Issued: 7:23 AM PST Sunday, December 17, 2017
by Dennis D'Amico

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

Weather Synopsis for Sunday & Saturday

The upper ridge that led to a long period of dry weather over the Pacific Northwest has been temporarily flattened as the polar jet takes aim at southern British Columbia through the short term.  This will open the door to warm frontal moisture in strong westerly flow aloft.  Moderate to locally heavy precipitation should affect the west slopes of the Olympics and central and northern Washington Cascades, with precipitation amounts falling off sharply to the south and east today. A warming trend will eventually overwhelm weak easterly flow in the Cascade Passes; Snoqualmie is expected to change to rain by mid-day while Stevens Pass should hold off until mid-late afternoon.   

The frontal boundary will finally shift south Sunday night through Monday morning, bringing some more moderate precipitation to the SW Cascades including the Paradise area. Crystal mountain looks to be fairly blocked in this pattern with much lower totals.  A slight cooling trend will take place late Sunday night through Monday, but snow levels for the southern Washington Cascades and Mt. Hood area should stay on the mild side throughout the short term. The other main weather factor will be strong W-SW winds which are expected to increase Sunday afternoon and stay strong through Monday morning.  

Precipitation should temporarily ease off Monday afternoon before another potent storm system approaching in westerly flow begins to renew moderate precipitation Monday night.  

Weather Forecast

Olympics
Sunday Light to moderate rain and snow. Mild.
Sunday Night Light to moderate rain and snow. Cooling trend late.
Monday Light rain and snow. Cooler.
Washington Cascades near and west of the Crest including Stevens, Snoqualmie and White Passes
Sunday Light rain and snow developing in the morning and increasing during the afternoon, becoming moderate to heavy central Cascades. Warming trend.
Sunday Night Light to moderate rain and snow, locally heavier Stevens and Snoqualmie Passes. Milder. Windy.
Monday Moderate rain and snow becoming light in the afternoon. Slow cooling trend.
East Slopes of the Washington Cascades
Sunday Light rain and snow developing in the morning and increasing during the afternoon, becoming moderate central-east Cascades near the Cascade crest. Slow warming trend.
Sunday Night Light rain and snow, locally moderate central-east Cascades near the Cascade crest. Milder. Windy.
Monday Light to occasionally moderate rain and snow tapering off in the afternoon. Slow cooling trend.
Mt. Hood
Sunday Periods of light rain and snow. Mild.
Sunday Night Periods of light rain and snow. Mild.
Monday Light to occasionally moderate rain and snow.

Snow/Freezing Level (ft)

