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Mountain Weather Forecast

Issued: 9:38 AM PST Monday, March 5, 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.

930 AM: Corrected Typo in East Slopes Forecast. 

Weather synopsis for Monday & Tuesday

The Pacific Northwest will stay in cool NW flow aloft with scattered light snow showers and generally cloudy skies expected for today. An area of convergence west of Stevens Pass this morning will break up during the day. There may be a few sunbreaks poking through in the afternoon. Moderate west winds in the Mt. Hood area will slowly decrease this afternoon. 

Flat upper level ridging will move over the area Tuesday, providing us with a dry and fair weather day.  Afternoon cumulus buildup looks to be trapped near ridgecrest as warmer air moves in aloft and prevents a full clearing trend.  The other weather impact will be slightly warmer temperatures along with the early March sunshine.  Dry weather will continue Tuesday night. 

Weather forecast for Monday & Tuesday

Olympics
Date Weather
Monday Cloudy with scattered light snow showers this morning. Mostly cloudy with light isolated showers in the afternoon.
Monday Night Partly to mostly clear.
Tuesday Mostly clear in the morning, becoming partly sunny with cumulus building in the afternoon. Slight warming trend.
Mostly clear.
Washington Cascades near and west of the Crest including Stevens, Snoqualmie and White Passes
Date Weather
Monday Cloudy with scattered light snow showers, locally moderate near a convergence zone this morning west of Stevens Pass. Mostly cloudy with light isolated showers in the afternoon.
Monday Night Partly to mostly clear.
Tuesday Mostly clear in the morning, becoming partly sunny with cumulus building in the afternoon. Slight warming trend.
Mostly clear.
East Slopes of the Washington Cascades
Date Weather
Monday Cloudy with isolated light snow showers near the Cascade crest this morning, becoming mostly cloudy with light isolated showers in the afternoon.
Monday Night Mostly clear.
Tuesday Mostly clear in the morning, becoming partly sunny with cumulus building in the afternoon near the Cascade Crest. Slight warming trend.
Mostly clear.
Mt. Hood
Date Weather
Monday Cloudy with scattered light snow showers this morning. Mostly cloudy with light isolated showers in the afternoon. Moderate West winds decreasing in the afternoon.
Monday Night Partly to mostly clear.
Tuesday Mostly clear in the morning, becoming partly sunny with cumulus building in the afternoon. Slight warming trend.
Mostly clear.

Snow Level/Freezing Level in feet

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Monday Morning Snow Level 500' 500' 0' 1000' 1500'
Monday Afternoon Snow Level 2000' 1500' 1500' 2000' 3000'
Monday Night Snow Level 1500' 1500' 500' 1000' 2500'
Tuesday Morning Freezing Level 1500' 1500' 1000' 1000' 2500'
Tuesday Afternoon Freezing Level 3500' 3000' 4000' 4000' 5000'
Olympics
Date Elevation
Monday Morning Snow Level
500'
Monday Afternoon Snow Level
2000'
Monday Night Snow Level
1500'
Tuesday Morning Freezing Level
1500'
Tuesday Afternoon Freezing Level
3500'
Tuesday Night Freezing Level
3500'
Northwest Cascades
Date Elevation
Monday Morning Snow Level
500'
Monday Afternoon Snow Level
1500'
Monday Night Snow Level
1500'
Tuesday Morning Freezing Level
1500'
Tuesday Afternoon Freezing Level
3000'
Tuesday Night Freezing Level
2500'
Northeast Cascades
Date Elevation
Monday Morning Snow Level
0'
Monday Afternoon Snow Level
1500'
Monday Night Snow Level
500'
Tuesday Morning Freezing Level
1000'
Tuesday Afternoon Freezing Level
4000'
Tuesday Night Freezing Level
500'
Central Cascades
Date Elevation
Monday Morning Snow Level
1000'
Monday Afternoon Snow Level
2000'
Monday Night Snow Level
1000'
Tuesday Morning Freezing Level
1000'
Tuesday Afternoon Freezing Level
4000'
Tuesday Night Freezing Level
2000'
South Cascades
Date Elevation
Monday Morning Snow Level
1500'
Monday Afternoon Snow Level
3000'
Monday Night Snow Level
2500'
Tuesday Morning Freezing Level
2500'
Tuesday Afternoon Freezing Level
5000'
Tuesday Night Freezing 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 Tue Wed
Hurricane Ridge lt .10 0
Mt Baker Ski Area lt .25 0
Washington Pass lt .10 0
Stevens Pass lt .25 0
Snoqualmie Pass lt .25 0
Mission Ridge 0 0
Crystal Mt lt .10 0
Paradise lt .25 0
White Pass lt .25 0
Mt Hood Meadows lt .25 0

