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Mountain Weather Forecast

Issued: 1:23 PM PST Thursday, February 23, 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 Thursday & Friday

A slightly unstable air mass remains over the Pacific Northwest Thursday with cool, weak northerly flow aloft. This pattern is causing mostly cloudy conditions Thursday afternoon with some light snow shower activity over the mountains, mainly from the central WA Cascades southward to the Mt Hood area.

Light showers should continue through the afternoon and evening before tapering with relatively light winds at all elevations and low snow levels.

Another disturbance is expected to form off the west coast of B.C. Thursday night, forming a weak low pressure center off the NW Washington coast by Friday morning. This weak disturbance should trigger greater shower activity Friday, especially in the Olympics and over the Mt  Hood area Friday afternoon as the low pressure center tracks southward offshore. Light winds and low snow levels should persist Friday. Showers should diminish or end Friday night as high pressure rebuilds along the coast.

Weather forecast for Thursday & Friday

Olympics
Date Weather
Thursday - Thursday Night

Partly to mostly cloudy with scattered light snow showers, mainly afternoon hours. Cool.

Friday

Mostly cloudy with light to occasional moderate snow showers.  

Washington Cascades near and west of the crest including Stevens, Snoqualmie, and White Passes
Date Weather
Thursday - Thursday Night

Partly to mostly cloudy with scattered light snow showers, mainly afternoon hours. Cool.

Friday

Mostly cloudy with light snow showers north part and light to occasional moderate snow showers central and south part.  

East slopes of the Washington Cascades
Date Weather
Thursday - Thursday Night

Partly to mostly cloudy with isolated light snow showers, mainly afternoon hours.  Afternoon sunbreaks. Cool.

Mt. Hood Area
Date Weather
Thursday - Thursday Night

Partly to mostly cloudy with scattered light snow showers, mainly afternoon hours. Cool.  

Friday

Mostly cloudy with light to occasional moderate snow showers. Cool. 

Snow Level/Freezing Level in feet

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Thursday Afternoon - Thursday Evening Snow Level 1500' 1500' 1500' 1500' 2000'
Thursday Night - Friday Mid-day Snow Level 500' 500' 0' 500' 1000'
Friday Afternoon - Friday Evening Snow Level 1500' 1500' 1500' 1500' 2000'
Olympics
Date Elevation
Thursday Afternoon - Thursday Evening Snow Level
1500'
Thursday Night - Friday Mid-day Snow Level
500'
Friday Afternoon - Friday Evening Snow Level
1500'
Friday Night Snow Level
500'
Northwest Cascades
Date Elevation
Thursday Afternoon - Thursday Evening Snow Level
1500'
Thursday Night - Friday Mid-day Snow Level
500'
Friday Afternoon - Friday Evening Snow Level
1500'
Friday Night Snow Level
500'
Northeast Cascades
Date Elevation
Thursday Afternoon - Thursday Evening Snow Level
1500'
Thursday Night - Friday Mid-day Snow Level
0'
Friday Afternoon - Friday Evening Snow Level
1500'
Friday Night Snow Level
0'
Central Cascades
Date Elevation
Thursday Afternoon - Thursday Evening Snow Level
1500'
Thursday Night - Friday Mid-day Snow Level
500'
Friday Afternoon - Friday Evening Snow Level
1500'
Friday Night Snow Level
500'
South Cascades
Date Elevation
Thursday Afternoon - Thursday Evening Snow Level
2000'
Thursday Night - Friday Mid-day Snow Level
1000'
Friday Afternoon - Friday Evening Snow Level
2000'
Friday Night Snow Level
1000'

