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Mountain Weather Forecast

Issued: 2:58 PM PST Tuesday, March 6, 2018
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 Tuesday & Wednesday

Upper level ridging will build offshore today with a dry and eventually sunny day forecast across the Pacific Northwest. Before the sunshine, a mid level cloud deck is hanging tough around for the Olympics and central and north Cascades this morning while clearer skies are seen further south.  In the cloudier areas, skies should clear later this morning with just some afternoon cumulus buildup expected.  Mostly clear and dry weather will continue overnight. 

Flat upper level ridging will move over the region on Wednesday, with freezing levels rising further. However, a closed upper low well off the California coast will spread mid and high clouds over the region from the south during the day, dampening an otherwise warm day for early March.  A weakening frontal band extending from the low pressure system will pass over the area Wednesday night producing light precipitation. 

Weather forecast for Tuesday & Wednesday

Olympics
Date Weather
Tuesday Partly to mostly sunny.
Tuesday Night Mostly clear.
Wednesday Mostly cloudy becoming cloudy with increasing mid and high level clouds during the day. Mild.
Light rain and snow developing after midnight.
Washington Cascades near and west of the Crest including Stevens, Snoqualmie and White Passes
Date Weather
Tuesday Partly to mostly sunny north Cascades. Mostly sunny central and south.
Tuesday Night Mostly clear.
Wednesday Mostly cloudy becoming cloudy with increasing mid and high level clouds during the day. Mild.
Light rain and snow developing after midnight.
East Slopes of the Washington Cascades
Date Weather
Tuesday Partly to mostly sunny northeast Cascades. Mostly sunny central-east and southeast.
Tuesday Night Mostly clear.
Wednesday Mostly cloudy becoming cloudy with increasing mid and high level clouds during the day. Mild.
Light rain and snow developing after midnight.
Mt. Hood
Date Weather
Tuesday Mostly sunny.
Tuesday Night Mostly clear.
Wednesday Mostly cloudy becoming cloudy with increasing mid and high level clouds during the day. Mild.
Light rain and snow developing.

Snow Level/Freezing Level in feet

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Tuesday Afternoon Freezing Level 3500' 3500' 4000' 4000' 5000'
Tuesday Night Freezing Level 3500' 2000' 500' 2000' 4500'
Wednesday Morning Freezing Level 4500' 3500' 3000' 4000' 6000'
Wednesday Afternoon Freezing Level 7000' 6000' 5500' 6500' 8000'
Olympics
Date Elevation
Tuesday Afternoon Freezing Level
3500'
Tuesday Night Freezing Level
3500'
Wednesday Morning Freezing Level
4500'
Wednesday Afternoon Freezing Level
7000'
Wednesday Night Snow Level
4500'
Easterly Flow*
Northwest Cascades
Date Elevation
Tuesday Afternoon Freezing Level
3500'
Tuesday Night Freezing Level
2000'
Wednesday Morning Freezing Level
3500'
Wednesday Afternoon Freezing Level
6000'
Wednesday Night Snow Level
4000'
Easterly Flow*
Northeast Cascades
Date Elevation
Tuesday Afternoon Freezing Level
4000'
Tuesday Night Freezing Level
500'
Wednesday Morning Freezing Level
3000'
Wednesday Afternoon Freezing Level
5500'
Wednesday Night Snow Level
3000'
Easterly Flow*
Central Cascades
Date Elevation
Tuesday Afternoon Freezing Level
4000'
Tuesday Night Freezing Level
2000'
Wednesday Morning Freezing Level
4000'
Wednesday Afternoon Freezing Level
6500'
Wednesday Night Snow Level
4000'
Easterly Flow*
South Cascades
Date Elevation
Tuesday Afternoon Freezing Level
5000'
Tuesday Night Freezing Level
4500'
Wednesday Morning Freezing Level
6000'
Wednesday Afternoon Freezing Level
8000'
Wednesday Night Snow Level
4500'
Easterly Flow*

