Issued: 1:57 PM PST Friday, December 30, 2016
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 Friday & Sunday

A quick moving frontal system in strong westerly flow produced about 10-12 inches of snow along the north and central Cascades of Washington Thursday night. Less snow was seen in the Olympics, the south Washington Cascades, Mt. Hood and below about 4000 feet for the central Cascades due to a period of rain Thursday evening.  

 A longwave trough axis oriented E-W over Washington Friday morning will slide south later this morning with weak ridging building into British Columbia. The PNW should see a drying trend with a healthy does of sunshine and steady cold temperatures expected this afternoon. 

A quick moving system upstream in NW flow will slide toward the area on Saturday, spreading light snowfall over the Olympics and north and central Cascades by early afternoon.  

A light to moderate shot of snowfall should come Saturday night as the front quickly sweeps south and a cold upper trough begins to dig off the Washington coast.

Weather Forecast

Olympics
Friday Afternoon - Friday Night

Mostly clear. 

Saturday Morning

Increasing clouds. 

Saturday Afternoon

Light snow developing by late morning with winds increasing. 

Washington Cascades near and west of the crest including Stevens, Snoqualmie, and White Passes
Friday Afternoon - Friday Night

Partly to mostly clear. Isolated light snow showers in the afternoon.  

Saturday Morning

Increasing clouds north part.  Mostly sunny south and central Washington Cascades. 

Saturday Afternoon

Light snow north and central Washington Cascades.  Becoming cloudy south Washington Cascades. Alpine winds increasing beginning mid-day. 

East slopes of the Washington Cascades
Friday Afternoon - Friday Night

Mostly clear.  

Saturday Morning

Increasing clouds north part.  Mostly sunny south and central Washington Cascades. 

Saturday Afternoon

Light snow developing north and central Washington Cascades. Becoming cloudy south Washington Cascades. Alpine winds increasing beginning mid-day. 

Mt. Hood Area
Friday Afternoon - Friday Night

Mostly clear. 

Saturday Morning - Saturday Mid-day

Mostly sunny. Milder. 

Saturday Afternoon

Becoming mostly cloudy with light snow developing late. Alpine winds increasing. 

Snow/Freezing Level (ft)

Hurricane Ridge Mt. Baker Washington Pass Leavenworth Stevens Pass Snoqualmie Pass Mt. Rainier, Crystal & White Pass Mt. Hood
Friday - Saturday Morning Snow Level 1500' 1500' 500' ' ' 1000' ' 2000'
Saturday Mid-day Snow Level 2500' 1000' 500' ' ' 1000' ' 6000'
Saturday Afternoon Snow Level 1500' 1000' 500' ' ' 1500' ' 1500'
Hurricane Ridge Elevation
Friday - Saturday Morning Snow Level
1500'
Saturday Mid-day Snow Level
2500'
Saturday Afternoon Snow Level
1500'
Saturday Night Snow Level
0'
Mt. Baker Elevation
Friday - Saturday Morning Snow Level
1500'
Saturday Mid-day Snow Level
1000'
Saturday Afternoon Snow Level
1000'
Saturday Night Snow Level
0'
Washington Pass Elevation
Friday - Saturday Morning Snow Level
500'
Saturday Mid-day Snow Level
500'
Saturday Afternoon Snow Level
500'
Saturday Night Snow Level
0'
Leavenworth Elevation
Friday - Saturday Morning Snow Level
'
Saturday Mid-day Snow Level
'
Saturday Afternoon Snow Level
'
Saturday Night Snow Level
'
Stevens Pass Elevation
Friday - Saturday Morning Snow Level
'
Saturday Mid-day Snow Level
'
Saturday Afternoon Snow Level
'
Saturday Night Snow Level
'
Snoqualmie Pass Elevation
Friday - Saturday Morning Snow Level
1000'
Saturday Mid-day Snow Level
1000'
Saturday Afternoon Snow Level
1500'
Saturday Night Snow Level
0'
Mt. Rainier & Crystal Elevation
Friday - Saturday Morning Snow Level
'
Saturday Mid-day Snow Level
'
Saturday Afternoon Snow Level
'
Saturday Night Snow Level
'
Mt. Hood Elevation
Friday - Saturday Morning Snow Level
2000'
Saturday Mid-day Snow Level
6000'
Saturday Afternoon Snow Level
1500'
Saturday Night Snow Level
1000'

* 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 Sunday
Hurricane Ridge LT 0.10 0.25 - 0.50
Mt Baker Ski Area LT 0.10 0.25 - 0.50
Washington Pass LT 0.10 LT 0.25
Stevens Pass LT 0.25 0.50 - 0.75
Snoqualmie Pass LT 0.25 0.50 - 0.75
Mission Ridge LT 0.10 LT 0.25
Crystal Mt LT 0.10 LT 0.25
Paradise LT 0.10 0 - 0.50
White Pass LT 0.10 0.25 - 0.50
Mt Hood Meadows LT 0.10 0 - 0.50
LT 0.10 0.50 - 0.75

Free Winds at 5000' (mph)

