menu

Mountain Weather Forecast

Issued: 1:34 PM PST Sunday, December 31, 2017
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 Sunday & Monday

An upper level ridge of high pressure continues to build northward along the coast of the PNW Sunday. This is providing mostly sunny and warming conditions by Sunday afternoon under weakening NW flow aloft.

Building surface high pressure east of the Cascades has shifted the low level winds to easterly across the Cascade Passes and Cascade crest. This is resulting in cool temperatures and low clouds and areas of fog in some low elevation east slope areas and passes.

Little change is expected for New Years Day with areas away from the passes expecting more sunshine and further warming, while the low clouds and areas of fog persist in the passes and some lower elevation east slope areas .  

Weather forecast for Sunday & Monday

Olympics
Date Weather
Sunday Afternoon Mostly sunny with a warming trend. Light winds.
Sunday Night Mostly clear. Light winds.
Monday Mostly sunny, mild. Light winds.
Mostly clear and mild.
Washington Cascades near and west of the Crest including Stevens, Snoqualmie and White Passes
Date Weather
Sunday Afternoon Mostly sunny with a warming trend volcanoes and higher elevations. Remaining cool in the passes with low clouds and areas of fog.
Sunday Night Mostly clear and mild higher elevations. Cool with areas of low clouds and fog lower elevations and passes.
Monday Mostly sunny and mild over the volcanoes and higher elevations. Remaining cool in the passes with low clouds and areas of fog.
Mostly clear and mild higher elevations. Cool with areas of low clouds and fog lower elevations and passes.
East Slopes of the Washington Cascades
Date Weather
Sunday Afternoon Mostly sunny with a warming trend higher elevations. Remaining cool lower elevations with areas of low clouds or fog. Light winds.
Sunday Night Becoming mostly clear higher terrain. Cool with areas of low clouds and fog lower elevations.
Monday Mostly sunny and mild higher elevations. Cool lower elevations with areas of low clouds or fog. Light winds.
Mostly clear.
Mt. Hood
Date Weather
Sunday Afternoon Sunny with a warming trend. Light winds.
Sunday Night Mostly clear and mild. Light winds.
Monday Mostly sunny and mild. Light winds.
Mostly clear.

Snow Level/Freezing Level in feet

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Sunday Afternoon Freezing Level 8000' 5000' 3000' 7000' 8500' *
Sunday Night Freezing Level 8000' 6000' 4000' 7000' 8500' *
Monday Morning Freezing Level 9000' 6000' 5500' 8500' 9000' *
Monday Afternoon Freezing Level 9000' 7000' 6500' 8500' 9000' *
Olympics
Date Elevation
Sunday Afternoon Freezing Level
8000'
Easterly Flow*
Sunday Night Freezing Level
8000'
Easterly Flow*
Monday Morning Freezing Level
9000'
Easterly Flow*
Monday Afternoon Freezing Level
9000'
Easterly Flow*
Monday Night Freezing Level
9000'
Easterly Flow*
Northwest Cascades
Date Elevation
Sunday Afternoon Freezing Level
5000'
Easterly Flow*
Sunday Night Freezing Level
6000'
Easterly Flow*
Monday Morning Freezing Level
6000'
Easterly Flow*
Monday Afternoon Freezing Level
7000'
Easterly Flow*
Monday Night Freezing Level
7000'
Easterly Flow*
Northeast Cascades
Date Elevation
Sunday Afternoon Freezing Level
3000'
Easterly Flow*
Sunday Night Freezing Level
4000'
Easterly Flow*
Monday Morning Freezing Level
5500'
Easterly Flow*
Monday Afternoon Freezing Level
6500'
Easterly Flow*
Monday Night Freezing Level
6500'
Easterly Flow*
Central Cascades
Date Elevation
Sunday Afternoon Freezing Level
7000'
Easterly Flow*
Sunday Night Freezing Level
7000'
Easterly Flow*
Monday Morning Freezing Level
8500'
Easterly Flow*
Monday Afternoon Freezing Level
8500'
Easterly Flow*
Monday Night Freezing Level
8000'
Easterly Flow*
South Cascades
Date Elevation
Sunday Afternoon Freezing Level
8500'
Easterly Flow*
Sunday Night Freezing Level
8500'
Easterly Flow*
Monday Morning Freezing Level
9000'
Easterly Flow*
Monday Afternoon Freezing Level
9000'
Easterly Flow*
Monday Night Freezing Level
9000'
Easterly Flow*

