Issued: 2:03 PM PST Tuesday, December 17, 2013
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 Tuesday & Monday

Light precipitation is beginning over the North Cascades and Olympics this afternoon with zonal flow aloft and with a weak frontal system draped over the area.  The front will slowly sag south tonight, and clouds and light precipitation should hold off for Mt. Hood until Wednesday morning.  Alpine winds should be moderately strong out of the W or WNW through mid-day Wednesday with slowly increasing clouds late today.  Light showers should persist along the west slopes tonight.  

A shortwave trough will quickly follow on Wednesday, passing through western Washington in the afternoon.  This should deliver a quick shot of light to occasionally moderate showers along with a substantial cooling trend through the day.  Again, precipitation totals are on the lighter side.  Some added convergence may add some additional light accumulations from Snoqualmie Pass and south with the NW flow Wednesday evening. Showers should diminish overnight and give way to a clearing trend as the shortwave energy splits and the flow aloft becomes northerly Wednesday night. 

Weather Forecast

Olympics, Washington Cascades near and west of the crest including Stevens, Snoqualmie, and White Passes
Tuesday Afternoon - Tuesday Evening

Mostly cloudy with light rain and snow developing North Cascades and Olympics in the afternoon and spreading south.

Tuesday Night - Wednesday Morning

Light rain and snow showers.  

Wednesday Afternoon - Wednesday Evening

Light to occasionally moderate rain and snow showers.  Sharp cooling trend. 

East slopes of the Washington Cascades
Tuesday Afternoon - Tuesday Evening

Mostly cloudy with light rain and snow flurries developing Northeast Cascades in the early afternoon and spreading south.

Tuesday Night - Wednesday Morning

Light rain and snow showers mainly near the Cascade crest.  

Wednesday Afternoon - Wednesday Evening

Light to occasionally moderate rain and snow showers near the Cascade crest.  Sharp cooling trend. 

Mt. Hood Area
Tuesday - Wednesday Morning

Partly cloudy and mild with increasing clouds overnight, chance of light snow by Wednesday morning. 

Wednesday Afternoon - Wednesday Evening

Mostly cloudy with light rain and snow showers.  Becoming colder during the day.  

Snow/Freezing Level (ft)

Hurricane Ridge Mt. Baker Washington Pass Leavenworth Stevens Pass Snoqualmie Pass Mt. Rainier, Crystal & White Pass Mt. Hood
Tuesday Afternoon Snow Level 5000' ' ' ' ' 5500' ' 8000'
Tuesday Evening Snow Level 4000' ' ' ' ' 4500' ' 6500'
Tuesday Night - Wednesday Morning Snow Level 2500' ' ' ' ' 3500' ' 5000'
Wednesday Afternoon - Wednesday Evening Snow Level 1500' ' ' ' ' 1500' ' 2000'
Hurricane Ridge Elevation
Tuesday Afternoon Snow Level
5000'
Tuesday Evening Snow Level
4000'
Tuesday Night - Wednesday Morning Snow Level
2500'
Wednesday Afternoon - Wednesday Evening Snow Level
1500'
Wednesday Night Freezing Level
500'
Mt. Baker Elevation
Tuesday Afternoon Snow Level
'
Tuesday Evening Snow Level
'
Tuesday Night - Wednesday Morning Snow Level
'
Wednesday Afternoon - Wednesday Evening Snow Level
'
Wednesday Night Freezing Level
'
Washington Pass Elevation
Tuesday Afternoon Snow Level
'
Tuesday Evening Snow Level
'
Tuesday Night - Wednesday Morning Snow Level
'
Wednesday Afternoon - Wednesday Evening Snow Level
'
Wednesday Night Freezing Level
'
Leavenworth Elevation
Tuesday Afternoon Snow Level
'
Tuesday Evening Snow Level
'
Tuesday Night - Wednesday Morning Snow Level
'
Wednesday Afternoon - Wednesday Evening Snow Level
'
Wednesday Night Freezing Level
'
Stevens Pass Elevation
Tuesday Afternoon Snow Level
'
Tuesday Evening Snow Level
'
Tuesday Night - Wednesday Morning Snow Level
'
Wednesday Afternoon - Wednesday Evening Snow Level
'
Wednesday Night Freezing Level
'
Snoqualmie Pass Elevation
Tuesday Afternoon Snow Level
5500'
Tuesday Evening Snow Level
4500'
Tuesday Night - Wednesday Morning Snow Level
3500'
Wednesday Afternoon - Wednesday Evening Snow Level
1500'
Wednesday Night Freezing Level
500'
Mt. Rainier & Crystal Elevation
Tuesday Afternoon Snow Level
'
Tuesday Evening Snow Level
'
Tuesday Night - Wednesday Morning Snow Level
'
Wednesday Afternoon - Wednesday Evening Snow Level
'
Wednesday Night Freezing Level
'
Mt. Hood Elevation
Tuesday Afternoon Snow Level
8000'
Tuesday Evening Snow Level
6500'
Tuesday Night - Wednesday Morning Snow Level
5000'
Wednesday Afternoon - Wednesday Evening Snow Level
2000'
Wednesday Night Freezing Level
1000'

