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Mountain Weather Forecast

Issued: 7:35 AM Monday, March 2, 2015
by Garth Ferber

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 Monday & Tuesday

The upper ridge that has been around nearly all winter will be about 600 miles west of the Northwest coast on Monday. A weak short wave in a north flow over the Northwest began to move south over the Olympics and north Cascades Sunday night and will finish moving south over the south Cascades Monday morning. A few light showers might still be seen in the south Cascades Monday morning but NWAC sites probably won't measure any precipitation. Snow levels dropped another notch Monday morning compared to Sunday.

Decreasing clouds with some partly or mostly sunny sky conditions should be seen in all areas by Monday afternoon with further clearing Monday night as a drier air mass moves into the Northwest. A shot of Arctic air should move south mainly east of the Rockies Monday afternoon and night. This should help cause a puff of northeast ridge top winds and east pass winds mainly in the Cascades Monday afternoon and night.

The upper ridge should shift a bit to the east to about 400 miles west of the Northwest coast on Tuesday. This should cause light north flow aloft over the Northwest and weak ridgetop winds and sunny weather in the Olympics and Cascades with a slight rise in the low freezing levels.

 

Weather forecast for Monday & Tuesday

Olympics
Date Weather
Monday Morning

Partly cloudy.

Monday Afternoon

Mostly sunny.

Monday Night

Mostly clear.

Washington Cascades near and west of the crest including Stevens, Snoqualmie, and White Passes
Date Weather
Monday Morning

Mostly cloudy with slight chance of a light shower south Cascades.

Monday Afternoon

Partly sunny.

Monday Night

Mostly clear.

East slopes of the Washington Cascades
Date Weather
Monday Morning

Partly cloudy north and mostly cloudy south.

Monday Afternoon

Mostly sunny.

Monday Night

Mostly clear.

Mt. Hood Area
Date Weather
Monday Morning

Mostly cloudy with slight chance of a light shower.

Monday Afternoon

Partly sunny.

Monday Night

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 2500' 2500' 2000' 2500' 3000'
Monday Afternoon Freezing Level 4000' 3500' 3500' 4000' 4500' *
Monday Night - Tuesday Morning Freezing Level 3000' 2000' 1000' 2500' 3500' *
Olympics
Date Elevation
Monday Morning Snow Level
2500'
Monday Afternoon Freezing Level
4000'
Easterly Flow*
Monday Night - Tuesday Morning Freezing Level
3000'
Easterly Flow*
Tuesday Afternoon - Tuesday Night Freezing Level
4500'
Northwest Cascades
Date Elevation
Monday Morning Snow Level
2500'
Monday Afternoon Freezing Level
3500'
Easterly Flow*
Monday Night - Tuesday Morning Freezing Level
2000'
Easterly Flow*
Tuesday Afternoon - Tuesday Night Freezing Level
3500'
Northeast Cascades
Date Elevation
Monday Morning Snow Level
2000'
Monday Afternoon Freezing Level
3500'
Easterly Flow*
Monday Night - Tuesday Morning Freezing Level
1000'
Easterly Flow*
Tuesday Afternoon - Tuesday Night Freezing Level
3500'
Central Cascades
Date Elevation
Monday Morning Snow Level
2500'
Monday Afternoon Freezing Level
4000'
Easterly Flow*
Monday Night - Tuesday Morning Freezing Level
2500'
Easterly Flow*
Tuesday Afternoon - Tuesday Night Freezing Level
4000'
South Cascades
Date Elevation
Monday Morning Snow Level
3000'
Monday Afternoon Freezing Level
4500'
Easterly Flow*
Monday Night - Tuesday Morning Freezing Level
3500'
Easterly Flow*
Tuesday Afternoon - Tuesday Night Freezing Level
5500'

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 0 0
Mt Baker Ski Area 0 0
Washington Pass 0 0
Stevens Pass 0 0
Snoqualmie Pass 0 0
Mission Ridge 0 0
Crystal Mt 0 0
Paradise 0 0
White Pass 0 0
Mt Hood Meadows 0 0

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

Date Direction - Speed
Monday Morning - Monday Afternoon VAR 0 - 10
Monday Night - Tuesday Morning E 10 - 20

