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Mountain Weather Forecast

Issued: 3:06 PM PST Wednesday, March 29, 2017
by Dennis D'Amico

The NWAC program is administered by the USDA-Forest Service and operates from the National Weather Service Forecast Office in Seattle. NWAC services are made possible by important collaboration and support from a wide variety of federal, state and private cooperators.

Weather synopsis for Wednesday & Thursday

A developing low pressure system tracked off the NW tip of the Olympic peninsula and across central Vancouver Island this morning. Snow levels eventually rose to around 5500 feet in the Mt. Baker area to around 7500 feet in the Mt. Hood area by mid-day, also bumping above Pass levels by late morning. The cold front has sagged SE across the Cascades mid-day with post-frontal showers beginning this afternoon. Showers look heaviest for the Mt. Baker area this afternoon and then a convergence zone should form this evening and affect the central Washington Cascades. Snow levels should fall to 3000-3500 feet overnight as the trailing upper level trough moves over the area through the morning hours.  

Showers should decrease on Thursday and become isolated in the afternoon for the west slopes of the Cascades and Olympics. More sunshine should be seen for the east slopes of the Washington Cascades. An upper level ridge offshore will move over western Washington and Oregon Thursday night with generally dry conditions expected. 

Weather forecast for Wednesday & Thursday

Olympics
Date Weather
Wednesday Afternoon

Light to occasionally moderate rain and snow showers. 

Wednesday Night - Thursday Morning

Light to occasionally moderate rain and snow showers. Slow cooling trend. 

Thursday Afternoon

Mostly cloudy with isolated rain and snow showers and afternoon sunbreaks. 

Partly cloudy. 

Washington Cascades near and west of the crest including Stevens, Snoqualmie, and White Passes
Date Weather
Wednesday Afternoon

Light to moderate rain and snow showers, locally heavy Mt. Baker. Slow warming trend. 

Wednesday Night - Thursday Morning

Light to moderate rain and snow showers. Slow cooling trend. 

Thursday Afternoon

Mostly cloudy with isolated rain and snow showers and afternoon sunbreaks. 

Partly cloudy. 

East slopes of the Washington Cascades
Date Weather
Wednesday Afternoon

Light to occasionally moderate rain and snow showers. Slow warming trend. 

Wednesday Night - Thursday Morning

Mostly cloudy with light rain and snow showers. Slow cooling trend. 

Thursday Afternoon

Partly to mostly cloudy with isolated showers near the Cascade crest. 

Partly cloudy. 

Mt. Hood Area
Date Weather
Wednesday Afternoon

Moderate rain and snow showers.  

Wednesday Night - Thursday Morning

Light to occasionally moderate rain and snow showers. Cooling trend. 

Thursday Afternoon

Mostly cloudy with isolated rain and snow showers and afternoon sunbreaks. 

Partly cloudy. 

Snow Level/Freezing Level in feet

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Wednesday Mid-day Snow Level 6500' 5000' 5000' 6000' 7500'
Wednesday Afternoon Snow Level 5000' 5500' 5500' 5500' 6500'
Wednesday Night Snow Level 3500' 3500' 3500' 3500' 4000'
Thursday Morning Snow Level 3000' 3000' 3000' 3000' 3000'
Olympics
Date Elevation
Wednesday Mid-day Snow Level
6500'
Wednesday Afternoon Snow Level
5000'
Wednesday Night Snow Level
3500'
Thursday Morning Snow Level
3000'
Thursday Afternoon - Thursday Night Snow Level
400'
Northwest Cascades
Date Elevation
Wednesday Mid-day Snow Level
5000'
Wednesday Afternoon Snow Level
5500'
Wednesday Night Snow Level
3500'
Thursday Morning Snow Level
3000'
Thursday Afternoon - Thursday Night Snow Level
4000'
Northeast Cascades
Date Elevation
Wednesday Mid-day Snow Level
5000'
Wednesday Afternoon Snow Level
5500'
Wednesday Night Snow Level
3500'
Thursday Morning Snow Level
3000'
Thursday Afternoon - Thursday Night Snow Level
4000'
Central Cascades
Date Elevation
Wednesday Mid-day Snow Level
6000'
Wednesday Afternoon Snow Level
5500'
Wednesday Night Snow Level
3500'
Thursday Morning Snow Level
3000'
Thursday Afternoon - Thursday Night Snow Level
4000'
South Cascades
Date Elevation
Wednesday Mid-day Snow Level
7500'
Wednesday Afternoon Snow Level
6500'
Wednesday Night Snow Level
4000'
Thursday Morning Snow Level
3000'
Thursday Afternoon - Thursday Night Snow Level
4000'

Cascade Snow / Freezing Levels noted above refer to the north (approximately Mt Baker and Washington Pass), central (approximately Stevens to White Pass) and south (near Mt Hood). Freezing Level is when no precipitation is forecast.
* Note that surface snow levels are common near the passes during easterly pass flow and may result in multiple snow / freezing levels.

