Issued: 1:55 PM PDT Friday, April 10, 2015
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 & Friday

Winter is coming... back to the PNW this weekend after a day of increasing mid and high level clouds across the region Friday. An initial and weak frontal boundary around 130W this morning has been absorbed by the main incoming Pacific frontal system driven by a rare sight this season; a consolidated westerly jet that will take aim at the WA/OR border through early Saturday morning.  

Precipitation will increase over the Olympics this afternoon and elsewhere later this evening. Behind the front sharp cooling and favorable orographic westerly flow is expected for the Cascade west slopes Saturday and Saturday evening. The upper level trough axis should enhance shower coverage and intensity Saturday afternoon.

A Puget Sound convergence zone should form tomorrow with significant local accumulations possible between Stevens and Snoqualmie Passes through late Saturday night. There is increasing forecast confidence the convergence zone will set up shop predominately in the Stevens Pass vicinity. The air mass is marginally unstable Saturday... and embedded thunderstorms may develop with the showery pattern especially in the convergence zone and the northwest Cascades.   

Weather Forecast

Olympics, Washington Cascades near and west of the crest and Mt. Hood area
Friday Afternoon

Increasing mid and high clouds with light rain and snow developing north Cascades and Olympics. 
Friday Night

Light to moderate rain and snow becoming showers overnight.  Precipitation potentially heavy Mt. Baker area Friday evening. Sharp cooling trend late Friday night. Windy.  
Saturday Morning

Mostly cloudy with light to occasionally moderate rain and snow showers. Moderate west winds. 
Saturday Afternoon - Saturday Night

Mostly cloudy with light to moderate rain and snow showers. Chance of thunderstorms. Showers may be locally heavy near a Puget Sound Convergnce zone near Stevens and Snoqualmie Passes. Moderate west winds. Showers easing late Saturday night. 
East slopes of the Washington Cascades
Friday Afternoon

Increasing mid and high clouds with occasional light rain and snow developing late afternoon northeast Cascades. 
Friday Night

Light to occasionally moderate rain and snow becoming showers overnight. Sharp cooling trend late Friday night. Windy.  
Saturday Morning

Mostly cloudy with light rain and snow showers. Moderate west winds. 
Saturday Afternoon - Saturday Night

Mostly cloudy with light rain and snow showers, occasionally moderate near the Cascade crest. Moderate west winds. Showers tapering off late Saturday night. 

Issued: 1:55 PM PDT Friday, April 10, 2015

Snow/Freezing Level (ft)

Hurricane Ridge Mt. Baker Washington Pass Leavenworth Stevens Pass Snoqualmie Pass Mt. Rainier, Crystal & White Pass Mt. Hood
Friday Afternoon Snow Level 4500' 4500' 5000' ' ' 5000' ' 5500'
Friday Evening Snow Level 3000' 4000' 4500' ' ' 4000' ' 4500'
Friday Night Snow Level 2000' 2000' 2500' ' ' 2500' ' 3500'
Saturday Snow Level 3000' 2500' 2500' ' ' 3000' ' 3500'
Saturday Night Snow Level 1500' 1500' 1500' ' ' 1500' ' 2500'
Hurricane Ridge Elevation
Friday Afternoon Snow Level
4500'
Friday Evening Snow Level
3000'
Friday Night Snow Level
2000'
Saturday Snow Level
3000'
Saturday Night Snow Level
1500'
Mt. Baker Elevation
Friday Afternoon Snow Level
4500'
Friday Evening Snow Level
4000'
Friday Night Snow Level
2000'
Saturday Snow Level
2500'
Saturday Night Snow Level
1500'
Washington Pass Elevation
Friday Afternoon Snow Level
5000'
Friday Evening Snow Level
4500'
Friday Night Snow Level
2500'
Saturday Snow Level
2500'
Saturday Night Snow Level
1500'
Leavenworth Elevation
Friday Afternoon Snow Level
'
Friday Evening Snow Level
'
Friday Night Snow Level
'
Saturday Snow Level
'
Saturday Night Snow Level
'
Stevens Pass Elevation
Friday Afternoon Snow Level
'
Friday Evening Snow Level
'
Friday Night Snow Level
'
Saturday Snow Level
'
Saturday Night Snow Level
'
Snoqualmie Pass Elevation
Friday Afternoon Snow Level
5000'
Friday Evening Snow Level
4000'
Friday Night Snow Level
2500'
Saturday Snow Level
3000'
Saturday Night Snow Level
1500'
Mt. Rainier & Crystal Elevation
Friday Afternoon Snow Level
'
Friday Evening Snow Level
'
Friday Night Snow Level
'
Saturday Snow Level
'
Saturday Night Snow Level
'
Mt. Hood Elevation
Friday Afternoon Snow Level
5500'
Friday Evening Snow Level
4500'
Friday Night Snow Level
3500'
Saturday Snow Level
3500'
Saturday Night Snow Level
2500'

