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Mountain Weather Forecast

Issued: 3:21 PM PST Saturday, April 22, 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.

Weather synopsis for Saturday & Sunday

Well, one day of nice spring weather per week is better than none. That would have been yesterday, in case you missed it. That weather is now in the distant rear view mirror, as the upper ridge responsible has exited stage east by Saturday afternoon.

A return to an active weather pattern in the PNW for this coming week is well underway. 

An upper trough is now in place well offshore with an east to west oriented trough extending across Washington. An associated band of precipitation is rotating northward and has mostly passed the forecast area Saturday afternoon. Additional shower bands have activated across the central WA Cascades Saturday afternoon. Somewhat unstable air will maintain periods of generally light showers Saturday afternoon and evening, before tapering or ending overnight.

A brief break in precipitation is expected later Saturday night through early Sunday before the next wave arrives midday and through Sunday afternoon. The weak upper flow will turn more onshore Sunday to maintain the greatest precipitation over the west slope areas and volcanoes through Sunday evening. The upper level trough will remain offshore, maintaining unsettled and cooler conditions with periods of showers or steady precipitation at times heading into next week.

Weather forecast for Saturday & Sunday

Olympics
Date Weather
Saturday Afternoon - Sunday Morning

Mostly cloudy with light rain and snow showers tapering or ending overnight through early Sunday. 

Renewed light to occasionally moderate rain and snow showers. Showers diminishing overnight.

Washington Cascades near and west of the crest including Stevens, Snoqualmie, and White Passes
Date Weather
Saturday Afternoon - Sunday Morning

Mostly cloudy with light rain and snow showers tapering or ending overnight through early Sunday, except occasionally light to moderate showers persisting in the Mt. Baker area. 

Renewed light to occasionally moderate rain and snow showers. Showers diminishing overnight.

East slopes of the Washington Cascades
Date Weather
Saturday Afternoon - Sunday Morning

Partly to mostly cloudy with isolated light rain and snow showers ending in the evening through early Sunday.  

Renewed light rain and snow showers. Showers diminishing overnight.

Mt. Hood Area
Date Weather
Saturday Afternoon - Saturday Night

Mostly cloudy with isolated light rain and snow showers in the afternoon, ending overnight and becoming partly cloudy. 

Renewed light to moderate rain and snow showers Sunday morning through Sunday afternoon. Showers diminishing overnight.

Snow Level/Freezing Level in feet

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Saturday Afternoon Snow Level 5500' 5500' 5500' 5500' 6000' *
Saturday Night Snow Level 4000' 4000' 4000' 4000' 4500'
Sunday Snow Level 4000' 4500' 4500' 4500' 5000'
Olympics
Date Elevation
Saturday Afternoon Snow Level
5500'
Easterly Flow*
Saturday Night Snow Level
4000'
Sunday Snow Level
4000'
Sunday Night Snow Level
3500'
Northwest Cascades
Date Elevation
Saturday Afternoon Snow Level
5500'
Easterly Flow*
Saturday Night Snow Level
4000'
Sunday Snow Level
4500'
Sunday Night Snow Level
3500'
Northeast Cascades
Date Elevation
Saturday Afternoon Snow Level
5500'
Easterly Flow*
Saturday Night Snow Level
4000'
Sunday Snow Level
4500'
Sunday Night Snow Level
3500'
Central Cascades
Date Elevation
Saturday Afternoon Snow Level
5500'
Easterly Flow*
Saturday Night Snow Level
4000'
Sunday Snow Level
4500'
Sunday Night Snow Level
3500'
South Cascades
Date Elevation
Saturday Afternoon Snow Level
6000'
Easterly Flow*
Saturday Night Snow Level
4500'
Sunday Snow Level
5000'
Sunday 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 Sun Mon
Hurricane Ridge .25 .25
Mt Baker Ski Area .50 .50
Washington Pass lt .25 lt .25
Stevens Pass .25 .25 - .50
Snoqualmie Pass .25 .25 - .50
Mission Ridge lt .10 lt .25
Crystal Mt .25 .25 - .50
Paradise .25 .75
White Pass lt .25 .25 - .50
Mt Hood Meadows lt .25 .75

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

Date Direction - Speed
Saturday Afternoon W 10 - 15
Saturday Night - Sunday W 5 - 15

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
Saturday Afternoon SSW 15 - 25 S 15 - 25 SW 15 - 25 SW 15 - 25
Saturday Night - Sunday Morning SW 0 - 10 S 5 - 15 SW 0 - 10 WSW 5 - 15
Olympics
Date Elevation
Saturday Afternoon SSW 15 - 25
Saturday Night - Sunday Morning SW 0 - 10
Sunday Afternoon - Sunday Night SW 5 - 15
Northwest Cascades
Date Elevation
Saturday Afternoon S 15 - 25
Saturday Night - Sunday Morning S 5 - 15
Sunday Afternoon - Sunday Night SW 5 - 15
Central Cascades
Date Elevation
Saturday Afternoon SW 15 - 25
Saturday Night - Sunday Morning SW 0 - 10
Sunday Afternoon - Sunday Night SW 10 - 20
South Cascades
Date Elevation
Saturday Afternoon SW 15 - 25
Saturday Night - Sunday Morning WSW 5 - 15
Sunday Afternoon - Sunday Night SW 10 - 20
Olympics
Date Direction - Speed
Saturday Afternoon SSW 15 - 25
Saturday Night - Sunday Morning SW 0 - 10
Sunday Afternoon - Sunday Night SW 5 - 15
Northwest Cascades
Date Direction - Speed
Saturday Afternoon S 15 - 25
Saturday Night - Sunday Morning S 5 - 15
Sunday Afternoon - Sunday Night SW 5 - 15
Central Cascades
Date Direction - Speed
Saturday Afternoon SW 15 - 25
Saturday Night - Sunday Morning SW 0 - 10
Sunday Afternoon - Sunday Night SW 10 - 20
South Cascades
Date Direction - Speed
Saturday Afternoon SW 15 - 25
Saturday Night - Sunday Morning WSW 5 - 15
Sunday Afternoon - Sunday Night SW 10 - 20