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

Date Direction - Speed
Monday Morning W 10 - 20
Monday Afternoon W 5 - 15
Monday Night VAR 0 - 10
Tuesday Morning E 5 - 15
Tuesday 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
Monday Morning W 5 - 15 SW 5 - 15 W 10 - 20 SW 151 - 30
Monday Afternoon W 5 - 15 SW 0 - 10 WSW 5 - 15 W 10 - 20
Monday Night W 0 - 10 W 0 - 10 W 0 - 10 W 0 - 10
Tuesday Morning WNW 5 - 15 W 0 - 10 WNW 5 - 15 W 5 - 15
Tuesday Afternoon W 5 - 15 SW 5 - 15 WSW 5 - 15 W 10 - 20
Olympics
Date Elevation
Monday Morning W 5 - 15
Monday Afternoon W 5 - 15
Monday Night W 0 - 10
Tuesday Morning WNW 5 - 15
Tuesday Afternoon W 5 - 15
Tuesday Night SW 10 - 20
Northwest Cascades
Date Elevation
Monday Morning SW 5 - 15
Monday Afternoon SW 0 - 10
Monday Night W 0 - 10
Tuesday Morning W 0 - 10
Tuesday Afternoon SW 5 - 15
Tuesday Night SW 10 - 20
Central Cascades
Date Elevation
Monday Morning W 10 - 20
Monday Afternoon WSW 5 - 15
Monday Night W 0 - 10
Tuesday Morning WNW 5 - 15
Tuesday Afternoon WSW 5 - 15
Tuesday Night SW 10 - 20
South Cascades
Date Elevation
Monday Morning SW 151 - 30
Monday Afternoon W 10 - 20
Monday Night W 0 - 10
Tuesday Morning W 5 - 15
Tuesday Afternoon W 10 - 20
Tuesday Night SW 15 - 25
Olympics
Date Direction - Speed
Monday Morning W 5 - 15
Monday Afternoon W 5 - 15
Monday Night W 0 - 10
Tuesday Morning WNW 5 - 15
Tuesday Afternoon W 5 - 15
Tuesday Night SW 10 - 20
Northwest Cascades
Date Direction - Speed
Monday Morning SW 5 - 15
Monday Afternoon SW 0 - 10
Monday Night W 0 - 10
Tuesday Morning W 0 - 10
Tuesday Afternoon SW 5 - 15
Tuesday Night SW 10 - 20
Central Cascades
Date Direction - Speed
Monday Morning W 10 - 20
Monday Afternoon WSW 5 - 15
Monday Night W 0 - 10
Tuesday Morning WNW 5 - 15
Tuesday Afternoon WSW 5 - 15
Tuesday Night SW 10 - 20
South Cascades
Date Direction - Speed
Monday Morning SW 151 - 30
Monday Afternoon W 10 - 20
Monday Night W 0 - 10
Tuesday Morning W 5 - 15
Tuesday Afternoon W 10 - 20
Tuesday Night SW 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
Monday Morning W 10 - 20 W 15 - 25 W 15 - 25 W 20 - 30
Monday Afternoon W 10 - 20 W 10 - 20 WNW 15 - 25 WNW 15 - 25
Monday Night W 5 - 15 W 5 - 15 WNW 5 - 15 W 10 - 20
Tuesday Morning WNW 5 - 15 W 0 - 10 WNW 5 - 15 W 5 - 15
Tuesday Afternoon W 5 - 15 SW 5 - 15 WSW 5 - 15 W 10 - 20
Northwest Cascades
Date Direction - Speed
Monday Morning W 10 - 20
Monday Afternoon W 10 - 20
Monday Night W 5 - 15
Tuesday Morning WNW 5 - 15
Tuesday Afternoon W 5 - 15
Tuesday Night SW 10 - 20
Northeast Cascades
Date Direction - Speed
Monday Morning W 15 - 25
Monday Afternoon W 10 - 20
Monday Night W 5 - 15
Tuesday Morning W 0 - 10
Tuesday Afternoon SW 5 - 15
Tuesday Night SW 10 - 20
Central Cascades
Date Direction - Speed
Monday Morning W 15 - 25
Monday Afternoon WNW 15 - 25
Monday Night WNW 5 - 15
Tuesday Morning WNW 5 - 15
Tuesday Afternoon WSW 5 - 15
Tuesday Night SW 10 - 20
South Cascades
Date Direction - Speed
Monday Morning W 20 - 30
Monday Afternoon WNW 15 - 25
Monday Night W 10 - 20
Tuesday Morning W 5 - 15
Tuesday Afternoon W 10 - 20
Tuesday Night SW 5 - 15

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 between 2 - 3 PM.