24 Hour Quantitative Precipitation ending at 4 am

Location Thu Fri
Hurricane Ridge .25 - .50 lt .10
Mt Baker Ski Area 1.50 .25
Washington Pass .50 - .75 lt .25
Stevens Pass 1.00 - 1.50 .25 - .50
Snoqualmie Pass 1.50 - 2.00 .25 - .50
Mission Ridge lt .25 0
Crystal Mt .75 .25
Paradise 1.50 - 2.00 .25 - .50
White Pass .75 - 1.00 lt .25
Mt Hood Meadows 1.50 - 2.00 .50

Winds in Miles per Hour (MPH) "Cascade Pass Level Winds"

Date Direction - Speed
Wednesday Mid-day E None - None
Wednesday Afternoon W 10 - 20
Wednesday Night - Thursday Morning W 15 - 25

Directions above indicate the direction the wind blows from on the 16-point cardinal scale. Winds near the passes tend to be highly channeled by the topography and normally blow either easterly or westerly depending on the surface pressure gradients that drive such winds.

Free Winds at 5000' (in Miles per Hour (MPH))

Date Olympics Northwest Cascades Central Cascades South Cascades
Wednesday Afternoon SW 15 - 25 WSW 20 - 35 WSW 25 - 35 WSW 25 - 40
Wednesday Night - Thursday Morning W 15 - 30 WSW 10 - 20 WSW 10 - 20 WNW 15 - 30
Thursday Afternoon WNW 0 - 10 W 0 - 10 WNW 5 - 15 WNW 20 - 30
Olympics
Date Elevation
Wednesday Afternoon SW 15 - 25
Wednesday Night - Thursday Morning W 15 - 30
Thursday Afternoon WNW 0 - 10
Thursday Night W 0 - 10
Northwest Cascades
Date Elevation
Wednesday Afternoon WSW 20 - 35
Wednesday Night - Thursday Morning WSW 10 - 20
Thursday Afternoon W 0 - 10
Thursday Night W 0 - 10
Central Cascades
Date Elevation
Wednesday Afternoon WSW 25 - 35
Wednesday Night - Thursday Morning WSW 10 - 20
Thursday Afternoon WNW 5 - 15
Thursday Night WNW 5 - 15
South Cascades
Date Elevation
Wednesday Afternoon WSW 25 - 40
Wednesday Night - Thursday Morning WNW 15 - 30
Thursday Afternoon WNW 20 - 30
Thursday Night NW 5 - 15
Olympics
Date Direction - Speed
Wednesday Afternoon SW 15 - 25
Wednesday Night - Thursday Morning W 15 - 30
Thursday Afternoon WNW 0 - 10
Thursday Night W 0 - 10
Northwest Cascades
Date Direction - Speed
Wednesday Afternoon WSW 20 - 35
Wednesday Night - Thursday Morning WSW 10 - 20
Thursday Afternoon W 0 - 10
Thursday Night W 0 - 10
Central Cascades
Date Direction - Speed
Wednesday Afternoon WSW 25 - 35
Wednesday Night - Thursday Morning WSW 10 - 20
Thursday Afternoon WNW 5 - 15
Thursday Night WNW 5 - 15
South Cascades
Date Direction - Speed
Wednesday Afternoon WSW 25 - 40
Wednesday Night - Thursday Morning WNW 15 - 30
Thursday Afternoon WNW 20 - 30
Thursday Night NW 5 - 15

Directions above indicate the direction the wind blows from on the 16-point cardinal scale. These winds and the 9000 ft winds below also 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' (in Miles per Hour (MPH))

