Issued: 3:23 PM PDT Thursday, April 5, 2018
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 Thursday & Tuesday

A deep low pressure system well off the B.C. coast is spinning a N-S oriented front into the Pacific Northwest today. Light rain and snow already gracing the area will only increase in the afternoon as the front slowly works across the Cascades through the early evening. Snow levels hanging around 4500 ft in the north and 6000 ft at Mt. Hood this morning will slightly rise through the day. More moderate precipitation will continue through the evening hours before tapering down overnight.  

Friday is a relative break day with a dirty ridge building over the inland Pacific Northwest and the main tap of moisture aimed into northern California. A few periods of light rain are likely Friday. The south and central Cascades will likely see a few sunbreaks Friday morning through mid-day, with cloudier conditions expected over the north Cascades and down at Mt. Hood. Milder air will continue to work into the region. 

An impressive and developing low pressure system offshore will track NE toward Vancouver Island Friday night. The approaching frontal band will likely bring stormy conditions to the Cascades by early Saturday morning with snow levels peaking Friday night. The highest snow levels are currently pegged for the Olympics, and Snoqualmie Pass and southward. Offshore gradients will increase Friday night, but the air mass is too warm for easterly flow to have any cooling effect in the Passes. 

Weather Forecast

Olympics
Thursday Light rain and snow becoming light to occasionally moderate rain and snow in the afternoon.
Thursday Night Light rain and snow becoming cloudy with periods of light rain and snow in the evening.
Friday Mostly cloudy. Periods of light rain and snow. Milder.
Friday Night Cloudy with light rain and snow becoming light to moderate rain and snow late Friday night with increasing winds. Mild.
Washington Cascades near and west of the Crest including Stevens, Snoqualmie and White Passes
Thursday Light rain and snow becoming light to moderate rain and snow in the afternoon.
Thursday Night Light to moderate rain and snow becoming light after midnight.
Friday Mostly cloudy. Periods of light rain and snow. Milder.
Friday Night Cloudy with light rain and snow becoming moderate rain and snow south and central Cascades late Friday night with increasing winds. Mild.
East Slopes of the Washington Cascades
Thursday Light rain and snow becoming light to moderate rain and snow in the afternoon.
Thursday Night Light to moderate rain and snow becoming light after midnight.
Friday Mostly cloudy southeast and central-east, cloudy north. Periods of light rain and snow. Milder.
Friday Night Cloudy with light rain and snow becoming light to moderate rain and snow southeast and central-east Cascades late Friday night with increasing winds. Mild.
Mt. Hood
Thursday Light rain and snow becoming light to moderate rain and snow in the afternoon.
Thursday Night Light to moderate rain and snow becoming light after midnight.
Friday Cloudy. Periods of light rain and snow. Milder.
Friday Night Cloudy with light rain and snow becoming light to moderate rain and snow after midnight with increasing winds. Mild.

Issued: 3:23 PM PDT Thursday, April 5, 2018

Snow/Freezing Level (ft)

Hurricane Ridge Mt. Baker Washington Pass Leavenworth Stevens Pass Snoqualmie Pass Mt. Rainier, Crystal & White Pass Mt. Hood
Thursday Afternoon Snow Level 6000' 5500' 5500' ' ' 6000' ' 6500'
Thursday Evening Snow Level 7000' 6000' 5500' ' ' 6000' ' 7000'
Thursday Night Snow Level 6000' 6000' 5000' ' ' 7000' ' 7500'
Friday Morning Snow Level 5500' 5500' 5000' ' ' 6500' ' 7000'
Friday Afternoon Snow Level 6500' 6500' 6500' ' ' 7000' ' 8000'
Friday Night Snow Level 8500' 6500' 6000' ' ' 8500' ' 10000'
Hurricane Ridge Elevation
Thursday Afternoon Snow Level
6000'
Thursday Evening Snow Level
7000'
Thursday Night Snow Level
6000'
Friday Morning Snow Level
5500'
Friday Afternoon Snow Level
6500'
Friday Night Snow Level
8500'
Mt. Baker Elevation
Thursday Afternoon Snow Level
5500'
Thursday Evening Snow Level
6000'
Thursday Night Snow Level
6000'
Friday Morning Snow Level
5500'
Friday Afternoon Snow Level
6500'
Friday Night Snow Level
6500'
Washington Pass Elevation
Thursday Afternoon Snow Level
5500'
Thursday Evening Snow Level
5500'
Thursday Night Snow Level
5000'
Friday Morning Snow Level
5000'
Friday Afternoon Snow Level
6500'
Friday Night Snow Level
6000'
Leavenworth Elevation
Thursday Afternoon Snow Level
'
Thursday Evening Snow Level
'
Thursday Night Snow Level
'
Friday Morning Snow Level
'
Friday Afternoon Snow Level
'
Friday Night Snow Level
'
Stevens Pass Elevation
Thursday Afternoon Snow Level
'
Thursday Evening Snow Level
'
Thursday Night Snow Level
'
Friday Morning Snow Level
'
Friday Afternoon Snow Level
'
Friday Night Snow Level
'
Snoqualmie Pass Elevation
Thursday Afternoon Snow Level
6000'
Thursday Evening Snow Level
6000'
Thursday Night Snow Level
7000'
Friday Morning Snow Level
6500'
Friday Afternoon Snow Level
7000'
Friday Night Snow Level
8500'
Mt. Rainier & Crystal Elevation
Thursday Afternoon Snow Level
'
Thursday Evening Snow Level
'
Thursday Night Snow Level
'
Friday Morning Snow Level
'
Friday Afternoon Snow Level
'
Friday Night Snow Level
'
Mt. Hood Elevation
Thursday Afternoon Snow Level
6500'
Thursday Evening Snow Level
7000'
Thursday Night Snow Level
7500'
Friday Morning Snow Level
7000'
Friday Afternoon Snow Level
8000'
Friday Night Snow Level
10000'

