Issued: 8:21 AM PST Monday, December 29, 2014
by Dennis D'Amico

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Weather Synopsis for Monday & Sunday

Light to moderate snowfall in the Mt. Hood area and along the east slopes of the Cascades as well as some lighter upslope snow showers along the north slopes of the Olympics should continue through mid-day .  However, the overall pattern is for drying and cooling as a high amplitude ridge builds offshore and energy from the upper level trough currently over Oregon dives south.

Surface gradients will turn more easterly today. Expect moderately strong and cold east winds through the passes up to crest level Monday through Tuesday including the Mt. Hood area. Monday afternoon through Tuesday night skies will be mostly clear.    

Weather Forecast

Olympics
Monday Morning - Monday Mid-day

Partly cloudy with light to occasionally moderate snow showers along the north slopes of the Olympics. 
Monday Afternoon

Partly sunny with isolated snow showers. 
Monday Night - Tuesday Night

Mostly clear. 
Washington Cascades near and west of the crest including Stevens, Snoqualmie, and White Passes
Monday

Partly sunny with isolated snow showers mainly near the Cascade crest. Moderate to strong east winds developing. 
Monday Night - Tuesday Night

Mostly clear. Moderate to strong east winds beginning to ease Tuesday afternoon through Tuesday night. 
East slopes of the Washington Cascades
Monday

Mostly cloudy with light to occasionally moderate snow showers.  Moderate to strong east winds developing. 
Monday Night - Tuesday Night

Mostly clear. Moderate to strong east winds beginning to ease Tuesday afternoon or Tuesday night. 
Mt. Hood Area
Monday

Mostly cloudy with light to occasionally moderate snow showers.  Moderate to strong east winds developing. 
Monday Night - Tuesday Night

Mostly clear. Moderate to strong east winds beginning to ease late Tuesday afternoon through Tuesday night. 

Issued: 8:21 AM PST Monday, December 29, 2014

Precipitation Forecast

Sunday Sunday
Hurricane Ridge LT 0.10 LT 0.10
Mt Baker Ski Area LT 0.10 LT 0.10
Washington Pass LT 0.10 LT 0.10
Stevens Pass LT 0.10 LT 0.10
Snoqualmie Pass LT 0.10 LT 0.10
Mission Ridge LT 0.25 LT 0.10
Crystal Mt LT 0.10 LT 0.10
Paradise LT 0.10 LT 0.10
White Pass LT 0.10 LT 0.10
Mt Hood Meadows LT 0.25 LT 0.10
Timberline LT 0.25 LT 0.10

LT = less than; WE or Water equivalent is the liquid water equivalent of melted snow in hundredths of inches. As a rough approximation 1 inch of snow = about .10 inches WE, or 10 inches of snow = about 1 inch WE.

Issued: 8:21 AM PST Monday, December 29, 2014

Free Winds at 5000' (mph)