* 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

Monday Monday
Hurricane Ridge LT 0.10 LT 0.10
Mt Baker Ski Area 0.25 - 0.50 LT 0.25
Washington Pass LT 0.10 LT 0.10
Stevens Pass LT 0.25 LT 0.25
Snoqualmie Pass LT 0.25 LT 0.25
Mission Ridge LT 0.10 LT 0.10
Crystal Mt LT 0.10 LT 0.25
Paradise LT 0.10 LT 0.25
White Pass LT 0.10 LT 0.10
Mt Hood Meadows LT 0.10 LT 0.10
LT 0.10 LT 0.25

Free Winds at 5000' (mph)

Hurricane Ridge Mt. Baker Stevens to Snoqualmie Pass Mt. Rainier Mt. Hood
Tuesday Afternoon - Tuesday Evening WSW 15 - 25 --- - W 10 - 20 --- - W 10 - 20
Tuesday Night - Wednesday Morning WNW 15 - 25 --- - W 10 - 20 --- - W 10 - 20
Wednesday Afternoon NW 10 - 20 --- - W 0 - 10 --- - W 0 - 10
Hurricane Ridge Elevation
Tuesday Afternoon - Tuesday Evening WSW 15 - 25
Tuesday Night - Wednesday Morning WNW 15 - 25
Wednesday Afternoon NW 10 - 20
Wednesday Night N 5 - 15
Mt. Baker Elevation
Tuesday Afternoon - Tuesday Evening --- -
Tuesday Night - Wednesday Morning --- -
Wednesday Afternoon --- -
Wednesday Night --- -
Stevens and Snoqualmie Pass Elevation
Tuesday Afternoon - Tuesday Evening W 10 - 20
Tuesday Night - Wednesday Morning W 10 - 20
Wednesday Afternoon W 0 - 10
Wednesday Night N 0 - 10
Mt. Rainier Elevation
Tuesday Afternoon - Tuesday Evening --- -
Tuesday Night - Wednesday Morning --- -
Wednesday Afternoon --- -
Wednesday Night --- -
Mt. Hood Elevation
Tuesday Afternoon - Tuesday Evening W 10 - 20
Tuesday Night - Wednesday Morning W 10 - 20
Wednesday Afternoon W 0 - 10
Wednesday Night N 0 - 10
Hurricane Ridge Direction - Speed
Tuesday Afternoon - Tuesday Evening WSW 15 - 25
Tuesday Night - Wednesday Morning WNW 15 - 25
Wednesday Afternoon NW 10 - 20
Wednesday Night N 5 - 15
Mt. Baker Direction - Speed
Tuesday Afternoon - Tuesday Evening --- -
Tuesday Night - Wednesday Morning --- -
Wednesday Afternoon --- -
Wednesday Night --- -
Stevens and Snoqualmie Pass Direction - Speed
Tuesday Afternoon - Tuesday Evening W 10 - 20
Tuesday Night - Wednesday Morning W 10 - 20
Wednesday Afternoon W 0 - 10
Wednesday Night N 0 - 10
Mt. Rainier Direction - Speed
Tuesday Afternoon - Tuesday Evening --- -
Tuesday Night - Wednesday Morning --- -
Wednesday Afternoon --- -
Wednesday Night --- -
Mt. Hood Direction - Speed
Tuesday Afternoon - Tuesday Evening W 10 - 20
Tuesday Night - Wednesday Morning W 10 - 20
Wednesday Afternoon W 0 - 10
Wednesday Night N 0 - 10

