'
Tuesday Afternoon Freezing Level
3500'
Washington Pass Elevation
Sunday Evening Freezing Level
3500'
(Easterly Flow *)
Sunday Night Snow Level
2000'
(Easterly Flow *)
Monday Morning Snow Level
2000'
Monday Afternoon Snow Level
1500'
Monday Evening Snow Level
1000'
Monday Night Freezing Level
0'
Tuesday Morning Freezing Level
1500'
Tuesday Afternoon Freezing Level
2500'
Leavenworth Elevation
Sunday Evening Freezing Level
3500'
(Easterly Flow *)
Sunday Night Snow Level
2500'
(Easterly Flow *)
Monday Morning Snow Level
2000'
Monday Afternoon Snow Level
1500'
Monday Evening Snow Level
2000'
Monday Night Freezing Level
1000'
Tuesday Morning Freezing Level
1500'
Tuesday Afternoon Freezing Level
3000'
Stevens Pass Elevation
Sunday Evening Freezing Level
4000'
(Easterly Flow *)
Sunday Night Snow Level
2500'
(Easterly Flow *)
Monday Morning Snow Level
2500'
Monday Afternoon Snow Level
2000'
Monday Evening Snow Level
2000'
Monday Night Freezing Level
1000'
Tuesday Morning Freezing Level
1500'
Tuesday Afternoon Freezing Level
3000'
Snoqualmie Pass Elevation
Sunday Evening Freezing Level
5500'
(Easterly Flow *)
Sunday Night Snow Level
3000'
(Easterly Flow *)
Monday Morning Snow Level
2500'
Monday Afternoon Snow Level
2000'
Monday Evening Snow Level
2000'
Monday Night Freezing Level
1000'
Tuesday Morning Freezing Level
1500'
Tuesday Afternoon Freezing Level
3000'
Mt. Rainier & Crystal Elevation
Sunday Evening Freezing Level
6500'
(Easterly Flow *)
Sunday Night Snow Level
3500'
(Easterly Flow *)
Monday Morning Snow Level
3000'
Monday Afternoon Snow Level
2000'
Monday Evening Snow Level
2000'
Monday Night Freezing Level
1000'
Tuesday Morning Freezing Level
1500'
Tuesday Afternoon Freezing Level
4000'
Mt. Hood Elevation
Sunday Evening Freezing Level
6500'
(Easterly Flow *)
Sunday Night Snow Level
5500'
(Easterly Flow *)
Monday Morning Snow Level
3000'
Monday Afternoon Snow Level
2500'
Monday Evening Snow Level
2500'
Monday Night Freezing Level
1500'
Tuesday Morning Freezing Level
2000'
Tuesday Afternoon Freezing Level
8000'

* Easterly flow in the Cascade Passes can cause locally lower Snow or Freezing levels than areas further west.
Freezing Level is when no precipitation is forecast.