Hurricane Ridge Mt. Baker Stevens to Snoqualmie Pass Mt. Rainier Mt. Hood
Friday Afternoon - Friday Night N 0 - 10 NW 0 - 10 NW 0 - 10 --- - NW 0 - 10
Saturday Morning W 10 - 20 SW 5 - 15 SW 5 - 15 --- - W 5 - 15
Saturday Afternoon - Evening W 20 - 30 SW 5 - 15 WSW 15 - 30 --- - W 20 - 30
Hurricane Ridge Elevation
Friday Afternoon - Friday Night N 0 - 10
Saturday Morning W 10 - 20
Saturday Afternoon - Evening W 20 - 30
Saturday Night NE 10 - 20
Mt. Baker Elevation
Friday Afternoon - Friday Night NW 0 - 10
Saturday Morning SW 5 - 15
Saturday Afternoon - Evening SW 5 - 15
Saturday Night NE 10 - 20
Stevens and Snoqualmie Pass Elevation
Friday Afternoon - Friday Night NW 0 - 10
Saturday Morning SW 5 - 15
Saturday Afternoon - Evening WSW 15 - 30
Saturday Night NW 0 - 10
Mt. Rainier Elevation
Friday Afternoon - Friday Night --- -
Saturday Morning --- -
Saturday Afternoon - Evening --- -
Saturday Night --- -
Mt. Hood Elevation
Friday Afternoon - Friday Night NW 0 - 10
Saturday Morning W 5 - 15
Saturday Afternoon - Evening W 20 - 30
Saturday Night W 20 - 30
Hurricane Ridge Direction - Speed
Friday Afternoon - Friday Night N 0 - 10
Saturday Morning W 10 - 20
Saturday Afternoon - Evening W 20 - 30
Saturday Night NE 10 - 20
Mt. Baker Direction - Speed
Friday Afternoon - Friday Night NW 0 - 10
Saturday Morning SW 5 - 15
Saturday Afternoon - Evening SW 5 - 15
Saturday Night NE 10 - 20
Stevens and Snoqualmie Pass Direction - Speed
Friday Afternoon - Friday Night NW 0 - 10
Saturday Morning SW 5 - 15
Saturday Afternoon - Evening WSW 15 - 30
Saturday Night NW 0 - 10
Mt. Rainier Direction - Speed
Friday Afternoon - Friday Night --- -
Saturday Morning --- -
Saturday Afternoon - Evening --- -
Saturday Night --- -
Mt. Hood Direction - Speed
Friday Afternoon - Friday Night NW 0 - 10
Saturday Morning W 5 - 15
Saturday Afternoon - Evening W 20 - 30
Saturday Night W 20 - 30

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
Friday Afternoon N 10 - 20 N 15 - 25 N 10 - 20 --- - NNE 10 - 20
Friday Night - Saturday Morning NW 15 - 25 NW 15 - 30 NW 15 - 25 --- - NE 15 - 25
Saturday Mid-day - Saturday Afternoon W 25 - 35 W 35 - 45 W 35 - 50 --- - WNW 25 - 40
Mt. Baker Direction - Speed
Friday Afternoon N 10 - 20
Friday Night - Saturday Morning NW 15 - 25
Saturday Mid-day - Saturday Afternoon W 25 - 35
Saturday Night NE 20 - 30
Washington Pass Direction - Speed
Friday Afternoon N 15 - 25
Friday Night - Saturday Morning NW 15 - 30
Saturday Mid-day - Saturday Afternoon W 35 - 45
Saturday Night NE 15 - 25
Stevens and Snoqualmie Pass Direction - Speed
Friday Afternoon N 10 - 20
Friday Night - Saturday Morning NW 15 - 25
Saturday Mid-day - Saturday Afternoon W 35 - 50
Saturday Night NW 15 - 30
Mt. Rainier Direction - Speed
Friday Afternoon --- -
Friday Night - Saturday Morning --- -
Saturday Mid-day - Saturday Afternoon --- -
Saturday Night --- -
Mt. Hood Direction - Speed
Friday Afternoon NNE 10 - 20
Friday Night - Saturday Morning NE 15 - 25
Saturday Mid-day - Saturday Afternoon WNW 25 - 40
Saturday Night WNW 35 - 50

Extended Weather Synopsis for Sunday night through Sunday

The cold upper level trough will slowly dig off the Oregon/California coast through Tuesday. A clearing trend should begin on Sunday from north to south as drier air works into the region.  Areas closer to the upper trough like the south Washington Cascades and Mt. Hood will see more cloud cover and snow showers through Sunday. 

The upper level pattern combined with strong high pressure sliding south along the Canadian Rockies will drive arctic air into the PNW including the west slopes and Olympics. The coldest air begins filtering into the north Cascades and Olympics Sunday afternoon and is firmly entrenched throughout the PNW by Monday morning. Moderate NE alpine winds for the far north Cascades on Sunday will shift to the central and south Cascades on Monday with to moderate to strong easterly winds. Brrr.

Extended Weather

Olympics, Washington Cascades and Mt. Hood
Sunday - Sunday Night

Clearing north and central west Cascades.  Mostly cloudy with scattered light snow showers Olympics, east slopes of the Cascades. Cloudy with light snow showers Mt. Hood.  Moderate NE alpine wind far north Cascades.  

Monday - Monday Night

Very cold. Mostly clear west slopes and Olympics.  Mostly cloudy east slopes and Mt. Hood with scattered light snow showers. Moderate E winds central and south Washington Cascades and Mt. Hood. 

Tuesday

Very cold and mostly sunny. 

Extended Snow/Freezing Levels

Mt. Baker Snoqualmie Pass Mt. Hood Easterly Flow *
Sunday - Monday Morning Snow Level 0' - 0' 0' - 0' 0' - 0'
Mt. Baker Elevation
Sunday - Monday Morning Snow Level
0' - 0'
Monday Afternoon - Tuesday Freezing Level
0' - 0'
(Easterly Flow *)
Snoqualmie Pass Elevation
Sunday - Monday Morning Snow Level
0' - 0'
Monday Afternoon - Tuesday Freezing Level
0' - 0'
(Easterly Flow *)
Mt. Hood Elevation
Sunday - Monday Morning Snow Level
0' - 0'
Monday Afternoon - Tuesday Freezing Level
0' - 0'
(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 Dec 30, 2016

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