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
Saturday Afternoon SW 25 - 35 SW 15 - 25 SW 20 - 30 SW 25 - 35
Saturday Night - Sunday Morning SW 5 - 15 WSW 5 - 15 WSW 10 - 20 SW 20 - 30
Northwest Cascades
Date Direction - Speed
Saturday Afternoon SW 25 - 35
Saturday Night - Sunday Morning SW 5 - 15
Sunday Afternoon - Sunday Night SW 10 - 20
Northeast Cascades
Date Direction - Speed
Saturday Afternoon SW 15 - 25
Saturday Night - Sunday Morning WSW 5 - 15
Sunday Afternoon - Sunday Night SW 10 - 20
Central Cascades
Date Direction - Speed
Saturday Afternoon SW 20 - 30
Saturday Night - Sunday Morning WSW 10 - 20
Sunday Afternoon - Sunday Night SW 20 - 30
South Cascades
Date Direction - Speed
Saturday Afternoon SW 25 - 35
Saturday Night - Sunday Morning SW 20 - 30
Sunday Afternoon - Sunday Night SW 25 - 35

Extended Weather Synopsis for Monday through Wednesday

An upper and surface low pressure system is expected to develop offshore of southern Oregon Sunday night and early Monday with a strong jet directed towards northern California. The heaviest precipitation looks to be centered on the southern Washington Cascades and Mt. Hood Monday through Tuesday, with even greater energy directed across Oregon and northern California to the south of the forecast area. However, there will be periods of moderate precipitation over all areas as the quasi-stationary upper low off of Vancouver Island ejects inland.

The upper low offshore should eject slowly across the region Wednesday.

This pattern will maintain relatively low snow levels with periods of moderate precipitation during individual disturbance passages, with brief breaks at time. Timing of the impulses in the extended forecast is difficult to pinpoint, but suffice it to say, it will be an overall active pattern this coming week. 

Extended Weather Forecast for Monday through Wednesday

Olympics, Washington Cascades and Mt. Hood
Date Weather
Monday

Light to moderate rain and snow over the Olympics spreading inland to Mt. Hood, and the south and central Washington Cascades. Light rain and snow north Cascades. 

Snow/Freezing Levels

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Monday Snow Level 3500' - 4500' 3500' - 4500' 3500' - 4500' 3500' - 4500' 3500' - 4500'
Monday Afternoon Snow Level 4500' - 5500' 4500' - 5500' 4500' - 5500' 4500' - 5500' 4500' - 5500'
Monday Night - Tuesday Morning Snow Level 3500' - 4500' 3500' - 4500' 3500' - 4500' 3500' - 4500' 3500' - 4500'
Tuesday Afternoon Snow Level 4000' - 5000' 4000' - 5000' 4000' - 5000' 4000' - 5000' 4500' - 5500'
Olympics
Date Elevation
Monday Snow Level
3500' - 4500'
Monday Afternoon Snow Level
4500' - 5500'
Monday Night - Tuesday Morning Snow Level
3500' - 4500'
Tuesday Afternoon Snow Level
4000' - 5000'
Tuesday Night - Wednesday Snow Level
3500' - 4500'
Northwest Cascades
Date Elevation
Monday Snow Level
3500' - 4500'
Monday Afternoon Snow Level
4500' - 5500'
Monday Night - Tuesday Morning Snow Level
3500' - 4500'
Tuesday Afternoon Snow Level
4000' - 5000'
Tuesday Night - Wednesday Snow Level
3500' - 4500'
Northeast Cascades
Date Elevation
Monday Snow Level
3500' - 4500'
Monday Afternoon Snow Level
4500' - 5500'
Monday Night - Tuesday Morning Snow Level
3500' - 4500'
Tuesday Afternoon Snow Level
4000' - 5000'
Tuesday Night - Wednesday Snow Level
3500' - 4500'
Central Cascades
Date Elevation
Monday Snow Level
3500' - 4500'
Monday Afternoon Snow Level
4500' - 5500'
Monday Night - Tuesday Morning Snow Level
3500' - 4500'
Tuesday Afternoon Snow Level
4000' - 5000'
Tuesday Night - Wednesday Snow Level
3500' - 4500'
South Cascades
Date Elevation
Monday Snow Level
3500' - 4500'
Monday Afternoon Snow Level
4500' - 5500'
Monday Night - Tuesday Morning Snow Level
3500' - 4500'
Tuesday Afternoon Snow Level
4500' - 5500'
Tuesday Night - Wednesday 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.