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 Mon Tue
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
Sunday Afternoon E 15 - 25
Sunday Night E 10 - 20
Monday Morning E 5 - 15
Monday Afternoon E 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
Sunday Afternoon E 0 - 10 SE 0 - 10 ESE 15 - 25 ESE 5 - 10
Sunday Night VAR 0 - 10 VAR 0 - 10 ESE 0 - 10 SW 0 - 10
Monday Morning W 0 - 10 W 0 - 10 E 0 - 10 W 0 - 10
Monday Afternoon E 0 - 10 W 0 - 10 E 0 - 10 W 0 - 10
Olympics
Date Elevation
Sunday Afternoon E 0 - 10
Sunday Night VAR 0 - 10
Monday Morning W 0 - 10
Monday Afternoon E 0 - 10
Monday Night E 0 - 10
Northwest Cascades
Date Elevation
Sunday Afternoon SE 0 - 10
Sunday Night VAR 0 - 10
Monday Morning W 0 - 10
Monday Afternoon W 0 - 10
Monday Night E 0 - 10
Central Cascades
Date Elevation
Sunday Afternoon ESE 15 - 25
Sunday Night ESE 0 - 10
Monday Morning E 0 - 10
Monday Afternoon E 0 - 10
Monday Night E 0 - 10
South Cascades
Date Elevation
Sunday Afternoon ESE 5 - 10
Sunday Night SW 0 - 10
Monday Morning W 0 - 10
Monday Afternoon W 0 - 10
Monday Night ESE 0 - 10
Olympics
Date Direction - Speed
Sunday Afternoon E 0 - 10
Sunday Night VAR 0 - 10
Monday Morning W 0 - 10
Monday Afternoon E 0 - 10
Monday Night E 0 - 10
Northwest Cascades
Date Direction - Speed
Sunday Afternoon SE 0 - 10
Sunday Night VAR 0 - 10
Monday Morning W 0 - 10
Monday Afternoon W 0 - 10
Monday Night E 0 - 10
Central Cascades
Date Direction - Speed
Sunday Afternoon ESE 15 - 25
Sunday Night ESE 0 - 10
Monday Morning E 0 - 10
Monday Afternoon E 0 - 10
Monday Night E 0 - 10
South Cascades
Date Direction - Speed
Sunday Afternoon ESE 5 - 10
Sunday Night SW 0 - 10
Monday Morning W 0 - 10
Monday Afternoon W 0 - 10
Monday Night ESE 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
Sunday Afternoon NW 10 - 20 NW 10 - 20 NW 5 - 15 NW 5 - 15
Sunday Night NW 15 - 25 NW 15 - 25 NW 10 - 20 WNW 10 - 20
Monday Morning NW 10 - 20 NW 10 - 20 NW 10 - 20 WNW 5 - 15
Monday Afternoon NW 10 - 15 NW 10 - 15 NW 5 - 10 NW 5 - 10
Northwest Cascades
Date Direction - Speed
Sunday Afternoon NW 10 - 20
Sunday Night NW 15 - 25
Monday Morning NW 10 - 20
Monday Afternoon NW 10 - 15
Monday Night WNW 0 - 10
Northeast Cascades
Date Direction - Speed
Sunday Afternoon NW 10 - 20
Sunday Night NW 15 - 25
Monday Morning NW 10 - 20
Monday Afternoon NW 10 - 15
Monday Night WNW 0 - 10
Central Cascades
Date Direction - Speed
Sunday Afternoon NW 5 - 15
Sunday Night NW 10 - 20
Monday Morning NW 10 - 20
Monday Afternoon NW 5 - 10
Monday Night WNW 0 - 10
South Cascades
Date Direction - Speed
Sunday Afternoon NW 5 - 15
Sunday Night WNW 10 - 20
Monday Morning WNW 5 - 15
Monday Afternoon NW 5 - 10
Monday Night WSW 0 - 10