Hurricane Ridge Mt. Baker Stevens to Snoqualmie Pass Mt. Rainier Mt. Hood
Monday Morning NE 15 - 25 NE 10 - 20 E 5 - 15 --- - NW 5 - 15
Monday Mid-day - Tuesday Morning NE 15 - 25 NE 15 - 25 E 15 - 30 --- - E 25 - 35
Tuesday Afternoon N 5 - 15 NW 0 - 10 NE 5 - 15 --- - E 15 - 25
Tuesday Night N 0 - 10 N 0 - 10 NW 0 - 10 --- - E 5 - 15
Hurricane Ridge Elevation
Monday Morning NE 15 - 25
Monday Mid-day - Tuesday Morning NE 15 - 25
Tuesday Afternoon N 5 - 15
Tuesday Night N 0 - 10
Mt. Baker Elevation
Monday Morning NE 10 - 20
Monday Mid-day - Tuesday Morning NE 15 - 25
Tuesday Afternoon NW 0 - 10
Tuesday Night N 0 - 10
Stevens and Snoqualmie Pass Elevation
Monday Morning E 5 - 15
Monday Mid-day - Tuesday Morning E 15 - 30
Tuesday Afternoon NE 5 - 15
Tuesday Night NW 0 - 10
Mt. Rainier Elevation
Monday Morning --- -
Monday Mid-day - Tuesday Morning --- -
Tuesday Afternoon --- -
Tuesday Night --- -
Mt. Hood Elevation
Monday Morning NW 5 - 15
Monday Mid-day - Tuesday Morning E 25 - 35
Tuesday Afternoon E 15 - 25
Tuesday Night E 5 - 15
Hurricane Ridge Direction - Speed
Monday Morning NE 15 - 25
Monday Mid-day - Tuesday Morning NE 15 - 25
Tuesday Afternoon N 5 - 15
Tuesday Night N 0 - 10
Mt. Baker Direction - Speed
Monday Morning NE 10 - 20
Monday Mid-day - Tuesday Morning NE 15 - 25
Tuesday Afternoon NW 0 - 10
Tuesday Night N 0 - 10
Stevens and Snoqualmie Pass Direction - Speed
Monday Morning E 5 - 15
Monday Mid-day - Tuesday Morning E 15 - 30
Tuesday Afternoon NE 5 - 15
Tuesday Night NW 0 - 10
Mt. Rainier Direction - Speed
Monday Morning --- -
Monday Mid-day - Tuesday Morning --- -
Tuesday Afternoon --- -
Tuesday Night --- -
Mt. Hood Direction - Speed
Monday Morning NW 5 - 15
Monday Mid-day - Tuesday Morning E 25 - 35
Tuesday Afternoon E 15 - 25
Tuesday Night E 5 - 15

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
Monday Morning ENE 10 - 20 NE 10 - 20 E 10 - 20 --- - NW 10 - 20
Monday Afternoon NE 15 - 25 NE 15 - 25 NE 15 - 25 --- - NE 15 - 25
Monday Night - Tuesday Mid-day NE 25 - 40 NNE 20 - 30 NE 30 - 40 --- - NE 25 - 40
Tuesday Afternoon N 15 - 25 N 25 - 35 NNE 25 - 35 --- - NE 30 - 45
Tuesday Night N 10 - 20 NNW 15 - 25 NNW 15 - 25 --- - N 15 - 25
Mt. Baker Direction - Speed
Monday Morning ENE 10 - 20
Monday Afternoon NE 15 - 25
Monday Night - Tuesday Mid-day NE 25 - 40
Tuesday Afternoon N 15 - 25
Tuesday Night N 10 - 20
Washington Pass Direction - Speed
Monday Morning NE 10 - 20
Monday Afternoon NE 15 - 25
Monday Night - Tuesday Mid-day NNE 20 - 30
Tuesday Afternoon N 25 - 35
Tuesday Night NNW 15 - 25
Stevens and Snoqualmie Pass Direction - Speed
Monday Morning E 10 - 20
Monday Afternoon NE 15 - 25
Monday Night - Tuesday Mid-day NE 30 - 40
Tuesday Afternoon NNE 25 - 35
Tuesday Night NNW 15 - 25
Mt. Rainier Direction - Speed
Monday Morning --- -
Monday Afternoon --- -
Monday Night - Tuesday Mid-day --- -
Tuesday Afternoon --- -
Tuesday Night --- -
Mt. Hood Direction - Speed
Monday Morning NW 10 - 20
Monday Afternoon NE 15 - 25
Monday Night - Tuesday Mid-day NE 25 - 40
Tuesday Afternoon NE 30 - 45
Tuesday Night N 15 - 25

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.

Issued: 8:21 AM PST Monday, December 29, 2014

Extended Weather Synopsis for Sunday night through Sunday

The upper level ridge offshore will shunt weather systems well to our north into Alaska and the Yukon and the PNW is in for a dry spell to ring in the New Year. Warm air aloft should continue to work inland over the extended period. As the offshore flow and the easterly winds ease Wednesday... a modest jump in freezing levels should be seen over the Cascades and Mt. Hood during the middle of the week. 

A weather system should begin to flatten the upper level ridge Friday... sending some high clouds over the ridge and into the Olympics and North Cascades. 

 

Extended Weather

Olympics, Washington Cascades and Mt. Hood area
Wednesday - Thursday

Mostly clear.  Warming trend.  

Friday

Mostly cloudy Olympics and north Cascades.  Partly cloudy central/south Cascades and Mt. Hood. 

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Previous forecast from Dec 25, 2014

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.