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Mountain Weather Forecast

Issued: 8:02 AM Sunday, February 1, 2015
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 Sunday & Monday

An Pacific frontal system should bring a light to moderate amount of precipitation to the PNW mountains today. This front will be the first of a series of weather disturbances spinning from the parent upper level low well offshore out at 155W/45N over the next several days. 

After the front passes through the Cascades in late afternoon... a switch to westerly winds should temporarily bump up snow levels for Snoqualmie Pass.  Showers should diminish overnight. 

Another developing system approaching the area on Monday, with most of it's energy and moisture directed into Oregon.  This system should also bring a shot of warmer air that affects mainly from Snoqualmie Pass down to Mt. Hood in the afternoon and evening.  This system should move through quickly with showers again tapering down Monday night.   

Weather forecast for Sunday & Monday

North Washington Cascades near and west of the crest including Stevens Pass
Date Weather
Sunday Morning

Periods of light rain and snow. 

Sunday Afternoon

Light to moderate rain and snow.  Slight warming trend in the afternoon. 

Sunday Night - Monday Morning

Light rain and snow showers ending overnight and becoming mostly cloudy. 

Monday Afternoon - Monday Evening

Light rain and snow developing mid-day, occasionally moderate Stevens Pass. Slight warming trend Monday afternoon.  

South and Central Washington Cascades near and west of the crest including Snoqualmie, and White Passes and Olypmics
Date Weather
Sunday Morning

Periods of light rain and snow. 

Sunday Afternoon

Light to moderate rain and snow.  Warming trend in the afternoon. 

Sunday Night - Monday Morning

Light rain and snow showers ending overnight and becoming mostly cloudy. 

Monday Afternoon - Monday Evening

Light rain and snow developing mid-day and becoming moderate south Washington Cascades. Warming trend Monday afternoon.  Snow potentially mixing with freezing rain Snoqualmie Pass Monday afternoon before changing to rain in the early evening. 

East slopes of the Washington Cascades
Date Weather
Sunday Morning

Periods of light rain and snow, mainly northeast Cascades. 

Sunday Afternoon

Light to moderate rain and snow.  Slight warming trend in the afternoon. 

Sunday Night - Monday Morning

Scattered rain and snow showers ending overnight and becoming mostly cloudy. 

Monday Afternoon - Monday Evening

Light rain and snow developing mid-day, occasionally moderate near the crest central and southeast Cascades. Slight warming trend Monday afternoon.  

Mt. Hood Area
Date Weather
Sunday Morning

Periods of light rain and snow. 

Sunday Afternoon

Light to moderate rain and snow.  Warming trend in the afternoon. 

Sunday Night

Light rain and snow showers tapering down overnight and becoming mostly cloudy. 

Monday

Light rain and snow developing in the morning and becoming moderate to occasionally heavy mid-day. Warming trend Monday. 

Snow Level/Freezing Level in feet

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Sunday Morning Snow Level 4500' 4000' 2500' 3500' 5000' *
Sunday Mid-day Snow Level 5500' 3500' 3000' 3000' 5000' *
Sunday Afternoon Snow Level 5000' 4000' 4000' 5000' 6000'
Sunday Night - Morning Snow Level 4000' 3500' 3000' 4000' 5500'
Monday Mid-day Snow Level 4500' 3000' 3000' 4000' 6500' *
Monday Afternoon Snow Level 5000' 3500' 3500' 5500' 6000' *
Olympics
Date Elevation
Sunday Morning Snow Level
4500'
Easterly Flow*
Sunday Mid-day Snow Level
5500'
Easterly Flow*
Sunday Afternoon Snow Level
5000'
Sunday Night - Morning Snow Level
4000'
Monday Mid-day Snow Level
4500'
Easterly Flow*
Monday Afternoon Snow Level
5000'
Easterly Flow*
Monday Night Snow Level
4000'
Northwest Cascades
Date Elevation
Sunday Morning Snow Level
4000'
Easterly Flow*
Sunday Mid-day Snow Level
3500'
Easterly Flow*
Sunday Afternoon Snow Level
4000'
Sunday Night - Morning Snow Level
3500'
Monday Mid-day Snow Level
3000'
Easterly Flow*
Monday Afternoon Snow Level
3500'
Easterly Flow*
Monday Night Snow Level
3500'
Northeast Cascades
Date Elevation
Sunday Morning Snow Level
2500'
Easterly Flow*
Sunday Mid-day Snow Level
3000'
Easterly Flow*
Sunday Afternoon Snow Level
4000'
Sunday Night - Morning Snow Level
3000'
Monday Mid-day Snow Level
3000'
Easterly Flow*
Monday Afternoon Snow Level
3500'
Easterly Flow*
Monday Night Snow Level
3500'
Central Cascades
Date Elevation
Sunday Morning Snow Level
3500'
Easterly Flow*
Sunday Mid-day Snow Level
3000'
Easterly Flow*
Sunday Afternoon Snow Level
5000'
Sunday Night - Morning Snow Level
4000'
Monday Mid-day Snow Level
4000'
Easterly Flow*
Monday Afternoon Snow Level
5500'
Easterly Flow*
Monday Night Snow Level
4000'
South Cascades
Date Elevation
Sunday Morning Snow Level
5000'
Easterly Flow*
Sunday Mid-day Snow Level
5000'
Easterly Flow*
Sunday Afternoon Snow Level
6000'
Sunday Night - Morning Snow Level
5500'
Monday Mid-day Snow Level
6500'
Easterly Flow*
Monday Afternoon Snow Level
6000'
Easterly Flow*
Monday Night Snow Level
4500'