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
Tuesday Afternoon - Tuesday Evening --- - --- - W 30 - 45 --- - W 30 - 40
Wednesday Morning --- - --- - NW 20 - 35 --- - WNW 25 - 40
Wednesday Afternoon --- - --- - W 15 - 25 --- - NW 25 - 35
Mt. Baker Direction - Speed
Tuesday Afternoon - Tuesday Evening --- -
Wednesday Morning --- -
Wednesday Afternoon --- -
Wednesday Night --- -
Washington Pass Direction - Speed
Tuesday Afternoon - Tuesday Evening --- -
Wednesday Morning --- -
Wednesday Afternoon --- -
Wednesday Night --- -
Stevens and Snoqualmie Pass Direction - Speed
Tuesday Afternoon - Tuesday Evening W 30 - 45
Wednesday Morning NW 20 - 35
Wednesday Afternoon W 15 - 25
Wednesday Night N 15 - 25
Mt. Rainier Direction - Speed
Tuesday Afternoon - Tuesday Evening --- -
Wednesday Morning --- -
Wednesday Afternoon --- -
Wednesday Night --- -
Mt. Hood Direction - Speed
Tuesday Afternoon - Tuesday Evening W 30 - 40
Wednesday Morning WNW 25 - 40
Wednesday Afternoon NW 25 - 35
Wednesday Night NNE 10 - 20

Extended Weather Synopsis for Monday night through Monday

Northerly flow aloft and surface high pressure in southern British Columbia will help deliver a cold and dry air mass to the area on Thursday.  This pattern should be short lived though as increasing clouds stream in from the northwest Thursday afternoon, a precursor to incoming storm system.    

Snow levels should start out quite low as warm frontal precipitation spreads from the Olympics and North Cascades south during the day on Friday. However, strong high pressure out near 140 W will continue to inch eastward, and keep Washington/Oregon on the warm side of the jet stream.  Snow levels should rise quickly during the day on Friday, except in the passes where easterly flow should initially keep the precipitation as now until some point late in the day.  The warming trend will be accompanied by strong NW winds in the alpine through Friday night along with moderate to heavy precipitation. Showers should ease on Saturday but it should remain mild. 

Extended Weather

Washington Cascades and Mt. Hood area
Thursday - Friday Morning

Cold and dry.  Increasing clouds beginning in the afternoon and continuing overnight.   Light snow possible North Cascades and Olympics early Friday morning. 

Friday Afternoon - Friday Night

Increasing moderate to occasionally heavy rain and snow for west slopes turning to showers overnight.   Strong warming trend with locally lower snow levels in the Cascade passes initially.  

Saturday

Light rain and snow showers, occasionally moderate west slopes.  

Extended Snow/Freezing Levels

Mt. Baker Snoqualmie Pass Mt. Hood Easterly Flow *
Thursday - Friday Morning Freezing Level ' - ' 500' - 1500' 1000' - 2000'
Friday Afternoon Snow Level ' - ' 3500' - 4500' 6500' - 7500' *
Mt. Baker Elevation
Thursday - Friday Morning Freezing Level
' - '
Friday Afternoon Snow Level
' - '
(Easterly Flow *)
Friday Night - Saturday Snow Level
' - '
Snoqualmie Pass Elevation
Thursday - Friday Morning Freezing Level
500' - 1500'
Friday Afternoon Snow Level
3500' - 4500'
(Easterly Flow *)
Friday Night - Saturday Snow Level
4000' - 6000'
Mt. Hood Elevation
Thursday - Friday Morning Freezing Level
1000' - 2000'
Friday Afternoon Snow Level
6500' - 7500'
(Easterly Flow *)
Friday Night - Saturday Snow Level
5500' - 7500'

* 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 Dec 17, 2013

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