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 Wed Thu
Hurricane Ridge 0 lt .10
Mt Baker Ski Area 0 lt .10
Washington Pass 0 lt .10
Stevens Pass 0 lt .10
Snoqualmie Pass 0 lt .25
Mission Ridge 0 lt .10
Crystal Mt 0 lt .10
Paradise 0 lt .25
White Pass 0 lt .10
Mt Hood Meadows 0 lt .10

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

Date Direction - Speed
Tuesday Afternoon E 0 - 10
Tuesday Night E 10 - 20
Wednesday E 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
Tuesday Afternoon VAR 0 - 10 VAR 0 - 10 E 0 - 10 E 0 - 10
Tuesday Night E 0 - 10 S 0 - 10 E 5 - 15 SE 0 - 10
Wednesday Morning SE 0 - 10 SE 0 - 10 E 5 - 15 SE 5 - 15
Wednesday Afternoon S 0 - 10 SE 0 - 10 SE 5 - 15 SE 5 - 15
Olympics
Date Elevation
Tuesday Afternoon VAR 0 - 10
Tuesday Night E 0 - 10
Wednesday Morning SE 0 - 10
Wednesday Afternoon S 0 - 10
Wednesday Night S 10 - 20
Northwest Cascades
Date Elevation
Tuesday Afternoon VAR 0 - 10
Tuesday Night S 0 - 10
Wednesday Morning SE 0 - 10
Wednesday Afternoon SE 0 - 10
Wednesday Night SE 5 - 15
Central Cascades
Date Elevation
Tuesday Afternoon E 0 - 10
Tuesday Night E 5 - 15
Wednesday Morning E 5 - 15
Wednesday Afternoon SE 5 - 15
Wednesday Night SE 5 - 15
South Cascades
Date Elevation
Tuesday Afternoon E 0 - 10
Tuesday Night SE 0 - 10
Wednesday Morning SE 5 - 15
Wednesday Afternoon SE 5 - 15
Wednesday Night SW 5 - 15
Olympics
Date Direction - Speed
Tuesday Afternoon VAR 0 - 10
Tuesday Night E 0 - 10
Wednesday Morning SE 0 - 10
Wednesday Afternoon S 0 - 10
Wednesday Night S 10 - 20
Northwest Cascades
Date Direction - Speed
Tuesday Afternoon VAR 0 - 10
Tuesday Night S 0 - 10
Wednesday Morning SE 0 - 10
Wednesday Afternoon SE 0 - 10
Wednesday Night SE 5 - 15
Central Cascades
Date Direction - Speed
Tuesday Afternoon E 0 - 10
Tuesday Night E 5 - 15
Wednesday Morning E 5 - 15
Wednesday Afternoon SE 5 - 15
Wednesday Night SE 5 - 15
South Cascades
Date Direction - Speed
Tuesday Afternoon E 0 - 10
Tuesday Night SE 0 - 10
Wednesday Morning SE 5 - 15
Wednesday Afternoon SE 5 - 15
Wednesday Night SW 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
Tuesday Afternoon W 10 - 20 WSW 5 - 15 W 10 - 20 SW 10 - 20
Tuesday Night SW 10 - 20 SW 10 - 20 SW 10 - 20 SW 15 - 25
Wednesday Morning SW 10 - 20 SW 10 - 20 SW 15 - 25 SW 10 - 20
Wednesday Afternoon SW 15 - 25 SW 15 - 25 SW 15 - 25 SSW 15 - 25
Northwest Cascades
Date Direction - Speed
Tuesday Afternoon W 10 - 20
Tuesday Night SW 10 - 20
Wednesday Morning SW 10 - 20
Wednesday Afternoon SW 15 - 25
Wednesday Night SW 15 - 25
Northeast Cascades
Date Direction - Speed
Tuesday Afternoon WSW 5 - 15
Tuesday Night SW 10 - 20
Wednesday Morning SW 10 - 20
Wednesday Afternoon SW 15 - 25
Wednesday Night SW 15 - 25
Central Cascades
Date Direction - Speed
Tuesday Afternoon W 10 - 20
Tuesday Night SW 10 - 20
Wednesday Morning SW 15 - 25
Wednesday Afternoon SW 15 - 25
Wednesday Night SW 25 - 35
South Cascades
Date Direction - Speed
Tuesday Afternoon SW 10 - 20
Tuesday Night SW 15 - 25
Wednesday Morning SW 10 - 20
Wednesday Afternoon SSW 15 - 25
Wednesday Night SW 25 - 35