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 Mon Tue
Hurricane Ridge lt .25 lt .25
Mt Baker Ski Area .50 .25
Washington Pass .25 lt .25
Stevens Pass .50 .50
Snoqualmie Pass .50 .50
Mission Ridge lt .25 lt .10
Crystal Mt .25 .25 - .50
Paradise .50 - .75 .75 - 1.00
White Pass .25 - .50 .25 - .50
Mt Hood Meadows .75 - 1.00 1.00

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

Date Direction - Speed
Sunday Morning - Sunday Mid-day E 10 - 20
Sunday Afternoon - Sunday Evening W 5 - 15
Sunday Night - Monday Afternoon E 0 - 10

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
Sunday Morning SW 10 - 20 SE 5 - 15 SE 5 - 15 SW 5 - 15
Sunday Afternoon W 10 - 20 SW 10 - 20 SW 15 - 25 WSW 15 - 25
Sunday Night - Monday Morning SW 5 - 15 S 5 - 15 SW 5 - 15 SW 10 - 20
Monday Afternoon SW 5 - 15 SW 5 - 15 SW 20 - 30 WSW 25 - 35
Olympics
Date Elevation
Sunday Morning SW 10 - 20
Sunday Afternoon W 10 - 20
Sunday Night - Monday Morning SW 5 - 15
Monday Afternoon SW 5 - 15
Monday Night W 5 - 15
Northwest Cascades
Date Elevation
Sunday Morning SE 5 - 15
Sunday Afternoon SW 10 - 20
Sunday Night - Monday Morning S 5 - 15
Monday Afternoon SW 5 - 15
Monday Night SW 10 - 20
Central Cascades
Date Elevation
Sunday Morning SE 5 - 15
Sunday Afternoon SW 15 - 25
Sunday Night - Monday Morning SW 5 - 15
Monday Afternoon SW 20 - 30
Monday Night W 10 - 20
South Cascades
Date Elevation
Sunday Morning SW 5 - 15
Sunday Afternoon WSW 15 - 25
Sunday Night - Monday Morning SW 10 - 20
Monday Afternoon WSW 25 - 35
Monday Night W 15 - 25
Olympics
Date Direction - Speed
Sunday Morning SW 10 - 20
Sunday Afternoon W 10 - 20
Sunday Night - Monday Morning SW 5 - 15
Monday Afternoon SW 5 - 15
Monday Night W 5 - 15
Northwest Cascades
Date Direction - Speed
Sunday Morning SE 5 - 15
Sunday Afternoon SW 10 - 20
Sunday Night - Monday Morning S 5 - 15
Monday Afternoon SW 5 - 15
Monday Night SW 10 - 20
Central Cascades
Date Direction - Speed
Sunday Morning SE 5 - 15
Sunday Afternoon SW 15 - 25
Sunday Night - Monday Morning SW 5 - 15
Monday Afternoon SW 20 - 30
Monday Night W 10 - 20
South Cascades
Date Direction - Speed
Sunday Morning SW 5 - 15
Sunday Afternoon WSW 15 - 25
Sunday Night - Monday Morning SW 10 - 20
Monday Afternoon WSW 25 - 35
Monday Night W 15 - 25

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
Sunday Morning WSW 20 - 30 WSW 20 - 30 WSW 25 - 35 W 25 - 35
Sunday Afternoon WSW 30 - 40 W 35 - 45 WSW 35 - 45 W 30 - 40
Sunday Night - Monday Morning W 20 - 30 WNW 20 - 30 W 25 - 35 W 30 - 40
Monday Afternoon W 30 - 40 W 30 - 40 WSW 40 - 50 W 50 - 60
Northwest Cascades
Date Direction - Speed
Sunday Morning WSW 20 - 30
Sunday Afternoon WSW 30 - 40
Sunday Night - Monday Morning W 20 - 30
Monday Afternoon W 30 - 40
Monday Night W 15 - 25
Northeast Cascades
Date Direction - Speed
Sunday Morning WSW 20 - 30
Sunday Afternoon W 35 - 45
Sunday Night - Monday Morning WNW 20 - 30
Monday Afternoon W 30 - 40
Monday Night WNW 30 - 40
Central Cascades
Date Direction - Speed
Sunday Morning WSW 25 - 35
Sunday Afternoon WSW 35 - 45
Sunday Night - Monday Morning W 25 - 35
Monday Afternoon WSW 40 - 50
Monday Night NW 25 - 35
South Cascades
Date Direction - Speed
Sunday Morning W 25 - 35
Sunday Afternoon W 30 - 40
Sunday Night - Monday Morning W 30 - 40
Monday Afternoon W 50 - 60
Monday Night W 30 - 40

Extended Weather Synopsis for Tuesday through Thursday

Yet another developing frontal wave extending from the upper low well offshore should approach the area on Tuesday.  This system looks rather weak and should mainly affect the Mt. Hood area with some light to occasionally moderate precipitation.

Upper level ridging should build along the west coast on Wednesday for at least some partial clearing.  A stronger system will develop in SW flow aloft for Thursday and spread over the area.  This pattern will likely stick around through the weekend bringing bouts of mild and wet weather.   

Extended Weather Forecast for Tuesday through Thursday

Olympics and Washington Cascades
Date Weather
Tuesday

Periods of light rain and snow, heaviest south Washington Cascades and Mt. Hood area. 

Tuesday Night

Mostly cloudy with isolated rain and snow showers. 

Wednesday - Wednesday Night

Partly sunny Wednesday with increasing high clouds in the afternoon.  Becoming cloudy overnight. 

Snow/Freezing Levels

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

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.