Extended Weather Synopsis for Tuesday through Thursday

The upper ridge will persist and gradually move inland Tuesday and Wednesday. This should maintain mostly fair weather with light winds over the region.

Offshore low level flow should maintain cooler weather with possible fog in the lower Cascade Passes. Otherwise, freezing levels should remain relatively high with warm temperatures persisting through the extended period.

A weak disturbance off California should spread some high clouds across the area Thursday with a chance of a few light showers, mainly over the Mt Hood area Thursday. 

Extended Weather Forecast for Tuesday through Thursday

Olympics, Washington Cascades and Mt. Hood Area
Date Weather
Tuesday A mostly sunny day and clear night. Mild with light winds.
Wednesday Mostly fair with some mid and high clouds at times. Mild with light winds.

Snow/Freezing Levels

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Tuesday Freezing Level 8500' - 9500' 7500' - 9000' 6500' - 8000' 8000' - 9000' 8000' - 9000' *
Tuesday Night Freezing Level 8500' - 9500' 8000' - 9000' 6500' - 7500' 8000' - 9000' 9000' - 10000' *
Wednesday Freezing Level 8000' - 9000' 6000' - 7000' 7000' - 8000' 8000' - 9000' 8500' - 9500' *
Wednesday Night Freezing Level 8500' - 9500' 6500' - 7500' 6000' - 7000' 6500' - 8000' 7000' - 8000' *
Olympics
Date Elevation
Tuesday Freezing Level
8500' - 9500'
Easterly Flow*
Tuesday Night Freezing Level
8500' - 9500'
Easterly Flow*
Wednesday Freezing Level
8000' - 9000'
Easterly Flow*
Wednesday Night Freezing Level
8500' - 9500'
Easterly Flow*
Thursday Snow Level
6500' - 7500'
Easterly Flow*
Northwest Cascades
Date Elevation
Tuesday Freezing Level
7500' - 9000'
Easterly Flow*
Tuesday Night Freezing Level
8000' - 9000'
Easterly Flow*
Wednesday Freezing Level
6000' - 7000'
Easterly Flow*
Wednesday Night Freezing Level
6500' - 7500'
Easterly Flow*
Thursday Snow Level
6000' - 7000'
Easterly Flow*
Northeast Cascades
Date Elevation
Tuesday Freezing Level
6500' - 8000'
Easterly Flow*
Tuesday Night Freezing Level
6500' - 7500'
Easterly Flow*
Wednesday Freezing Level
7000' - 8000'
Easterly Flow*
Wednesday Night Freezing Level
6000' - 7000'
Easterly Flow*
Thursday Snow Level
5000' - 6000'
Easterly Flow*
Central Cascades
Date Elevation
Tuesday Freezing Level
8000' - 9000'
Easterly Flow*
Tuesday Night Freezing Level
8000' - 9000'
Easterly Flow*
Wednesday Freezing Level
8000' - 9000'
Easterly Flow*
Wednesday Night Freezing Level
6500' - 8000'
Easterly Flow*
Thursday Snow Level
6000' - 7000'
Easterly Flow*
South Cascades
Date Elevation
Tuesday Freezing Level
8000' - 9000'
Easterly Flow*
Tuesday Night Freezing Level
9000' - 10000'
Easterly Flow*
Wednesday Freezing Level
8500' - 9500'
Easterly Flow*
Wednesday Night Freezing Level
7000' - 8000'
Easterly Flow*
Thursday Snow Level
6000' - 7000'
Easterly Flow*

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.