* 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

Friday Friday
Hurricane Ridge 0 - 0.50 0.25 - 0.50
Mt Baker Ski Area 1.00 - 1.50 0.50 - 0.75
Washington Pass 0 - 0.50 LT 0.25
Stevens Pass 0 - 0.50 1.00 - 1.50
Snoqualmie Pass 0 - 0.75 0.50 - 0.75
Mission Ridge LT 0.10 LT 0.25
Crystal Mt 0.25 - 0.50 LT 0.25
Paradise 0.75 - 1.00 0.75 - 1.00
White Pass 0.50 - 0.75 0 - 0.50
Mt Hood Meadows 0 - 0.75 0.25 - 0.50
Timberline 0 - 1.00 0.50 - 0.75

LT = less than; WE or Water equivalent is the liquid water equivalent of melted snow in hundredths of inches. As a rough approximation 1 inch of snow = about .10 inches WE, or 10 inches of snow = about 1 inch WE.

Issued: 1:55 PM PDT Friday, April 10, 2015

Free Winds at 5000' (mph)

Hurricane Ridge Mt. Baker Stevens to Snoqualmie Pass Mt. Rainier Mt. Hood
Friday Afternoon SW 25 - 35 SSW 25 - 35 SW 15 - 25 --- - SW 20 - 30
Friday Night SW 20 - 30 SW 20 - 30 SW 25 - 35 --- - SW 30 - 40
Saturday - Saturday Night W 15 - 25 WSW 15 - 25 WSW 15 - 30 --- - W 20 - 30
Hurricane Ridge Elevation
Friday Afternoon SW 25 - 35
Friday Night SW 20 - 30
Saturday - Saturday Night W 15 - 25
Mt. Baker Elevation
Friday Afternoon SSW 25 - 35
Friday Night SW 20 - 30
Saturday - Saturday Night WSW 15 - 25
Stevens and Snoqualmie Pass Elevation
Friday Afternoon SW 15 - 25
Friday Night SW 25 - 35
Saturday - Saturday Night WSW 15 - 30
Mt. Rainier Elevation
Friday Afternoon --- -
Friday Night --- -
Saturday - Saturday Night --- -
Mt. Hood Elevation
Friday Afternoon SW 20 - 30
Friday Night SW 30 - 40
Saturday - Saturday Night W 20 - 30
Hurricane Ridge Direction - Speed
Friday Afternoon SW 25 - 35
Friday Night SW 20 - 30
Saturday - Saturday Night W 15 - 25
Mt. Baker Direction - Speed
Friday Afternoon SSW 25 - 35
Friday Night SW 20 - 30
Saturday - Saturday Night WSW 15 - 25
Stevens and Snoqualmie Pass Direction - Speed
Friday Afternoon SW 15 - 25
Friday Night SW 25 - 35
Saturday - Saturday Night WSW 15 - 30
Mt. Rainier Direction - Speed
Friday Afternoon --- -
Friday Night --- -
Saturday - Saturday Night --- -
Mt. Hood Direction - Speed
Friday Afternoon SW 20 - 30
Friday Night SW 30 - 40
Saturday - 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 SW 30 - 40 SW 15 - 25 SW 30 - 40 --- - SW 30 - 40
Friday Night SW 30 - 40 SW 35 - 45 SW 45 - 55 --- - SW 45 - 55
Saturday Morning WSW 25 - 35 WSW 35 - 45 W 30 - 40 --- - WSW 45 - 55
Saturday Afternoon - Saturday Night W 30 - 40 W 35 - 45 WNW 35 - 45 --- - WNW 35 - 45
Mt. Baker Direction - Speed
Friday Afternoon SW 30 - 40
Friday Night SW 30 - 40
Saturday Morning WSW 25 - 35
Saturday Afternoon - Saturday Night W 30 - 40
Washington Pass Direction - Speed
Friday Afternoon SW 15 - 25
Friday Night SW 35 - 45
Saturday Morning WSW 35 - 45
Saturday Afternoon - Saturday Night W 35 - 45
Stevens and Snoqualmie Pass Direction - Speed
Friday Afternoon SW 30 - 40
Friday Night SW 45 - 55
Saturday Morning W 30 - 40
Saturday Afternoon - Saturday Night WNW 35 - 45
Mt. Rainier Direction - Speed
Friday Afternoon --- -
Friday Night --- -
Saturday Morning --- -
Saturday Afternoon - Saturday Night --- -
Mt. Hood Direction - Speed
Friday Afternoon SW 30 - 40
Friday Night SW 45 - 55
Saturday Morning WSW 45 - 55
Saturday Afternoon - Saturday Night WNW 35 - 45

