Issued: 5:14 PM PST Wednesday, November 15, 2017
by Dennis D'Amico

Jump to: Weather Forecast I Snow/Freezing Level I Precipitation I Free Winds 5k I Free Winds 9k I Extended Weather

Weather Synopsis for Wednesday & Thursday

The deep Pacific low pressure system that has been pounding the Pacific Northwest over the last several days will remain quasi-stationary but weaken and rotate showers through the area over the short term.  The main frontal band associated with the low pressure slid SE today, with heavier precipitation transitioning to showers from north to south over the region. An additional 5-10 inches of snow accumulated at NWAC sites in the Olympics and west slopes of the Cascades with lesser amounts for Mt. Hood and the east slopes of the Cascades through the day light hours on Wednesday. 

Showers should become somewhat invigorated on Thursday afternoon as an another trough swings through and then shower activity should become light and scattered Thursday night through Friday.  A dirty ridge will begin building over the area Friday, but plenty of moisture and the aforementioned showers should still affect the mountains. 

Weather Forecast

Olympics and Washington Cascades near and west of the Crest including Stevens, Snoqualmie and White Pass
Wednesday Afternoon - Thursday Morning

Mostly cloudy with light to occasionally moderate rain and snow showers. 

Thursday Afternoon

Cloudy with light to moderate rain and snow showers. 

East slopes of the Washington Cascades
Wednesday Afternoon - Thursday Morning

Mostly cloudy with scattered light rain and snow showers. 

Thursday Afternoon

Cloudy with light rain and snow showers, mainly near the Cascade crest. 

Mt. Hood Area
Wednesday Afternoon - Wednesday Evening

Cloudy with light to moderate rain and snow. 

Thursday Afternoon

Cloudy with light to moderate rain and snow showers. 

Thursday Night

Mostly cloudy with light rain and snow showers decreasing and becoming scattered overnight. 

Snow/Freezing Level (ft)

Hurricane Ridge Mt. Baker Washington Pass Leavenworth Stevens Pass Snoqualmie Pass Mt. Rainier, Crystal & White Pass Mt. Hood
Wednesday Afternoon Snow Level 3000' 3000' 3000' ' ' 3000' ' 4000'
Wednesday Night Snow Level 2500' 2000' 2000' ' ' 2500' ' 3000'
Thursday Snow Level 2500' 2500' 2500' ' ' 3000' ' 3500'
Hurricane Ridge Elevation
Wednesday Afternoon Snow Level
3000'
Wednesday Night Snow Level
2500'
Thursday Snow Level
2500'
Thursday Night Snow Level
2500'
Mt. Baker Elevation
Wednesday Afternoon Snow Level
3000'
Wednesday Night Snow Level
2000'
Thursday Snow Level
2500'
Thursday Night Snow Level
2000'
Washington Pass Elevation
Wednesday Afternoon Snow Level
3000'
Wednesday Night Snow Level
2000'
Thursday Snow Level
2500'
Thursday Night Snow Level
1500'
Leavenworth Elevation
Wednesday Afternoon Snow Level
'
Wednesday Night Snow Level
'
Thursday Snow Level
'
Thursday Night Snow Level
'
Stevens Pass Elevation
Wednesday Afternoon Snow Level
'
Wednesday Night Snow Level
'
Thursday Snow Level
'
Thursday Night Snow Level
'
Snoqualmie Pass Elevation
Wednesday Afternoon Snow Level
3000'
Wednesday Night Snow Level
2500'
Thursday Snow Level
3000'
Thursday Night Snow Level
2500'
Mt. Rainier & Crystal Elevation
Wednesday Afternoon Snow Level
'
Wednesday Night Snow Level
'
Thursday Snow Level
'
Thursday Night Snow Level
'
Mt. Hood Elevation
Wednesday Afternoon Snow Level
4000'
Wednesday Night Snow Level
3000'
Thursday Snow Level
3500'
Thursday Night Snow Level
2500'

* Easterly flow in the Cascade Passes can cause locally lower Snow or Freezing levels than areas further west.
Freezing Level is when no precipitation is forecast.