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

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

Date Direction - Speed
Thursday Afternoon W 0 - 10
Thursday Night VAR 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
Thursday Afternoon NW 0 - 10 NW 0 - 10 NW 0 - 10 NW 5 - 15
Thursday Night W 0 - 10 SSE 0 - 10 WNW 0 - 10 WNW 5 - 15
Friday SW 0 - 10 SSW 0 - 10 SW 5 - 15 W 5 - 15
Olympics
Date Elevation
Thursday Afternoon NW 0 - 10
Thursday Night W 0 - 10
Friday SW 0 - 10
Friday Night E 0 - 10
Northwest Cascades
Date Elevation
Thursday Afternoon NW 0 - 10
Thursday Night SSE 0 - 10
Friday SSW 0 - 10
Friday Night E 0 - 10
Central Cascades
Date Elevation
Thursday Afternoon NW 0 - 10
Thursday Night WNW 0 - 10
Friday SW 5 - 15
Friday Night SE 5 - 15
South Cascades
Date Elevation
Thursday Afternoon NW 5 - 15
Thursday Night WNW 5 - 15
Friday W 5 - 15
Friday Night SSW 5 - 15
Olympics
Date Direction - Speed
Thursday Afternoon NW 0 - 10
Thursday Night W 0 - 10
Friday SW 0 - 10
Friday Night E 0 - 10
Northwest Cascades
Date Direction - Speed
Thursday Afternoon NW 0 - 10
Thursday Night SSE 0 - 10
Friday SSW 0 - 10
Friday Night E 0 - 10
Central Cascades
Date Direction - Speed
Thursday Afternoon NW 0 - 10
Thursday Night WNW 0 - 10
Friday SW 5 - 15
Friday Night SE 5 - 15
South Cascades
Date Direction - Speed
Thursday Afternoon NW 5 - 15
Thursday Night WNW 5 - 15
Friday W 5 - 15
Friday Night SSW 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
Thursday Afternoon NNW 5 - 15 NNW 5 - 15 NW 5 - 15 NW 5 - 15
Thursday Night WNW 5 - 15 WNW 5 - 15 WNW 5 - 15 WNW 5 - 15
Friday SW 5 - 15 SW 5 - 15 WSW 5 - 15 W 10 - 20
Northwest Cascades
Date Direction - Speed
Thursday Afternoon NNW 5 - 15
Thursday Night WNW 5 - 15
Friday SW 5 - 15
Friday Night W 5 - 15
Northeast Cascades
Date Direction - Speed
Thursday Afternoon NNW 5 - 15
Thursday Night WNW 5 - 15
Friday SW 5 - 15
Friday Night W 5 - 15
Central Cascades
Date Direction - Speed
Thursday Afternoon NW 5 - 15
Thursday Night WNW 5 - 15
Friday WSW 5 - 15
Friday Night NNW 5 - 15
South Cascades
Date Direction - Speed
Thursday Afternoon NW 5 - 15
Thursday Night WNW 5 - 15
Friday W 10 - 20
Friday Night SSE 5 - 15

Extended Weather Synopsis for Saturday through Monday

A low pressure center continues its southerly track well offshore, heading towards central California by early Saturday as a brief ridge of high pressure builds over the coastal areas. This should provide a relatively clear day Saturday, with some afternoon clouds building and a chance of a few isolated showers mainly along the cascade crest.

Another similarly tracking low pressure system will move southwards off the B.C. coast Saturday night to renew showers through Sunday, especially during the afternoon. Continued low snow levels and light winds are expected Sunday.

Diminishing showers are expected Sunday night, becoming scattered or isolated Monday, remaining cool with light winds under continued weak NNW flow aloft. 

Extended Weather Forecast for Saturday through Monday

Olympics, Washington Cascades and Mt. Hood
Date Weather
Saturday

Partly sunny and cool early Saturday. Becoming partly to mostly cloudy in the afternoon with a chance of light snow showers.

Saturday Night - Sunday

Becoming mostly cloudy Saturday night with increasing light snow showers. Light to moderate snow showers Sunday, diminishing Sunday night becoming scattered.

Snow/Freezing Levels

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Saturday Freezing Level 1500' - 2500' 1500' - 2500' 1500' - 2500' 1500' - 2500' 2500' - 3500'
Saturday Night - Monday Night Snow Level 1000' - 2000' 1000' - 2000' 1000' - 2000' 1000' - 2000' 1500' - 2500'
Olympics
Date Elevation
Saturday Freezing Level
1500' - 2500'
Saturday Night - Monday Night Snow Level
1000' - 2000'
Monday Snow Level
None' - None'
Northwest Cascades
Date Elevation
Saturday Freezing Level
1500' - 2500'
Saturday Night - Monday Night Snow Level
1000' - 2000'
Monday Snow Level
None' - None'
Northeast Cascades
Date Elevation
Saturday Freezing Level
1500' - 2500'
Saturday Night - Monday Night Snow Level
1000' - 2000'
Monday Snow Level
None' - None'
Central Cascades
Date Elevation
Saturday Freezing Level
1500' - 2500'
Saturday Night - Monday Night Snow Level
1000' - 2000'
Monday Snow Level
None' - None'
South Cascades
Date Elevation
Saturday Freezing Level
2500' - 3500'
Saturday Night - Monday Night Snow Level
1500' - 2500'
Monday Snow Level
None' - None'

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.