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 NE 5 - 15 NE 5 - 15 NE 5 - 15 NE 5 - 15
Monday Afternoon - Tuesday Morning NE 10 - 20 NE 15 - 25 NE 15 - 25 NE 15 - 25
Tuesday Mid-day NE 5 - 15 NE 5 - 15 NE 5 - 15 NE 5 - 15
Olympics
Date Elevation
Monday Morning NE 5 - 15
Monday Afternoon - Tuesday Morning NE 10 - 20
Tuesday Mid-day NE 5 - 15
Tuesday Afternoon - Tuesday Night VAR 0 - 10
Northwest Cascades
Date Elevation
Monday Morning NE 5 - 15
Monday Afternoon - Tuesday Morning NE 15 - 25
Tuesday Mid-day NE 5 - 15
Tuesday Afternoon - Tuesday Night VAR 0 - 10
Central Cascades
Date Elevation
Monday Morning NE 5 - 15
Monday Afternoon - Tuesday Morning NE 15 - 25
Tuesday Mid-day NE 5 - 15
Tuesday Afternoon - Tuesday Night VAR 0 - 10
South Cascades
Date Elevation
Monday Morning NE 5 - 15
Monday Afternoon - Tuesday Morning NE 15 - 25
Tuesday Mid-day NE 5 - 15
Tuesday Afternoon - Tuesday Night VAR 0 - 10
Olympics
Date Direction - Speed
Monday Morning NE 5 - 15
Monday Afternoon - Tuesday Morning NE 10 - 20
Tuesday Mid-day NE 5 - 15
Tuesday Afternoon - Tuesday Night VAR 0 - 10
Northwest Cascades
Date Direction - Speed
Monday Morning NE 5 - 15
Monday Afternoon - Tuesday Morning NE 15 - 25
Tuesday Mid-day NE 5 - 15
Tuesday Afternoon - Tuesday Night VAR 0 - 10
Central Cascades
Date Direction - Speed
Monday Morning NE 5 - 15
Monday Afternoon - Tuesday Morning NE 15 - 25
Tuesday Mid-day NE 5 - 15
Tuesday Afternoon - Tuesday Night VAR 0 - 10
South Cascades
Date Direction - Speed
Monday Morning NE 5 - 15
Monday Afternoon - Tuesday Morning NE 15 - 25
Tuesday Mid-day NE 5 - 15
Tuesday Afternoon - Tuesday Night VAR 0 - 10

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 N 30 - 40 N 30 - 40 N 20 - 30 N 10 - 20
Monday Afternoon - Monday Night N 30 - 40 N 30 - 40 N 30 - 40 N 25 - 35
Tuesday Mid-day - Tuesday Afternoon NNW 15 - 25 NNW 15 - 25 NNW 15 - 25 NNW 15 - 25
Northwest Cascades
Date Direction - Speed
Monday Morning N 30 - 40
Monday Afternoon - Monday Night N 30 - 40
Tuesday Mid-day - Tuesday Afternoon NNW 15 - 25
Tuesday Night NW 15 - 25
Northeast Cascades
Date Direction - Speed
Monday Morning N 30 - 40
Monday Afternoon - Monday Night N 30 - 40
Tuesday Mid-day - Tuesday Afternoon NNW 15 - 25
Tuesday Night NW 15 - 25
Central Cascades
Date Direction - Speed
Monday Morning N 20 - 30
Monday Afternoon - Monday Night N 30 - 40
Tuesday Mid-day - Tuesday Afternoon NNW 15 - 25
Tuesday Night NW 15 - 25
South Cascades
Date Direction - Speed
Monday Morning N 10 - 20
Monday Afternoon - Monday Night N 25 - 35
Tuesday Mid-day - Tuesday Afternoon NNW 15 - 25
Tuesday Night NW 15 - 25

Extended Weather Synopsis for Wednesday through Friday

The upper ridge  and dry air mass should shift a bit to nearer the Northwest coast on Wednesday with sunny weather in the Olympics and Cascades with a bit further rise in freezing levels.

Some difference is seen the the 06 GMT GFS run and 00 GMT Euro run by later in the week. The GFS barely flattens the upper ridge over the Northwest on Thursday and Friday as a weak system moves mainly across BC. The Euro flattens the ridge more and allow a moderate system across south BC and the Olympics and north Cascades. A blend of these scenarios will indicated for now for the Thursday to Friday period.

Extended Weather Forecast for Wednesday through Friday

Olympics, Washington Cascades, Mt Hood
Date Weather
Wednesday

Mostly sunny and mostly clear.

Snow/Freezing Levels

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Wednesday Freezing Level 4000' - 6000' 3000' - 5000' 3000' - 5000' 4000' - 6000' 6000' - 8000' *
Thursday Freezing Level 6000' - 8000' 5000' - 7000' 5000' - 6000' 6000' - 8000' 7000' - 9000'
Olympics
Date Elevation
Wednesday Freezing Level
4000' - 6000'
Easterly Flow*
Thursday Freezing Level
6000' - 8000'
Friday Freezing Level
6000' - 8000'
Northwest Cascades
Date Elevation
Wednesday Freezing Level
3000' - 5000'
Easterly Flow*
Thursday Freezing Level
5000' - 7000'
Friday Freezing Level
6000' - 8000'
Northeast Cascades
Date Elevation
Wednesday Freezing Level
3000' - 5000'
Easterly Flow*
Thursday Freezing Level
5000' - 6000'
Friday Freezing Level
6000' - 8000'
Central Cascades
Date Elevation
Wednesday Freezing Level
4000' - 6000'
Easterly Flow*
Thursday Freezing Level
6000' - 8000'
Friday Freezing Level
6000' - 8000'
South Cascades
Date Elevation
Wednesday Freezing Level
6000' - 8000'
Easterly Flow*
Thursday Freezing Level
7000' - 9000'
Friday Freezing Level
7000' - 9000'

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.