* 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

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

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: 3:23 PM PDT Thursday, April 5, 2018

Free Winds at 5000' (mph)

Hurricane Ridge Mt. Baker Stevens to Snoqualmie Pass Mt. Rainier Mt. Hood
Thursday Afternoon SSW 15 - 25 SSE 10 - 20 SSE 10 - 20 --- - SW 5 - 15
Thursday Night S 10 - 20 S 10 - 20 SW 15 - 25 --- - WSW 10 - 20
Friday Morning S 5 - 15 SSE 10 - 20 SE 5 - 15 --- - SSE 0 - 10
Friday Afternoon SE 5 - 15 SE 5 - 15 SE 5 - 15 --- - SE 10 - 20
Friday Night ESE 15 - 25 E 10 - 20 E 15 - 30 --- - E 10 - 20
Hurricane Ridge Elevation
Thursday Afternoon SSW 15 - 25
Thursday Night S 10 - 20
Friday Morning S 5 - 15
Friday Afternoon SE 5 - 15
Friday Night ESE 15 - 25
Mt. Baker Elevation
Thursday Afternoon SSE 10 - 20
Thursday Night S 10 - 20
Friday Morning SSE 10 - 20
Friday Afternoon SE 5 - 15
Friday Night E 10 - 20
Stevens and Snoqualmie Pass Elevation
Thursday Afternoon SSE 10 - 20
Thursday Night SW 15 - 25
Friday Morning SE 5 - 15
Friday Afternoon SE 5 - 15
Friday Night E 15 - 30
Mt. Rainier Elevation
Thursday Afternoon --- -
Thursday Night --- -
Friday Morning --- -
Friday Afternoon --- -
Friday Night --- -
Mt. Hood Elevation
Thursday Afternoon SW 5 - 15
Thursday Night WSW 10 - 20
Friday Morning SSE 0 - 10
Friday Afternoon SE 10 - 20
Friday Night E 10 - 20
Hurricane Ridge Direction - Speed
Thursday Afternoon SSW 15 - 25
Thursday Night S 10 - 20
Friday Morning S 5 - 15
Friday Afternoon SE 5 - 15
Friday Night ESE 15 - 25
Mt. Baker Direction - Speed
Thursday Afternoon SSE 10 - 20
Thursday Night S 10 - 20
Friday Morning SSE 10 - 20
Friday Afternoon SE 5 - 15
Friday Night E 10 - 20
Stevens and Snoqualmie Pass Direction - Speed
Thursday Afternoon SSE 10 - 20
Thursday Night SW 15 - 25
Friday Morning SE 5 - 15
Friday Afternoon SE 5 - 15
Friday Night E 15 - 30
Mt. Rainier Direction - Speed
Thursday Afternoon --- -
Thursday Night --- -
Friday Morning --- -
Friday Afternoon --- -
Friday Night --- -
Mt. Hood Direction - Speed
Thursday Afternoon SW 5 - 15
Thursday Night WSW 10 - 20
Friday Morning SSE 0 - 10
Friday Afternoon SE 10 - 20
Friday Night E 10 - 20

