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Mountain Weather Forecast

Issued: 8:32 AM PST Friday, April 28, 2017
by Kenny Kramer

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.

NWAC Spring Forecast Schedule

The NWAC issued daily mountain weather and avalanche forecasts through Saturday, April 15th. Mountain weather and avalanche forecasts will be issued during the spring transition April 20-22nd and April 27-29th. Weekend outlooks will be issued Thursdays, May 4th, 11th, 18th and 25th.

Weather synopsis for Friday & Saturday

Weak onshore flow is maintaining mainly low clouds early Friday morning in the wake of a passing disturbance Thursday. 

Upper level high pressure is rebuilding offshore early Friday and will slowly move over the region late Friday and early Saturday. Skies at mid and upper elevations are clearing fast early Friday as the web cam reveals Mt Rainier in all her glory Friday morning.

The ridge should cause further clearing through the day and a slow warming trend with light NW flow aloft.

Skies should remain mostly clear overnight as the ridge moves inland over the area.

An upper trough should ride over the ridge across the NE Pacific Saturday to flatten the ridge and increase westerly flow. A frontal system associated with the disturbance should spread increasing clouds across the Olympics and NW Washington Cascades early Saturday. Clouds should increase and spread to the remaining forecast areas through the day Saturday with light precipitation reaching the Olympics and Mt Baker area Saturday afternoon.

The main frontal passage should move across the Cacades Saturday night, bringing a period of light to moderate precipitation at moderate freezing levels.

Weather forecast for Friday & Saturday

Olympics
Date Weather
Friday

Mostly sunny with gradual warming. Light winds.

Friday Night

Partly or mostly clear in the evening. Increasing high clouds after midnight.

Saturday Morning

Increasing clouds becoming mostly cloudy.

Light rain and snow developing Saturday afternoon. Light to briefly moderate rain and snow Saturday night.

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

Areas of low clouds with a chance of showers, mainly Mt Baker area. Otherwise becoming mostly sunny higher elevations. Light winds.

Friday Afternoon

Partly or mostly sunny.

Friday Night

Partly or mostly clear.

Saturday

Increasing high clouds. Clouds lowering in the north with a chance of light rain or snow Saturday afternoon.

Light rain and snow developing in the north Saturday afternoon and in the central and south by evening or early Saturday night. Light to briefly moderate rain and snow Saturday night.

East slopes of the Washington Cascades
Date Weather
Friday

Mostly sunny.

Friday Night

Mostly clear.

Saturday

Increasing high clouds.

Periods of light rain and snow.

Mt. Hood Area
Date Weather
Friday

Mostly sunny.

Friday Night

Partly or mostly clear.

Saturday

Clear early with increasing high clouds.

Light rain and snow developing Saturday evening. Light to briefly moderate rain and snow Saturday night.

Snow Level/Freezing Level in feet

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Friday Morning Freezing Level 4000' 4000' 4000' 4000' 4500'
Friday Afternoon - Saturday Morning Freezing Level 5500' 5500' 5500' 5500' 6000'
Olympics
Date Elevation
Friday Morning Freezing Level
4000'
Friday Afternoon - Saturday Morning Freezing Level
5500'
Friday Afternoon - Friday Night Snow Level
5000'
Northwest Cascades
Date Elevation
Friday Morning Freezing Level
4000'
Friday Afternoon - Saturday Morning Freezing Level
5500'
Friday Afternoon - Friday Night Snow Level
5000'
Northeast Cascades
Date Elevation
Friday Morning Freezing Level
4000'
Friday Afternoon - Saturday Morning Freezing Level
5500'
Friday Afternoon - Friday Night Snow Level
5000'
Central Cascades
Date Elevation
Friday Morning Freezing Level
4000'
Friday Afternoon - Saturday Morning Freezing Level
5500'
Friday Afternoon - Friday Night Snow Level
5500'
South Cascades
Date Elevation
Friday Morning Freezing Level
4500'
Friday Afternoon - Saturday Morning Freezing Level
6000'
Friday Afternoon - Friday Night Snow Level
6500'