Extended Weather Synopsis for Thursday through Saturday

The weather pattern will quickly turn more active beginning Thursday as the upper level ridge over the area on Wednesday shifts inland. The aforementioned low pressure system will track towards the NW tip of the Olympic Peninsula on Thursday, passing into southern British Columbia Thursday evening. This system should pack a good punch of precipitation and winds as it traverses the area. With the current track, SW flow will keep snow levels in 4000-4500 range over much of the area Thursday and Thursday evening.  It remains to be seen how much if any effect easterly flow has on precipitation type in the Passes this late in the year. Winds will peak Thursday afternoon and evening. Behind the front a slow cooling trend should ensue Thursday night with much colder air moving Friday. Significant post-frontal shower activity will wane Friday afternoon as upper level ridging begins to build over the area. Saturday looks mostly dry, but forecast models disagree if an embedded shortwave in southerly flow will bring some cloud cover.  

Extended Weather Forecast for Thursday through Saturday

Olympics, Washington Cascades and Mt. Hood Area
Date Weather
Thursday Periods of light rain and snow in the morning becoming light to moderate rain and snow in the afternoon. Winds increasing through the day, becoming strong in the alpine in the afternoon.
Thursday Night Light to moderate rain and snow showers. Windy
Friday Light to moderate rain and snow showers in the morning becoming scattered light to occasionally moderate showers in the afternoon. Cooling trend.
Friday Night Mostly cloudy with showers tapering off overnight.

Snow/Freezing Levels

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Thursday Snow Level 4000' - 5000' 3500' - 4500' 3500' - 4500' 4000' - 4500' 4000' - 5000' *
Thursday Night Snow Level 3500' - 4500' 3500' - 4500' 3500' - 4500' 3500' - 4500' 4500' - 5500'
Friday Snow Level 2000' - 3000' 2000' - 3000' 2000' - 3000' 2000' - 3000' 3000' - 4000'
Friday Night Snow Level 2000' - 3000' 1500' - 2500' 2500' - 3500' 1500' - 2500' 3000' - 4000'
Olympics
Date Elevation
Thursday Snow Level
4000' - 5000'
Easterly Flow*
Thursday Night Snow Level
3500' - 4500'
Friday Snow Level
2000' - 3000'
Friday Night Snow Level
2000' - 3000'
Saturday Freezing Level
3500' - 4500'
Northwest Cascades
Date Elevation
Thursday Snow Level
3500' - 4500'
Easterly Flow*
Thursday Night Snow Level
3500' - 4500'
Friday Snow Level
2000' - 3000'
Friday Night Snow Level
1500' - 2500'
Saturday Freezing Level
3500' - 4500'
Northeast Cascades
Date Elevation
Thursday Snow Level
3500' - 4500'
Easterly Flow*
Thursday Night Snow Level
3500' - 4500'
Friday Snow Level
2000' - 3000'
Friday Night Snow Level
2500' - 3500'
Saturday Freezing Level
3500' - 4500'
Central Cascades
Date Elevation
Thursday Snow Level
4000' - 4500'
Easterly Flow*
Thursday Night Snow Level
3500' - 4500'
Friday Snow Level
2000' - 3000'
Friday Night Snow Level
1500' - 2500'
Saturday Freezing Level
3500' - 4500'
South Cascades
Date Elevation
Thursday Snow Level
4000' - 5000'
Easterly Flow*
Thursday Night Snow Level
4500' - 5500'
Friday Snow Level
3000' - 4000'
Friday Night Snow Level
3000' - 4000'
Saturday Freezing Level
4500' - 5500'

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.