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Mountain Weather Forecast

Issued: 7:22 AM PST Monday, January 1, 2018
by Dennis D'Amico

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

Happy New Year!  We have a quiet weather pattern to ring in 2018 with upper ridging offshore and light to moderate offshore flow at the surface. Freezing levels will be mild over the short term period with cooler temperatures seen along the east slopes of the Cascades and in the Cascades Passes.  Brisk W-NW winds seen at some of the higher elevation NWAC weather stations this morning will ease off during the day.  A weak front dissipating over Vancouver Island should bring some periods of high clouds today. Low clouds should hang tough along the east slopes of the Cascades and lower slopes of the Cascade Passes throughout the short term. A weak upper level disturbance cutting through the upper level ridge on Tuesday will not bring any precipitation but will produce some high/mid level cloudiness over the region. 

Weather forecast for Monday & Tuesday

Olympics
Date Weather
Monday Partly sunny and mild with periods of high clouds.
Monday Night Partly cloudy and mild with periods of high clouds.
Tuesday Mostly cloudy. Mild.
Mostly cloudy. Mild.
Washington Cascades near and west of the Crest including Stevens, Snoqualmie and White Passes
Date Weather
Monday Partly sunny with periods of high clouds west of the crest. Lower clouds and cooler temperatures Cascade Passes.
Monday Night Partly cloudy with periods of high clouds west of the crest. Lower clouds and cooler temperatures Cascade Passes.
Tuesday Mostly cloudy. Lower clouds Cascade Passes.
Mostly cloudy. Lower clouds Cascade Passes.
East Slopes of the Washington Cascades
Date Weather
Monday Partly sunny with periods of high clouds, low clouds lower slopes.
Monday Night Partly cloudy with periods of high clouds, low clouds lower slopes.
Tuesday Mostly cloudy. Low clouds lower slopes.
Mostly cloudy. Low clouds lower slopes.
Mt. Hood
Date Weather
Monday Partly sunny with periods of high clouds.
Monday Night Partly cloudy with periods of high clouds. Cooler and cloudier lower elevations exposed to easterly flow.
Tuesday Mostly cloudy. Cooler and cloudier lower elevations exposed to easterly flow.
Mostly cloudy.

Snow Level/Freezing Level in feet

Date Olympics Northwest Cascades Northeast Cascades Central Cascades South Cascades Easterly Flow in Passes
Monday Morning Snow Level 8000' 7000' 0' 6000' 9000' *
Monday Afternoon Snow Level 9000' 8000' 5000' 8000' 9000' *
Monday Night Snow Level 9500' 8000' 3000' 8500' 9000' *
Tuesday Snow Level 9500' 8500' 5000' 8500' 9000' *
Olympics
Date Elevation
Monday Morning Snow Level
8000'
Easterly Flow*
Monday Afternoon Snow Level
9000'
Easterly Flow*
Monday Night Snow Level
9500'
Easterly Flow*
Tuesday Snow Level
9500'
Easterly Flow*
Tuesday Night Snow Level
9500'
Easterly Flow*
Northwest Cascades
Date Elevation
Monday Morning Snow Level
7000'
Easterly Flow*
Monday Afternoon Snow Level
8000'
Easterly Flow*
Monday Night Snow Level
8000'
Easterly Flow*
Tuesday Snow Level
8500'
Easterly Flow*
Tuesday Night Snow Level
8500'
Easterly Flow*
Northeast Cascades
Date Elevation
Monday Morning Snow Level
0'
Easterly Flow*
Monday Afternoon Snow Level
5000'
Easterly Flow*
Monday Night Snow Level
3000'
Easterly Flow*
Tuesday Snow Level
5000'
Easterly Flow*
Tuesday Night Snow Level
3000'
Easterly Flow*
Central Cascades
Date Elevation
Monday Morning Snow Level
6000'
Easterly Flow*
Monday Afternoon Snow Level
8000'
Easterly Flow*
Monday Night Snow Level
8500'
Easterly Flow*
Tuesday Snow Level
8500'
Easterly Flow*
Tuesday Night Snow Level
8500'
Easterly Flow*
South Cascades
Date Elevation
Monday Morning Snow Level
9000'
Easterly Flow*
Monday Afternoon Snow Level
9000'
Easterly Flow*
Monday Night Snow Level
9000'
Easterly Flow*
Tuesday Snow Level
9000'
Easterly Flow*
Tuesday Night Snow 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 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 E 15 - 25
Monday Night E 15 - 25
Tuesday E 20 - 30