Precipitation Forecast

Sunday Night Sunday Sunday Night Sunday
4 pm - 4 am 4 am - 4 pm 4 pm - 4 am 4 am - 4 pm
Hurricane Ridge 0.25 - 0.50 LT 0.25 0 0
Mt Baker Ski Area LT 0.25 0.75 -1.00 0 0
Washington Pass 0 0.25 - 0.50 0 0
Leavenworth 0 LT 0.25 0 0
Stevens Pass LT 0.10 0.75 LT 0.10 0
Snoqualmie Pass LT 0.10 0.50 - 0.75 LT 0.10 0
Mission Ridge 0 LT 0.25 0 0
Crystal Mt LT 0.10 0.50 0 0
Paradise LT 0.25 0.75 LT 0.10 0
White Pass 0 0.50 - 0.75 LT 0.10 0
Mt Hood Meadows 0 0.75 -1.00 LT 0.10 0
0 1.00 LT 0.10 0
Hurricane Ridge Precipitation Forecast
Sunday Night 0.25 - 0.50
Sunday LT 0.25
Sunday Night 0
Sunday 0
Mt Baker Ski Area Precipitation Forecast
Sunday Night LT 0.25
Sunday 0.75 -1.00
Sunday Night 0
Sunday 0
Washington Pass Precipitation Forecast
Sunday Night 0
Sunday 0.25 - 0.50
Sunday Night 0
Sunday 0
Leavenworth Precipitation Forecast
Sunday Night 0
Sunday LT 0.25
Sunday Night 0
Sunday 0
Stevens Pass Precipitation Forecast
Sunday Night LT 0.10
Sunday 0.75
Sunday Night LT 0.10
Sunday 0
Snoqualmie Pass Precipitation Forecast
Sunday Night LT 0.10
Sunday 0.50 - 0.75
Sunday Night LT 0.10
Sunday 0
Mission Ridge Precipitation Forecast
Sunday Night 0
Sunday LT 0.25
Sunday Night 0
Sunday 0
Crystal Mt Precipitation Forecast
Sunday Night LT 0.10
Sunday 0.50
Sunday Night 0
Sunday 0
Paradise Precipitation Forecast
Sunday Night LT 0.25
Sunday 0.75
Sunday Night LT 0.10
Sunday 0
White Pass Precipitation Forecast
Sunday Night 0
Sunday 0.50 - 0.75
Sunday Night LT 0.10
Sunday 0
Mt Hood Meadows Precipitation Forecast
Sunday Night 0
Sunday 0.75 -1.00
Sunday Night LT 0.10
Sunday 0
Timberline Precipitation Forecast
Sunday Night 0
Sunday 1.00
Sunday Night LT 0.10
Sunday 0

Free Winds at 5000' (mph)

Hurricane Ridge Mt. Baker Stevens to Snoqualmie Pass Mt. Rainier Mt. Hood
Sunday Evening S 20 - 30 S 20 - 30 ESE 15 - 25 S 10 - 20 SW 10 - 20
Sunday Night S 35 - 50 S 35 - 50 SE 15 - 25 S 20 - 30 SW 20 - 30
Monday Morning WSW 30 - 40 WSW 25 - 35 WSW 30 - 40 WSW 30 - 40 WSW 30 - 40
Hurricane Ridge Elevation
Sunday Evening S 20 - 30
Sunday Night S 35 - 50
Monday Morning WSW 30 - 40
Monday Afternoon W 25 - 35
Mt. Baker Elevation
Sunday Evening S 20 - 30
Sunday Night S 35 - 50
Monday Morning WSW 25 - 35
Monday Afternoon W 15 - 25
Stevens and Snoqualmie Pass Elevation
Sunday Evening ESE 15 - 25
Sunday Night SE 15 - 25
Monday Morning WSW 30 - 40
Monday Afternoon W 25 - 35
Mt. Rainier Elevation
Sunday Evening S 10 - 20
Sunday Night S 20 - 30
Monday Morning WSW 30 - 40
Monday Afternoon W 20 - 30
Mt. Hood Elevation
Sunday Evening SW 10 - 20
Sunday Night SW 20 - 30
Monday Morning WSW 30 - 40
Monday Afternoon W 25 - 35
Hurricane Ridge Direction - Speed
Sunday Evening S 20 - 30
Sunday Night S 35 - 50
Monday Morning WSW 30 - 40
Monday Afternoon W 25 - 35
Mt. Baker Direction - Speed
Sunday Evening S 20 - 30
Sunday Night S 35 - 50
Monday Morning WSW 25 - 35
Monday Afternoon W 15 - 25
Stevens and Snoqualmie Pass Direction - Speed
Sunday Evening ESE 15 - 25
Sunday Night SE 15 - 25
Monday Morning WSW 30 - 40
Monday Afternoon W 25 - 35
Mt. Rainier Direction - Speed
Sunday Evening S 10 - 20
Sunday Night S 20 - 30
Monday Morning WSW 30 - 40
Monday Afternoon W 20 - 30
Mt. Hood Direction - Speed
Sunday Evening SW 10 - 20
Sunday Night SW 20 - 30
Monday Morning WSW 30 - 40
Monday Afternoon W 25 - 35

Directions above indicate the direction the wind blows from on the 16-point cardinal scale. These winds indicate "free" winds, or those winds in the atmosphere not influenced by terrain. Topographical effects may produce greater or lower wind speeds in certain locations as well as significant variations in direction.