Precipitation Forecast

Thursday Thursday
Hurricane Ridge 0 - 0.75 LT 0.25
Mt Baker Ski Area 1.00 - 1.50 0.25 - 0.50
Washington Pass 0.25 - 0.50 LT 0.25
Stevens Pass 0.50 - 0.75 0 - 0.50
Snoqualmie Pass 1.00 - 1.50 0 - 0.50
Mission Ridge LT 0.25 LT 0.10
Crystal Mt 0 - 0.75 LT 0.25
Paradise 1.00 - 1.50 0 - 0.50
White Pass 0.50 - 0.75 0.25 - 0.50
Mt Hood Meadows 0.50 - 0.75 0.50 - 0.75
0.75 - 1.00 0.25 - 0.50

Free Winds at 5000' (mph)

Hurricane Ridge Mt. Baker Stevens to Snoqualmie Pass Mt. Rainier Mt. Hood
Wednesday Afternoon S 10 - 20 SSE 10 - 20 SSE 0 - 10 --- - WSW 5 - 15
Wednesday Night SW 0 - 10 S 0 - 10 SSW 5 - 15 --- - SW 15 - 25
Thursday SW 0 - 10 S 0 - 10 SW 0 - 10 --- - SW 10 - 20
Hurricane Ridge Elevation
Wednesday Afternoon S 10 - 20
Wednesday Night SW 0 - 10
Thursday SW 0 - 10
Thursday Night WSW 15 - 25
Mt. Baker Elevation
Wednesday Afternoon SSE 10 - 20
Wednesday Night S 0 - 10
Thursday S 0 - 10
Thursday Night SW 10 - 20
Stevens and Snoqualmie Pass Elevation
Wednesday Afternoon SSE 0 - 10
Wednesday Night SSW 5 - 15
Thursday SW 0 - 10
Thursday Night WSW 10 - 20
Mt. Rainier Elevation
Wednesday Afternoon --- -
Wednesday Night --- -
Thursday --- -
Thursday Night --- -
Mt. Hood Elevation
Wednesday Afternoon WSW 5 - 15
Wednesday Night SW 15 - 25
Thursday SW 10 - 20
Thursday Night WSW 15 - 30
Hurricane Ridge Direction - Speed
Wednesday Afternoon S 10 - 20
Wednesday Night SW 0 - 10
Thursday SW 0 - 10
Thursday Night WSW 15 - 25
Mt. Baker Direction - Speed
Wednesday Afternoon SSE 10 - 20
Wednesday Night S 0 - 10
Thursday S 0 - 10
Thursday Night SW 10 - 20
Stevens and Snoqualmie Pass Direction - Speed
Wednesday Afternoon SSE 0 - 10
Wednesday Night SSW 5 - 15
Thursday SW 0 - 10
Thursday Night WSW 10 - 20
Mt. Rainier Direction - Speed
Wednesday Afternoon --- -
Wednesday Night --- -
Thursday --- -
Thursday Night --- -
Mt. Hood Direction - Speed
Wednesday Afternoon WSW 5 - 15
Wednesday Night SW 15 - 25
Thursday SW 10 - 20
Thursday Night WSW 15 - 30

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.

