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Mountain Weather Forecast

Issued: 3:15 PM Wednesday, April 1, 2015
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 Wednesday & Thursday

Cool and showery westerly flow behind a frontal passage Tuesday continues early Wednesday. A strong convergence pattern overnight and early Wednesday have been focused on Snoqualmie Pass, which won the new snow prize for the season! The study plots at Alpental and Snoqualmie WSDOT received 18 and 15 inches of 24 hour new snow respectively as of Wednesday morning. Showers should continue Wednesday along the west slopes and increase during the afternoon as an upper trough crossing the region combines with daytime warming. This pattern should maintain the chance of afternoon and evening thunderstorms as well.

Showers should diminish overnight Wednesday as high pressure begins rebuilding off the coast. A ridge of upper level high pressure should strengthen Thursday and gradually shift inland later Thursday. This should limit the chance of showers and provide sun breaks or even mostly sunny conditions in places Thursday. 

Weather forecast for Wednesday & Thursday

Olympics, Washington Cascades near and west of the crest including Stevens, Snoqualmie, and White Passes and Mt. Hood area
Date Weather
Wednesday Afternoon - Wednesday Evening

Mostly cloudy with light to moderate rain and snow showers, heaviest vicinity of Snoqualmie Pass to Mt Hood. Chance of thunderstorms afternoon and evening.  

Wednesday Night - Thursday Morning

Mostly cloudy with isolated light rain and snow showers. 

East slopes of the Washington Cascades
Date Weather
Wednesday Afternoon - Wednesday Evening

Partly to mostly cloudy with increasing light rain and snow showers. Chance of thunderstorms afternoon and evening near the Cascade crest.  

Wednesday Night - Thursday Morning

Partly cloudy with isolated light rain and snow showers. 

Snow Level/Freezing Level in feet

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Wednesday Afternoon Snow Level 3500' 3000' 3500' 3000' 3500'
Wednesday Night - Thursday Morning Snow Level 2500' 2000' 2500' 2500' 2500'
Olympics
Date Elevation
Wednesday Afternoon Snow Level
3500'
Wednesday Night - Thursday Morning Snow Level
2500'
Thursday Afternoon - Thursday Night Snow Level
3500'
Northwest Cascades
Date Elevation
Wednesday Afternoon Snow Level
3000'
Wednesday Night - Thursday Morning Snow Level
2000'
Thursday Afternoon - Thursday Night Snow Level
3000'
Northeast Cascades
Date Elevation
Wednesday Afternoon Snow Level
3500'
Wednesday Night - Thursday Morning Snow Level
2500'
Thursday Afternoon - Thursday Night Snow Level
3500'
Central Cascades
Date Elevation
Wednesday Afternoon Snow Level
3000'
Wednesday Night - Thursday Morning Snow Level
2500'
Thursday Afternoon - Thursday Night Snow Level
3500'
South Cascades
Date Elevation
Wednesday Afternoon Snow Level
3500'
Wednesday Night - Thursday Morning Snow Level
2500'
Thursday Afternoon - Thursday Night Snow 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 Thu Fri
Hurricane Ridge lt .25 lt .10
Mt Baker Ski Area .25 lt .10
Washington Pass lt .10 lt .10
Stevens Pass .25 - .50 lt .10
Snoqualmie Pass .75 lt .10
Mission Ridge lt .10 lt .10
Crystal Mt lt .25 lt .10
Paradise .25 lt .10
White Pass .25 lt .10
Mt Hood Meadows .50 lt .10

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

Date Direction - Speed
Wednesday Afternoon W 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
Wednesday Afternoon - Thursday Morning NW 10 - 20 W 5 - 15 WNW 10 - 20 WNW 10 - 20
Olympics
Date Elevation
Wednesday Afternoon - Thursday Morning NW 10 - 20
Thursday Afternoon - Thursday Night SW 5 - 15
Northwest Cascades
Date Elevation
Wednesday Afternoon - Thursday Morning W 5 - 15
Thursday Afternoon - Thursday Night SW 5 - 15
Central Cascades
Date Elevation
Wednesday Afternoon - Thursday Morning WNW 10 - 20
Thursday Afternoon - Thursday Night W 5 - 15
South Cascades
Date Elevation
Wednesday Afternoon - Thursday Morning WNW 10 - 20
Thursday Afternoon - Thursday Night W 5 - 15
Olympics
Date Direction - Speed
Wednesday Afternoon - Thursday Morning NW 10 - 20
Thursday Afternoon - Thursday Night SW 5 - 15
Northwest Cascades
Date Direction - Speed
Wednesday Afternoon - Thursday Morning W 5 - 15
Thursday Afternoon - Thursday Night SW 5 - 15
Central Cascades
Date Direction - Speed
Wednesday Afternoon - Thursday Morning WNW 10 - 20
Thursday Afternoon - Thursday Night W 5 - 15
South Cascades
Date Direction - Speed
Wednesday Afternoon - Thursday Morning WNW 10 - 20
Thursday Afternoon - Thursday Night W 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
Wednesday Afternoon - Thursday Morning NW 10 - 20 NW 10 - 20 NW 15 - 25 NW 20 - 30
Northwest Cascades
Date Direction - Speed
Wednesday Afternoon - Thursday Morning NW 10 - 20
Thursday Afternoon - Thursday Night W 5 - 15
Northeast Cascades
Date Direction - Speed
Wednesday Afternoon - Thursday Morning NW 10 - 20
Thursday Afternoon - Thursday Night W 5 - 15
Central Cascades
Date Direction - Speed
Wednesday Afternoon - Thursday Morning NW 15 - 25
Thursday Afternoon - Thursday Night W 10 - 20
South Cascades
Date Direction - Speed
Wednesday Afternoon - Thursday Morning NW 20 - 30
Thursday Afternoon - Thursday Night WNW 10 - 20

Extended Weather Synopsis for Friday through Sunday

The next expected front has slowed, in the most recent forecast models, and is now expected to pass the area during the day Friday. This should spread high and mid clouds over the Olympics and the north Cascades Thursday night with light precipitation reaching the Olympics early Friday. Light rain and snow should develop over the entire area by mid morning, Friday with a weak N-S oriented front passing through sometime in the afternoon or evening. A cold upper level low will settle in over the region over the weekend leading to low snow levels, a mix of sun and clouds and generally light showers.

Extended Weather Forecast for Friday through Sunday

Olympics, Washington Cascades near and west of the crest including Stevens, Snoqualmie, and White Passes and Mt. Hood Area
Date Weather
Friday - Friday Mid-day

Light rain and snow developing Olympics and North Cascades and spreading south Friday morning spreading to the remainder of the Cascades midday.. 

Friday Afternoon - Friday Night

Mostly cloudy with light to occasionally moderate rain and snow showers Olympics, west slopes of the Cascades and Mt. Hood area. Partly to mostly cloudy with scattered light rain and snow showers east slopes of the Cascades. 

Snow/Freezing Levels

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Olympics
Date Elevation
Friday - Sunday Snow Level
2500' - 3500'
Northwest Cascades
Date Elevation
Friday - Sunday Snow Level
2500' - 3500'
Northeast Cascades
Date Elevation
Friday - Sunday Snow Level
2500' - 3500'
Central Cascades
Date Elevation
Friday - Sunday Snow Level
2500' - 3500'
South Cascades
Date Elevation
Friday - Sunday Snow Level
3000' - 4000'

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.