Free Winds at 9000' (mph)

Mt. Baker Washington Pass Stevens to Snoqualmie Pass Mt. Rainier Mt. Hood
Sunday Evening SW 35 - 45 SW 25 - 35 SW 20 - 30 SW 20 - 30 SW 20 - 30
Sunday Night SSW 50 - 60 SW 30 - 40 SW 40 - 60 SW 40 - 60 SW 45 - 60
Monday Morning SW 30 - 40 SW 35 - 45 WSW 50 - 60 W 50 - 60 W 55 - 65
Mt. Baker Direction - Speed
Sunday Evening SW 35 - 45
Sunday Night SSW 50 - 60
Monday Morning SW 30 - 40
Monday Afternoon W 30 - 40
Washington Pass Direction - Speed
Sunday Evening SW 25 - 35
Sunday Night SW 30 - 40
Monday Morning SW 35 - 45
Monday Afternoon W 40 - 50
Stevens and Snoqualmie Pass Direction - Speed
Sunday Evening SW 20 - 30
Sunday Night SW 40 - 60
Monday Morning WSW 50 - 60
Monday Afternoon WNW 40 - 50
Mt. Rainier Direction - Speed
Sunday Evening SW 20 - 30
Sunday Night SW 40 - 60
Monday Morning W 50 - 60
Monday Afternoon WNW 40 - 50
Mt. Hood Direction - Speed
Sunday Evening SW 20 - 30
Sunday Night SW 45 - 60
Monday Morning W 55 - 65
Monday Afternoon WNW 50 - 60

Extended Weather Synopsis for Sunday night through Sunday

In the extended, dry and mainly clear weather will take hold with the next weather system at least several days away.  A high amplitude ridge will flood the area with mild temperatures and high freezing levels; 10,000-11,000 ft by Wednesday. However, cold air will stay entrenched on the east side of the Cascades. As strong surface high pressure slides into the inland NW Tuesday night, offshore flow will drive that cold air through the Cascade Passes and likely up to Crest level as well. We should be in for an extended period of east winds as well as large temperature inversions, especially in the Cascade Passes and along the lower slopes on the east-side. 

Extended Snow/Freezing Levels

Mt. Baker Snoqualmie Pass Mt. Hood Easterly Flow *
Tuesday Night Freezing Level 8000' - 10000' 4000' - 6000' 8000' - 10000' *
Wednesday Freezing Level 10000' - 11000' 10000' - 11000' 10000' - 11000' *
Wednesday Night Freezing Level 10000' - 11000' 10000' - 11000' 10000' - 11000' *
Mt. Baker Elevation
Tuesday Night Freezing Level
8000' - 10000'
(Easterly Flow *)
Wednesday Freezing Level
10000' - 11000'
(Easterly Flow *)
Wednesday Night Freezing Level
10000' - 11000'
(Easterly Flow *)
Thursday Freezing Level
10000' - 11000'
(Easterly Flow *)
Snoqualmie Pass Elevation
Tuesday Night Freezing Level
4000' - 6000'
(Easterly Flow *)
Wednesday Freezing Level
10000' - 11000'
(Easterly Flow *)
Wednesday Night Freezing Level
10000' - 11000'
(Easterly Flow *)
Thursday Freezing Level
10000' - 11000'
(Easterly Flow *)
Mt. Hood Elevation
Tuesday Night Freezing Level
8000' - 10000'
(Easterly Flow *)
Wednesday Freezing Level
10000' - 11000'
(Easterly Flow *)
Wednesday Night Freezing Level
10000' - 11000'
(Easterly Flow *)
Thursday Freezing Level
10000' - 11000'
(Easterly Flow *)

* Easterly flow in the Cascade Passes can cause locally lower Snow or Freezing levels than areas further west.
Freezing Level is when no precipitation is forecast.

Jump to: Weather Forecast I Snow/Freezing Level I Precipitation I Free Winds 5k I Free Winds 9k I Extended Weather

Previous forecast from Nov 29, 2020

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