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 Sat Sun
Hurricane Ridge 0 lt .25
Mt Baker Ski Area lt .10 .50
Washington Pass 0 lt .25
Stevens Pass 0 .25
Snoqualmie Pass 0 .25
Mission Ridge 0 lt .25
Crystal Mt 0 lt .25
Paradise 0 .25 - .50
White Pass 0 lt .25
Mt Hood Meadows 0 .25

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

Date Direction - Speed

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
Friday - Friday WNW 10 - 20 WNW 5 - 15 WNW 10 - 20 WNW 10 - 20
Friday Night WNW 5 - 15 WNW 5 - 15 WNW 5 - 15 WNW 10 - 20
Saturday Morning SW 0 - 10 SW 0 - 10 SW 0 - 10 WSW 0 - 10
Saturday Afternoon SSW 20 - 30 SSW 15 - 25 SW 10 - 20 WSW 10 - 20
Olympics
Date Elevation
Friday - Friday WNW 10 - 20
Friday Night WNW 5 - 15
Saturday Morning SW 0 - 10
Saturday Afternoon SSW 20 - 30
Saturday Night SW 15 - 25
Northwest Cascades
Date Elevation
Friday - Friday WNW 5 - 15
Friday Night WNW 5 - 15
Saturday Morning SW 0 - 10
Saturday Afternoon SSW 15 - 25
Saturday Night SW 15 - 25
Central Cascades
Date Elevation
Friday - Friday WNW 10 - 20
Friday Night WNW 5 - 15
Saturday Morning SW 0 - 10
Saturday Afternoon SW 10 - 20
Saturday Night SW 25 - 35
South Cascades
Date Elevation
Friday - Friday WNW 10 - 20
Friday Night WNW 10 - 20
Saturday Morning WSW 0 - 10
Saturday Afternoon WSW 10 - 20
Saturday Night SW 20 - 30
Olympics
Date Direction - Speed
Friday - Friday WNW 10 - 20
Friday Night WNW 5 - 15
Saturday Morning SW 0 - 10
Saturday Afternoon SSW 20 - 30
Saturday Night SW 15 - 25
Northwest Cascades
Date Direction - Speed
Friday - Friday WNW 5 - 15
Friday Night WNW 5 - 15
Saturday Morning SW 0 - 10
Saturday Afternoon SSW 15 - 25
Saturday Night SW 15 - 25
Central Cascades
Date Direction - Speed
Friday - Friday WNW 10 - 20
Friday Night WNW 5 - 15
Saturday Morning SW 0 - 10
Saturday Afternoon SW 10 - 20
Saturday Night SW 25 - 35
South Cascades
Date Direction - Speed
Friday - Friday WNW 10 - 20
Friday Night WNW 10 - 20
Saturday Morning WSW 0 - 10
Saturday Afternoon WSW 10 - 20
Saturday Night SW 20 - 30

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
Friday Morning NNW 5 - 10 NNW 5 - 10 NNW 5 - 15 NNW 10 - 20
Friday Afternoon - Friday Night WNW 5 - 15 WNW 5 - 15 WNW 5 - 15 WNW 5 - 15
Saturday Morning W 15 - 25 W 5 - 15 W 10 - 20 W 10 - 20
Northwest Cascades
Date Direction - Speed
Friday Morning NNW 5 - 10
Friday Afternoon - Friday Night WNW 5 - 15
Saturday Morning W 15 - 25
Saturday Afternoon - Saturday Night W 30 - 40
Northeast Cascades
Date Direction - Speed
Friday Morning NNW 5 - 10
Friday Afternoon - Friday Night WNW 5 - 15
Saturday Morning W 5 - 15
Saturday Afternoon - Saturday Night W 30 - 40
Central Cascades
Date Direction - Speed
Friday Morning NNW 5 - 15
Friday Afternoon - Friday Night WNW 5 - 15
Saturday Morning W 10 - 20
Saturday Afternoon - Saturday Night W 30 - 40
South Cascades
Date Direction - Speed
Friday Morning NNW 10 - 20
Friday Afternoon - Friday Night WNW 5 - 15
Saturday Morning W 10 - 20
Saturday Afternoon - Saturday Night W 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.

The Extended Mountain Weather Forecast (Days 3-5) will be included with the afternoon forecast issuance around 1:30 PM.