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.

Issued: 1:55 PM PDT Friday, April 10, 2015

Extended Weather Synopsis for Friday night through Friday

Westerly flow should ease on Sunday and snow levels should moderate a bit.  Mostly cloudy skies and leftover showers, especially over the northern half should linger as the next frontal system approaches from the west.  

The low pressure associated with the next system should curl toward the central B.C. coast Monday with precipitation from the frontal boundary reaching the Cascades by mid-day or afternoon and passing through Monday night.  A modest bump in snow levels should occur before the frontal passage. A generally unstable and cool air mass should be overhead on Tuesday. 

Extended Weather

Olympics, Washington Cascades and Mt. Hood area
Sunday - Sunday Evening

Cloudy north part with chance of light rain and snow showers. Slight warming trend. Mostly cloudy central and south Cascades including Mt. Hood. 

Sunday Night - Monday

Light rain and snow developing north Cascades and Olympics late Sunday night and spreading inland Monday. 

Monday Night

Light to occasionally moderate rain and snow becoming showers.

Tuesday

Mostly cloudy with scattered light to occasionally moderate rain and snow showers. Cooler. 

Extended Snow/Freezing Levels

Mt. Baker Snoqualmie Pass Mt. Hood Easterly Flow *
Sunday Morning Snow Level 1500' - 2500' 1500' - 3000' 2000' - 3000'
Sunday Afternoon - Monday Afternoon Snow Level 3000' - 4000' 3500' - 4500' 4500' - 5500'
Monday Night - Tuesday Snow Level 2500' - 3500' 2500' - 3500' 2500' - 3500'
Mt. Baker Elevation
Sunday Morning Snow Level
1500' - 2500'
Sunday Afternoon - Monday Afternoon Snow Level
3000' - 4000'
Monday Night - Tuesday Snow Level
2500' - 3500'
Snoqualmie Pass Elevation
Sunday Morning Snow Level
1500' - 3000'
Sunday Afternoon - Monday Afternoon Snow Level
3500' - 4500'
Monday Night - Tuesday Snow Level
2500' - 3500'
Mt. Hood Elevation
Sunday Morning Snow Level
2000' - 3000'
Sunday Afternoon - Monday Afternoon Snow Level
4500' - 5500'
Monday Night - Tuesday Snow Level
2500' - 3500'

* 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 Apr 10, 2015

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