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Mountain Weather Forecast

Issued: 4:03 PM PST Saturday, April 28, 2018
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 Saturday & Sunday

The Pacific Northwest is under the influence of a large upper level low pressure system centered over SW Washington Saturday afternoon. This is producing cool and showery weather across the forecast region. The remnants of an organized band of showers is maintaining steady precipitation over the Olympics Saturday afternoon with most other areas across the Cascades receiving periodic showers.

The upper low will continue to weaken and drift slowly eastwards overnight and Sunday. The cool upper low system will combine with low level moisture from onshore flow to maintain the showery pattern through Sunday. Due to the showery nature of the precipitation it will be difficult to forecast accurately where the greatest precipitation will fall, however in general the overall amounts should not be significant. 

 

 

Weather forecast for Saturday & Sunday

Olympics
Date Weather
Saturday Afternoon Cloudy with diminishing light rain and snow showers.
Saturday Night Cloudy with light rain and snow showers.
Sunday Mostly cloudy with rain and snow showers.
Mostly cloudy with rain and snow showers.
Washington Cascades near and west of the Crest including Stevens, Snoqualmie and White Passes
Date Weather
Saturday Afternoon Mostly cloudy with widespread rain and snow showers.
Saturday Night Cloudy with light rain and snow showers.
Sunday Mostly cloudy with rain and snow showers.
Mostly cloudy with rain and snow showers.
East Slopes of the Washington Cascades
Date Weather
Saturday Afternoon Mostly cloudy with rain and snow showers.
Saturday Night Mostly cloudy with scattered rain and snow showers.
Sunday Mostly cloudy with scattered rain and snow showers.
Mostly cloudy with scattered rain and snow showers.
Mt. Hood
Date Weather
Saturday Afternoon Mostly cloudy with rain and snow showers.
Saturday Night Mostly cloudy with rain and snow showers.
Sunday Mostly cloudy with rain and snow showers.
Mostly cloudy with rain and snow showers.

Snow Level/Freezing Level in feet

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Saturday Afternoon Snow Level 5000' 5000' 5500' 5000' 5500'
Saturday Night Snow Level 4500' 4500' 4500' 4500' 5000'
Sunday Snow Level 5000' 5000' 5500' 5000' 5000'
Olympics
Date Elevation
Saturday Afternoon Snow Level
5000'
Saturday Night Snow Level
4500'
Sunday Snow Level
5000'
Sunday Night Snow Level
4500'
Northwest Cascades
Date Elevation
Saturday Afternoon Snow Level
5000'
Saturday Night Snow Level
4500'
Sunday Snow Level
5000'
Sunday Night Snow Level
4500'
Northeast Cascades
Date Elevation
Saturday Afternoon Snow Level
5500'
Saturday Night Snow Level
4500'
Sunday Snow Level
5500'
Sunday Night Snow Level
4500'
Central Cascades
Date Elevation
Saturday Afternoon Snow Level
5000'
Saturday Night Snow Level
4500'
Sunday Snow Level
5000'
Sunday Night Snow Level
4500'
South Cascades
Date Elevation
Saturday Afternoon Snow Level
5500'
Saturday Night Snow Level
5000'
Sunday Snow Level
5000'
Sunday 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 Sun Mon
Hurricane Ridge .50 lt .25
Mt Baker Ski Area .25 - .50 .25
Washington Pass .25 - .50 lt .10
Stevens Pass .25 .25
Snoqualmie Pass .25 .25
Mission Ridge lt .10 lt .10
Crystal Mt lt .25 lt .25
Paradise .25 .25
White Pass lt .25 lt .25
Mt Hood Meadows .25 .25

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

Date Direction - Speed
Saturday Afternoon W 5 - 15
Saturday Night W 5 - 15
Sunday W 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
Saturday Afternoon WSW 0 - 10 SSW 0 - 10 W 10 - 20 W 10 - 20
Saturday Night W 5 - 15 W 0 - 10 W 10 - 20 WNW 10 - 20
Sunday SW 5 - 15 SW 5 - 15 W 10 - 20 W 10 - 20
Olympics
Date Elevation
Saturday Afternoon WSW 0 - 10
Saturday Night W 5 - 15
Sunday SW 5 - 15
Sunday Night E 0 - 10
Northwest Cascades
Date Elevation
Saturday Afternoon SSW 0 - 10
Saturday Night W 0 - 10
Sunday SW 5 - 15
Sunday Night W 0 - 10
Central Cascades
Date Elevation
Saturday Afternoon W 10 - 20
Saturday Night W 10 - 20
Sunday W 10 - 20
Sunday Night W 10 - 20
South Cascades
Date Elevation
Saturday Afternoon W 10 - 20
Saturday Night WNW 10 - 20
Sunday W 10 - 20
Sunday Night WNW 10 - 20
Olympics
Date Direction - Speed
Saturday Afternoon WSW 0 - 10
Saturday Night W 5 - 15
Sunday SW 5 - 15
Sunday Night E 0 - 10
Northwest Cascades
Date Direction - Speed
Saturday Afternoon SSW 0 - 10
Saturday Night W 0 - 10
Sunday SW 5 - 15
Sunday Night W 0 - 10
Central Cascades
Date Direction - Speed
Saturday Afternoon W 10 - 20
Saturday Night W 10 - 20
Sunday W 10 - 20
Sunday Night W 10 - 20
South Cascades
Date Direction - Speed
Saturday Afternoon W 10 - 20
Saturday Night WNW 10 - 20
Sunday W 10 - 20
Sunday Night WNW 10 - 20