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
Thursday Afternoon SSW 15 - 30 SW 10 - 20 SW 25 - 35 --- - SW 25 - 35
Thursday Night SW 15 - 25 SW 10 - 20 WSW 20 - 30 --- - SW 20 - 30
Friday Morning SW 10 - 20 SW 10 - 20 SW 10 - 20 --- - SW 10 - 20
Friday Afternoon S 10 - 20 SW 5 - 15 SW 10 - 20 --- - S 10 - 20
Friday Night SSE 15 - 25 SSE 10 - 20 S 25 - 35 --- - SW 30 - 40
Mt. Baker Direction - Speed
Thursday Afternoon SSW 15 - 30
Thursday Night SW 15 - 25
Friday Morning SW 10 - 20
Friday Afternoon S 10 - 20
Friday Night SSE 15 - 25
Washington Pass Direction - Speed
Thursday Afternoon SW 10 - 20
Thursday Night SW 10 - 20
Friday Morning SW 10 - 20
Friday Afternoon SW 5 - 15
Friday Night SSE 10 - 20
Stevens and Snoqualmie Pass Direction - Speed
Thursday Afternoon SW 25 - 35
Thursday Night WSW 20 - 30
Friday Morning SW 10 - 20
Friday Afternoon SW 10 - 20
Friday Night S 25 - 35
Mt. Rainier Direction - Speed
Thursday Afternoon --- -
Thursday Night --- -
Friday Morning --- -
Friday Afternoon --- -
Friday Night --- -
Mt. Hood Direction - Speed
Thursday Afternoon SW 25 - 35
Thursday Night SW 20 - 30
Friday Morning SW 10 - 20
Friday Afternoon S 10 - 20
Friday Night SW 30 - 40

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: 3:23 PM PDT Thursday, April 5, 2018

Extended Weather Synopsis for Tuesday night through Tuesday

The frontal boundary extending from the strong low pressure system off of Vancouver Island will pass from south to north over the area late Friday night through Saturday morning with locally heavy precipitation and high snow levels. There may be a lull in the precipitation mid-day, but showers will increase once again in the afternoon and especially overnight as the low pressure system remains stationary with secondary troughs rotating onshore.

Very windy conditions will develop Saturday and continue Saturday night. Snow levels will slowly lower Saturday afternoon and settle into the 4000-5000 ft range for the remainder of the weekend. As the low weakens further and begins to eject inland as an open trough Sunday, expect showers to continue but to be less intense. Strong upper level ridging will quickly build offshore Sunday and slide over the area on Monday, providing us with a dry and mild day. 

Extended Weather

Olympics, Washington Cascades and Mt. Hood Area
Saturday Stormy with moderate to occasionally heavy rain and snow in the morning becoming light to occasionally moderate showers in the afternoon. Mild in the morning, cooling trend in the afternoon. Very windy. Sunday Cloudy with light to occasionally moderate rain and snow showers. Monday Partly sunny in the north Cascades and Olympics, mostly sunny in central and south Cascades including Mt. Hood. Mild. Saturday Night Renewed moderate to occasionally heavy rain and snow showers. Windy. Sunday Night Mostly cloudy with scattered light rain and snow showers.

Extended Snow/Freezing Levels

Mt. Baker Snoqualmie Pass Mt. Hood Easterly Flow *
Saturday Morning Snow Level 5500' - 6500' 6000' - 7000' 6500' - 7500'
Saturday Night Snow Level 3500' - 4500' 3500' - 4500' 4000' - 5000'
Sunday Snow Level 4000' - 5000' 4000' - 5000' 4000' - 5000'
Sunday Night Snow Level 4000' - 5000' 4000' - 5000' 4000' - 5000'
Monday Freezing Level 6500' - 7500' 7000' - 8000' 8500' - 9500'
Saturday Afternoon Snow Level 4500' - 5500' 4500' - 5500' 4500' - 5500'
Mt. Baker Elevation
Saturday Morning Snow Level
5500' - 6500'
Saturday Night Snow Level
3500' - 4500'
Sunday Snow Level
4000' - 5000'
Sunday Night Snow Level
4000' - 5000'
Monday Freezing Level
6500' - 7500'
Saturday Afternoon Snow Level
4500' - 5500'
Snoqualmie Pass Elevation
Saturday Morning Snow Level
6000' - 7000'
Saturday Night Snow Level
3500' - 4500'
Sunday Snow Level
4000' - 5000'
Sunday Night Snow Level
4000' - 5000'
Monday Freezing Level
7000' - 8000'
Saturday Afternoon Snow Level
4500' - 5500'
Mt. Hood Elevation
Saturday Morning Snow Level
6500' - 7500'
Saturday Night Snow Level
4000' - 5000'
Sunday Snow Level
4000' - 5000'
Sunday Night Snow Level
4000' - 5000'
Monday Freezing Level
8500' - 9500'
Saturday Afternoon Snow Level
4500' - 5500'

* 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 5, 2018

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