Free Winds at 9000' (mph)

Mt. Baker Washington Pass Stevens to Snoqualmie Pass Mt. Rainier Mt. Hood
Wednesday Afternoon SW 20 - 30 SW 10 - 20 SW 20 - 30 --- - SW 25 - 35
Wednesday Night SW 10 - 20 SW 20 - 30 SW 20 - 30 --- - SW 30 - 40
Thursday SW 10 - 20 SW 10 - 20 SW 15 - 25 --- - SW 30 - 40
Mt. Baker Direction - Speed
Wednesday Afternoon SW 20 - 30
Wednesday Night SW 10 - 20
Thursday SW 10 - 20
Thursday Night WSW 20 - 30
Washington Pass Direction - Speed
Wednesday Afternoon SW 10 - 20
Wednesday Night SW 20 - 30
Thursday SW 10 - 20
Thursday Night WSW 25 - 35
Stevens and Snoqualmie Pass Direction - Speed
Wednesday Afternoon SW 20 - 30
Wednesday Night SW 20 - 30
Thursday SW 15 - 25
Thursday Night W 25 - 35
Mt. Rainier Direction - Speed
Wednesday Afternoon --- -
Wednesday Night --- -
Thursday --- -
Thursday Night --- -
Mt. Hood Direction - Speed
Wednesday Afternoon SW 25 - 35
Wednesday Night SW 30 - 40
Thursday SW 30 - 40
Thursday Night W 30 - 40

Extended Weather Synopsis for Thursday night through Thursday

The flat upper ridge axis should shift slightly east and build somewhat more on Saturday. There may be some light periods of rain and snow for the Olympics and Mt. Baker, with generally cloudy conditions further south and east. Depending on how much the ridge builds Saturday, clearer skies may pan out for Mt. Hood and the south Washington Cascades. 

A vigorous frontal system will drop down from the NE Pacific on Sunday. Current forecast models agree that heavier precipitation will begin for the northwest Cascades including Mt. Baker and Olympics by mid-day Sunday and generally hold off during the daylight hours for the south Washington Cascades and Mt. Hood. A slight warming trend during the day on Sunday will precede the frontal passage.  

Extended Weather

Olympics, Washington Cascades and Mt. Hood Area
Friday - Friday Night

Cloudy with scattered light rain and snow showers. 

Saturday - Saturday Night

Cloudy with periods of light rain and snow Olympics and northwest Cascades including Mt. Baker. Cloudy rest of Washington Cascades. Partly to mostly cloudy Mt. Hood. 

Sunday

Rain and snow developing late morning Olympics and northwest Cascades including Mt. Baker, becoming stormy in the afternoon.  Light rain and snow developing Sunday afternoon for the south and central Washington Cascades. Mostly cloudy Mt. Hood.  

Extended Snow/Freezing Levels

Mt. Baker Snoqualmie Pass Mt. Hood Easterly Flow *
Friday - Friday Night Snow Level 2000' - 3000' 2500' - 3500' 3000' - 4000'
Saturday Snow Level 2500' - 3500' 3000' - 4000' 4000' - 5000'
Saturday Night Snow Level 2000' - 3000' 3000' - 4000' 4000' - 5000' *
Mt. Baker Elevation
Friday - Friday Night Snow Level
2000' - 3000'
Saturday Snow Level
2500' - 3500'
Saturday Night Snow Level
2000' - 3000'
(Easterly Flow *)
Sunday Snow Level
3000' - 4000'
(Easterly Flow *)
Snoqualmie Pass Elevation
Friday - Friday Night Snow Level
2500' - 3500'
Saturday Snow Level
3000' - 4000'
Saturday Night Snow Level
3000' - 4000'
(Easterly Flow *)
Sunday Snow Level
4000' - 5000'
(Easterly Flow *)
Mt. Hood Elevation
Friday - Friday Night Snow Level
3000' - 4000'
Saturday Snow Level
4000' - 5000'
Saturday Night Snow Level
4000' - 5000'
(Easterly Flow *)
Sunday Snow Level
5500' - 6500'
(Easterly Flow *)

* Easterly flow in the Cascade Passes can cause locally lower Snow or Freezing levels than areas further west.
Freezing Level is when no precipitation is forecast.

Jump to: Weather Forecast I Snow/Freezing Level I Precipitation I Free Winds 5k I Free Winds 9k I Extended Weather

Previous forecast from May 15, 2017

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.