Hurricane Ridge Mt. Baker Washington Pass Leavenworth Stevens Pass Snoqualmie Pass Mt. Rainier, Crystal & White Pass Mt. Hood
Sunday Morning Snow Level * 6500' 3000' 2500' ' ' 3500' ' 6500'
Sunday Mid-day Snow Level * 6500' 4000' 3500' ' ' 4000' ' 7000'
Sunday Night Snow Level 6000' 4500' 4500' ' ' 5500' ' 6000'
Monday Morning Snow Level 4500' 3500' 4000' ' ' 5000' ' 6000'
Monday Afternoon Snow Level 3000' 2500' 2500' ' ' 3500' ' 6000'
Monday Night Snow Level * 3500' 2500' 3000' ' ' 4500' ' 5500'
Hurricane Ridge Elevation
Sunday Morning Snow Level
6500'
(Easterly Flow *)
Sunday Mid-day Snow Level
6500'
(Easterly Flow *)
Sunday Night Snow Level
6000'
Monday Morning Snow Level
4500'
Monday Afternoon Snow Level
3000'
Monday Night Snow Level
3500'
(Easterly Flow *)
Sunday Afternoon Snow Level
6500'
Mt. Baker Elevation
Sunday Morning Snow Level
3000'
(Easterly Flow *)
Sunday Mid-day Snow Level
4000'
(Easterly Flow *)
Sunday Night Snow Level
4500'
Monday Morning Snow Level
3500'
Monday Afternoon Snow Level
2500'
Monday Night Snow Level
2500'
(Easterly Flow *)
Sunday Afternoon Snow Level
4500'
Washington Pass Elevation
Sunday Morning Snow Level
2500'
(Easterly Flow *)
Sunday Mid-day Snow Level
3500'
(Easterly Flow *)
Sunday Night Snow Level
4500'
Monday Morning Snow Level
4000'
Monday Afternoon Snow Level
2500'
Monday Night Snow Level
3000'
(Easterly Flow *)
Sunday Afternoon Snow Level
4000'
Leavenworth Elevation
Sunday Morning Snow Level
'
(Easterly Flow *)
Sunday Mid-day Snow Level
'
(Easterly Flow *)
Sunday Night Snow Level
'
Monday Morning Snow Level
'
Monday Afternoon Snow Level
'
Monday Night Snow Level
'
(Easterly Flow *)
Sunday Afternoon Snow Level
'
Stevens Pass Elevation
Sunday Morning Snow Level
'
(Easterly Flow *)
Sunday Mid-day Snow Level
'
(Easterly Flow *)
Sunday Night Snow Level
'
Monday Morning Snow Level
'
Monday Afternoon Snow Level
'
Monday Night Snow Level
'
(Easterly Flow *)
Sunday Afternoon Snow Level
'
Snoqualmie Pass Elevation
Sunday Morning Snow Level
3500'
(Easterly Flow *)
Sunday Mid-day Snow Level
4000'
(Easterly Flow *)
Sunday Night Snow Level
5500'
Monday Morning Snow Level
5000'
Monday Afternoon Snow Level
3500'
Monday Night Snow Level
4500'
(Easterly Flow *)
Sunday Afternoon Snow Level
5500'
Mt. Rainier & Crystal Elevation
Sunday Morning Snow Level
'
(Easterly Flow *)
Sunday Mid-day Snow Level
'
(Easterly Flow *)
Sunday Night Snow Level
'
Monday Morning Snow Level
'
Monday Afternoon Snow Level
'
Monday Night Snow Level
'
(Easterly Flow *)
Sunday Afternoon Snow Level
'
Mt. Hood Elevation
Sunday Morning Snow Level
6500'
(Easterly Flow *)
Sunday Mid-day Snow Level
7000'
(Easterly Flow *)
Sunday Night Snow Level
6000'
Monday Morning Snow Level
6000'
Monday Afternoon Snow Level
6000'
Monday Night Snow Level
5500'
(Easterly Flow *)
Sunday Afternoon Snow Level
7000'

* 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

Saturday Saturday
Hurricane Ridge 0.50 - 0.75 0 - 0.75
Mt Baker Ski Area 0 - 1.50 0 - 0.75
Washington Pass 0 - 0.75 0.50 - 0.75
Stevens Pass 2.00 - 2.50 1.00 - 1.50
Snoqualmie Pass 2.00 - 3.00 0 - 1.50
Mission Ridge 0.25 - 0.50 0.25 - 0.50
Crystal Mt 0.25 - 0.50 0 - 0.75
Paradise 1.00 - 1.50 0 - 2.00
White Pass 0.25 - 0.50 0 - 1.00
Mt Hood Meadows LT 0.25 0 - 0.50
LT 0.25 0 - 0.75

Free Winds at 5000' (mph)