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 W 0 - 10 VAR 0 - 10 W 0 - 10 SW 0 - 10
Monday Afternoon VAR 0 - 10 VAR 0 - 10 VAR 0 - 10 E 0 - 10
Monday Night SE 0 - 10 ESE 0 - 10 E 0 - 10 ESE 0 - 10
Tuesday S 0 - 10 ENE 0 - 10 ESE 10 - 20 ESE 10 - 20
Olympics
Date Elevation
Monday Morning W 0 - 10
Monday Afternoon VAR 0 - 10
Monday Night SE 0 - 10
Tuesday S 0 - 10
Tuesday Night SE 0 - 10
Northwest Cascades
Date Elevation
Monday Morning VAR 0 - 10
Monday Afternoon VAR 0 - 10
Monday Night ESE 0 - 10
Tuesday ENE 0 - 10
Tuesday Night VAR 0 - 10
Central Cascades
Date Elevation
Monday Morning W 0 - 10
Monday Afternoon VAR 0 - 10
Monday Night E 0 - 10
Tuesday ESE 10 - 20
Tuesday Night E 0 - 10
South Cascades
Date Elevation
Monday Morning SW 0 - 10
Monday Afternoon E 0 - 10
Monday Night ESE 0 - 10
Tuesday ESE 10 - 20
Tuesday Night ESE 0 - 10
Olympics
Date Direction - Speed
Monday Morning W 0 - 10
Monday Afternoon VAR 0 - 10
Monday Night SE 0 - 10
Tuesday S 0 - 10
Tuesday Night SE 0 - 10
Northwest Cascades
Date Direction - Speed
Monday Morning VAR 0 - 10
Monday Afternoon VAR 0 - 10
Monday Night ESE 0 - 10
Tuesday ENE 0 - 10
Tuesday Night VAR 0 - 10
Central Cascades
Date Direction - Speed
Monday Morning W 0 - 10
Monday Afternoon VAR 0 - 10
Monday Night E 0 - 10
Tuesday ESE 10 - 20
Tuesday Night E 0 - 10
South Cascades
Date Direction - Speed
Monday Morning SW 0 - 10
Monday Afternoon E 0 - 10
Monday Night ESE 0 - 10
Tuesday ESE 10 - 20
Tuesday 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
Monday Morning NW 15 - 25 NW 15 - 25 NW 15 - 25 NW 10 - 20
Monday Afternoon NW 10 - 20 NW 5 - 15 NW 10 - 20 NW 5 - 15
Monday Night SW 0 - 10 SW 0 - 10 SW 0 - 10 SW 5 - 15
Tuesday SW 5 - 15 SW 5 - 15 SW 5 - 15 SW 10 - 20
Northwest Cascades
Date Direction - Speed
Monday Morning NW 15 - 25
Monday Afternoon NW 10 - 20
Monday Night SW 0 - 10
Tuesday SW 5 - 15
Tuesday Night W 0 - 10
Northeast Cascades
Date Direction - Speed
Monday Morning NW 15 - 25
Monday Afternoon NW 5 - 15
Monday Night SW 0 - 10
Tuesday SW 5 - 15
Tuesday Night W 0 - 10
Central Cascades
Date Direction - Speed
Monday Morning NW 15 - 25
Monday Afternoon NW 10 - 20
Monday Night SW 0 - 10
Tuesday SW 5 - 15
Tuesday Night W 5 - 15
South Cascades
Date Direction - Speed
Monday Morning NW 10 - 20
Monday Afternoon NW 5 - 15
Monday Night SW 5 - 15
Tuesday SW 10 - 20
Tuesday Night SW 10 - 20

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.

The Extended Mountain Weather Forecast (Days 3-5) will be included with the afternoon forecast issuance between 2 - 3 PM.