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
Saturday Afternoon SSE 5 - 10 SE 5 - 10 W 10 - 20 W 10 - 20
Saturday Night WNW 5 - 15 SSW 5 - 15 W 15 - 25 W 5 - 15
Sunday WNW 5 - 15 NW 5 - 15 W 10 - 15 W 10 - 15
Northwest Cascades
Date Direction - Speed
Saturday Afternoon SSE 5 - 10
Saturday Night WNW 5 - 15
Sunday WNW 5 - 15
Sunday Night NNW 0 - 10
Northeast Cascades
Date Direction - Speed
Saturday Afternoon SE 5 - 10
Saturday Night SSW 5 - 15
Sunday NW 5 - 15
Sunday Night NNW 0 - 10
Central Cascades
Date Direction - Speed
Saturday Afternoon W 10 - 20
Saturday Night W 15 - 25
Sunday W 10 - 15
Sunday Night NW 0 - 10
South Cascades
Date Direction - Speed
Saturday Afternoon W 10 - 20
Saturday Night W 5 - 15
Sunday W 10 - 15
Sunday Night NW 0 - 10

Extended Weather Synopsis for Monday through Wednesday

A weak trough of low pressure should pass southward offshore Monday to maintain a chance of light showers, mainly early Monday.

High pressure should begin building offshore later Monday to allow for gradual warming and clearing.

Upper level high pressure is expected to build offshore Tuesday and shift inland across B.C. late Tuesday. The ridge of high pressure gains strength Wednesday and builds inland. This should usher a return to clearing and warming beginning Tuesday and continuing Wednesday with freezing levels climbing near or above 10,000 ft by Wednesday.

Extended Weather Forecast for Monday through Wednesday

Olympics, Washington Cascades and Mt. Hood Area
Date Weather
Monday Light rain and snow showers early. Decreasing showers with partial clearing Monday afternoon. Becoming mostly clear overnight.
Tuesday Becoming mostly sunny and warmer. Clear and mild overnight.

Snow/Freezing Levels

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Monday Snow Level 4000' - 5500' 4000' - 5500' 4000' - 5500' 4000' - 5500' 4000' - 5500'
Monday Night Freezing Level 6000' - 7000' 5000' - 6000' 5000' - 6000' 5000' - 6000' 5000' - 6000'
Tuesday Freezing Level 7000' - 9000' 6000' - 7000' 5000' - 7000' 5500' - 7500' 6000' - 8000'
Tuesday Night Freezing Level 9000' - 10500' 8000' - 9000' 8000' - 9000' 8000' - 9000' 8000' - 9000'
Olympics
Date Elevation
Monday Snow Level
4000' - 5500'
Monday Night Freezing Level
6000' - 7000'
Tuesday Freezing Level
7000' - 9000'
Tuesday Night Freezing Level
9000' - 10500'
Wednesday Freezing Level
10000' - 11000'
Northwest Cascades
Date Elevation
Monday Snow Level
4000' - 5500'
Monday Night Freezing Level
5000' - 6000'
Tuesday Freezing Level
6000' - 7000'
Tuesday Night Freezing Level
8000' - 9000'
Wednesday Freezing Level
9500' - 10500'
Northeast Cascades
Date Elevation
Monday Snow Level
4000' - 5500'
Monday Night Freezing Level
5000' - 6000'
Tuesday Freezing Level
5000' - 7000'
Tuesday Night Freezing Level
8000' - 9000'
Wednesday Freezing Level
9500' - 10500'
Central Cascades
Date Elevation
Monday Snow Level
4000' - 5500'
Monday Night Freezing Level
5000' - 6000'
Tuesday Freezing Level
5500' - 7500'
Tuesday Night Freezing Level
8000' - 9000'
Wednesday Freezing Level
10000' - 11000'
South Cascades
Date Elevation
Monday Snow Level
4000' - 5500'
Monday Night Freezing Level
5000' - 6000'
Tuesday Freezing Level
6000' - 8000'
Tuesday Night Freezing Level
8000' - 9000'
Wednesday Freezing Level
10000' - 11000'

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.