Hurricane Ridge Mt. Baker Stevens to Snoqualmie Pass Mt. Rainier Mt. Hood
Sunday Morning SW 10 - 20 SW 5 - 15 WSW 10 - 20 --- - W 5 - 15
Sunday Afternoon WSW 20 - 30 SW 15 - 25 SW 25 - 40 --- - W 10 - 20
Sunday Night WSW 20 - 30 WSW 20 - 30 SW 30 - 50 --- - SW 20 - 30
Monday Morning WSW 15 - 25 WSW 15 - 25 WSW 15 - 30 --- - WSW 25 - 35
Monday Afternoon W 5 - 15 WSW 5 - 15 WSW 10 - 20 --- - SW 20 - 30
Hurricane Ridge Elevation
Sunday Morning SW 10 - 20
Sunday Afternoon WSW 20 - 30
Sunday Night WSW 20 - 30
Monday Morning WSW 15 - 25
Monday Afternoon W 5 - 15
Monday Night S 15 - 25
Mt. Baker Elevation
Sunday Morning SW 5 - 15
Sunday Afternoon SW 15 - 25
Sunday Night WSW 20 - 30
Monday Morning WSW 15 - 25
Monday Afternoon WSW 5 - 15
Monday Night SE 5 - 15
Stevens and Snoqualmie Pass Elevation
Sunday Morning WSW 10 - 20
Sunday Afternoon SW 25 - 40
Sunday Night SW 30 - 50
Monday Morning WSW 15 - 30
Monday Afternoon WSW 10 - 20
Monday Night SW 20 - 30
Mt. Rainier Elevation
Sunday Morning --- -
Sunday Afternoon --- -
Sunday Night --- -
Monday Morning --- -
Monday Afternoon --- -
Monday Night --- -
Mt. Hood Elevation
Sunday Morning W 5 - 15
Sunday Afternoon W 10 - 20
Sunday Night SW 20 - 30
Monday Morning WSW 25 - 35
Monday Afternoon SW 20 - 30
Monday Night SW 25 - 35
Hurricane Ridge Direction - Speed
Sunday Morning SW 10 - 20
Sunday Afternoon WSW 20 - 30
Sunday Night WSW 20 - 30
Monday Morning WSW 15 - 25
Monday Afternoon W 5 - 15
Monday Night S 15 - 25
Mt. Baker Direction - Speed
Sunday Morning SW 5 - 15
Sunday Afternoon SW 15 - 25
Sunday Night WSW 20 - 30
Monday Morning WSW 15 - 25
Monday Afternoon WSW 5 - 15
Monday Night SE 5 - 15
Stevens and Snoqualmie Pass Direction - Speed
Sunday Morning WSW 10 - 20
Sunday Afternoon SW 25 - 40
Sunday Night SW 30 - 50
Monday Morning WSW 15 - 30
Monday Afternoon WSW 10 - 20
Monday Night SW 20 - 30
Mt. Rainier Direction - Speed
Sunday Morning --- -
Sunday Afternoon --- -
Sunday Night --- -
Monday Morning --- -
Monday Afternoon --- -
Monday Night --- -
Mt. Hood Direction - Speed
Sunday Morning W 5 - 15
Sunday Afternoon W 10 - 20
Sunday Night SW 20 - 30
Monday Morning WSW 25 - 35
Monday Afternoon SW 20 - 30
Monday Night SW 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 Morning W 30 - 40 W 30 - 40 W 30 - 40 --- - NW 25 - 35
Sunday Afternoon WSW 35 - 45 WSW 40 - 50 W 40 - 50 --- - W 45 - 55
Sunday Night WSW 40 - 50 W 50 - 60 WSW 45 - 60 --- - W 45 - 55
Monday Morning WSW 30 - 40 W 45 - 55 W 45 - 60 --- - W 45 - 55
Monday Afternoon WSW 25 - 35 W 35 - 45 WSW 45 - 55 --- - W 35 - 45
Mt. Baker Direction - Speed
Sunday Morning W 30 - 40
Sunday Afternoon WSW 35 - 45
Sunday Night WSW 40 - 50
Monday Morning WSW 30 - 40
Monday Afternoon WSW 25 - 35
Monday Night SW 25 - 35
Washington Pass Direction - Speed
Sunday Morning W 30 - 40
Sunday Afternoon WSW 40 - 50
Sunday Night W 50 - 60
Monday Morning W 45 - 55
Monday Afternoon W 35 - 45
Monday Night SW 25 - 35
Stevens and Snoqualmie Pass Direction - Speed
Sunday Morning W 30 - 40
Sunday Afternoon W 40 - 50
Sunday Night WSW 45 - 60
Monday Morning W 45 - 60
Monday Afternoon WSW 45 - 55
Monday Night SW 40 - 50
Mt. Rainier Direction - Speed
Sunday Morning --- -
Sunday Afternoon --- -
Sunday Night --- -
Monday Morning --- -
Monday Afternoon --- -
Monday Night --- -
Mt. Hood Direction - Speed
Sunday Morning NW 25 - 35
Sunday Afternoon W 45 - 55
Sunday Night W 45 - 55
Monday Morning W 45 - 55
Monday Afternoon W 35 - 45
Monday Night SW 40 - 50

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.

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

Previous forecast from Dec 16, 2017

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