Date Northwest Cascades Northeast Cascades Central Cascades South Cascades
Wednesday Mid-day - Wednesday Afternoon SW 30 - 40 SW 40 - 50 SW 45 - 55 WSW 50 - 60
Wednesday Night WSW 20 - 30 WSW 15 - 25 WSW 30 - 40 WSW 30 - 40
Thursday Morning WNW 15 - 25 WNW 25 - 35 NW 25 - 35 NW 35 - 45
Thursday Afternoon N 15 - 25 NW 20 - 30 NW 20 - 30 NW 30 - 40
Northwest Cascades
Date Direction - Speed
Wednesday Mid-day - Wednesday Afternoon SW 30 - 40
Wednesday Night WSW 20 - 30
Thursday Morning WNW 15 - 25
Thursday Afternoon N 15 - 25
Thursday Night N 15 - 25
Northeast Cascades
Date Direction - Speed
Wednesday Mid-day - Wednesday Afternoon SW 40 - 50
Wednesday Night WSW 15 - 25
Thursday Morning WNW 25 - 35
Thursday Afternoon NW 20 - 30
Thursday Night N 10 - 20
Central Cascades
Date Direction - Speed
Wednesday Mid-day - Wednesday Afternoon SW 45 - 55
Wednesday Night WSW 30 - 40
Thursday Morning NW 25 - 35
Thursday Afternoon NW 20 - 30
Thursday Night NNW 10 - 20
South Cascades
Date Direction - Speed
Wednesday Mid-day - Wednesday Afternoon WSW 50 - 60
Wednesday Night WSW 30 - 40
Thursday Morning NW 35 - 45
Thursday Afternoon NW 30 - 40
Thursday Night N 10 - 20

Extended Weather Synopsis for Friday through Sunday

The upper level ridge will move over the area on Friday providing us with a dry and mild day. Sunshine may become filtered in the afternoon as a weak frontal system over Vancouver Island begins to spread some high clouds inland, especially over the Olympics and north Cascades. The ridge will flatten and shift east Friday night with light rain and snow developing for the Olympics and north Cascades. As the front peters out and passes inland Saturday, a period of post-frontal showers is likely mainly for the west slopes of the Cascades while the east slopes of the Cascades and Mt. Hood should see a fair amount of sunshine on Saturday afternoon.  A deeper trough is forecast to move over the Pacific Northwest on Sunday. This should produce more widespread showers with falling snow levels. 

Extended Weather Forecast for Friday through Sunday

Olympics, Washington Cascades and Mt. Hood
Date Weather
Friday

Partly to mostly sunny. Milder. Increasing high clouds Olympics and north Cascades in the afternoon. 

Friday Night

Increasing clouds. Light rain and snow developing north Cascades and Olympics. 

Saturday

Mostly cloudy with scattered light rain and snow showers especially Olympics and west slopes of the Cascades. Becoming partly sunny Mt. Hood and east slopes of the Cascades. 

Saturday Night

Mostly cloudy. 

Snow/Freezing Levels

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Friday - Friday Night Freezing Level 6500' - 7500' 5000' - 6000' 5500' - 6500' 5500' - 6500' 7000' - 8000'
Saturday Snow Level 4500' - 5500' 4500' - 5500' 5000' - 6000' 5000' - 6000' 6000' - 7000'
Olympics
Date Elevation
Friday - Friday Night Freezing Level
6500' - 7500'
Saturday Snow Level
4500' - 5500'
Saturday Night - Sunday Snow Level
3000' - 4000'
Northwest Cascades
Date Elevation
Friday - Friday Night Freezing Level
5000' - 6000'
Saturday Snow Level
4500' - 5500'
Saturday Night - Sunday Snow Level
3000' - 4000'
Northeast Cascades
Date Elevation
Friday - Friday Night Freezing Level
5500' - 6500'
Saturday Snow Level
5000' - 6000'
Saturday Night - Sunday Snow Level
3000' - 4000'
Central Cascades
Date Elevation
Friday - Friday Night Freezing Level
5500' - 6500'
Saturday Snow Level
5000' - 6000'
Saturday Night - Sunday Snow Level
3000' - 4000'
South Cascades
Date Elevation
Friday - Friday Night Freezing Level
7000' - 8000'
Saturday Snow Level
6000' - 7000'
Saturday Night - Sunday Snow Level
3500' - 4500'

Freezing Level is when no precipitation is forecast.
* Note that surface snow levels are common near the passes during easterly pass flow and may result in multiple snow / freezing levels.