Issued: 3:15 PM PST Tuesday, December 26, 2017
by Robert Hahn

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 & Thursday

A continental-scale, broad trough continues to bring cold area to the majority of North America and the Pacific Northwest will be experiencing this cold airmass in place on Tuesday morning with a slight temperature gradient across the Cascades producing light to moderate easterly pass-level winds on Tuesday. A weak shortwave ridge extends from our coastal waters up to Alaska and will help bring fair weather to the region on Tuesday. However, a weak upper level moisture band will bring some cloudier skies and a brief chance of light precipitation to our region on Tuesday afternoon. A rotating upper-level and surface low in the North Pacific will begin to move eastward, flattening the shortwave ridge Tuesday afternoon into Tuesday night. Light onshore winds will develop Tuesday afternoon and with the ridge breaking down, high clouds will make their way into our region.

On Wednesday, occasional light precipitation may make its way into our region during the day, with little organization expected.

Wednesday night, a more significant warm front associated with the primary eastward-moving low will begin spreading moisture into the Washington coast by morning.

Weather Forecast

Olympics
Tuesday Increasing clouds. A chance of a light snow shower.
Tuesday Night Mostly cloudy and gradually warming
Wednesday Mostly cloudy with a chance of a few rain or snow showers. Gradual warming.
Wednesday Night Clouds thickening with winds shifting to the south and more consistent light rain or snow arriving by morning.
Washington Cascades near and west of the Crest including Stevens, Snoqualmie and White Passes
Tuesday Increasing high clouds with a chance of a light snow shower, particularly south.
Tuesday Night Mostly cloudy.
Wednesday Mostly cloudy with gradual warming and a slight chance of snow showers.
Wednesday Night Clouds thickening with winds shifting to the south and continued chances of rain or snow showers.
East Slopes of the Washington Cascades
Tuesday Increasing clouds with a chance of a light snow shower, especially south.
Tuesday Night Mostly cloudy.
Wednesday Mostly cloudy with a slight chance of snow showers at higher elevations.
Wednesday Night Clouds thickening with winds shifting to the south and continued chances of rain or snow showers at higher elevations.
Mt. Hood
Tuesday Increasing mid-level clouds with fog and low cloud below the inversion in the eastern part of the are. A chance of a light snow shower.
Tuesday Night Mostly cloudy with a slight chance of rain or snow showers. Warming trend.
Wednesday Cloudy with a chance of rain or snow showers. Warming continuing in the morning.
Wednesday Night Clouds thickening with winds shifting to the south and continued chances of rain or snow showers.

Issued: 3:15 PM PST Tuesday, December 26, 2017

Snow/Freezing Level (ft)

Hurricane Ridge Mt. Baker Washington Pass Leavenworth Stevens Pass Snoqualmie Pass Mt. Rainier, Crystal & White Pass Mt. Hood
Tuesday Afternoon Freezing Level * 2000' 1000' 1000' ' ' 1000' ' 2000'
Tuesday Night Snow Level * 2500' 500' 0' ' ' 1000' ' 3500'
Wednesday Morning Snow Level * 2500' 500' 500' ' ' 2000' ' 4000'
Wednesday Afternoon Snow Level * 3000' 1500' 1500' ' ' 2500' ' 4500'
Wednesday Night Snow Level * 3500' 2500' 1500' ' ' 2500' ' 4500'
Hurricane Ridge Elevation
Tuesday Afternoon Freezing Level
2000'
(Easterly Flow *)
Tuesday Night Snow Level
2500'
(Easterly Flow *)
Wednesday Morning Snow Level
2500'
(Easterly Flow *)
Wednesday Afternoon Snow Level
3000'
(Easterly Flow *)
Wednesday Night Snow Level
3500'
(Easterly Flow *)
Mt. Baker Elevation
Tuesday Afternoon Freezing Level
1000'
(Easterly Flow *)
Tuesday Night Snow Level
500'
(Easterly Flow *)
Wednesday Morning Snow Level
500'
(Easterly Flow *)
Wednesday Afternoon Snow Level
1500'
(Easterly Flow *)
Wednesday Night Snow Level
2500'
(Easterly Flow *)
Washington Pass Elevation
Tuesday Afternoon Freezing Level
1000'
(Easterly Flow *)
Tuesday Night Snow Level
0'
(Easterly Flow *)
Wednesday Morning Snow Level
500'
(Easterly Flow *)
Wednesday Afternoon Snow Level
1500'
(Easterly Flow *)
Wednesday Night Snow Level
1500'
(Easterly Flow *)
Leavenworth Elevation
Tuesday Afternoon Freezing Level
'
(Easterly Flow *)
Tuesday Night Snow Level
'
(Easterly Flow *)
Wednesday Morning Snow Level
'
(Easterly Flow *)
Wednesday Afternoon Snow Level
'
(Easterly Flow *)
Wednesday Night Snow Level
'
(Easterly Flow *)
Stevens Pass Elevation
Tuesday Afternoon Freezing Level
'
(Easterly Flow *)
Tuesday Night Snow Level
'
(Easterly Flow *)
Wednesday Morning Snow Level
'
(Easterly Flow *)
Wednesday Afternoon Snow Level
'
(Easterly Flow *)
Wednesday Night Snow Level
'
(Easterly Flow *)
Snoqualmie Pass Elevation
Tuesday Afternoon Freezing Level
1000'
(Easterly Flow *)
Tuesday Night Snow Level
1000'
(Easterly Flow *)
Wednesday Morning Snow Level
2000'
(Easterly Flow *)
Wednesday Afternoon Snow Level
2500'
(Easterly Flow *)
Wednesday Night Snow Level
2500'
(Easterly Flow *)
Mt. Rainier & Crystal Elevation
Tuesday Afternoon Freezing Level
'
(Easterly Flow *)
Tuesday Night Snow Level
'
(Easterly Flow *)
Wednesday Morning Snow Level
'
(Easterly Flow *)
Wednesday Afternoon Snow Level
'
(Easterly Flow *)
Wednesday Night Snow Level
'
(Easterly Flow *)
Mt. Hood Elevation
Tuesday Afternoon Freezing Level
2000'
(Easterly Flow *)
Tuesday Night Snow Level
3500'
(Easterly Flow *)
Wednesday Morning Snow Level
4000'
(Easterly Flow *)
Wednesday Afternoon Snow Level
4500'
(Easterly Flow *)
Wednesday Night Snow Level
4500'
(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.

Precipitation Forecast

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

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: 3:15 PM PST Tuesday, December 26, 2017

Free Winds at 5000' (mph)

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

Free Winds at 9000' (mph)

Mt. Baker Washington Pass Stevens to Snoqualmie Pass Mt. Rainier Mt. Hood
Tuesday Afternoon WSW 20 - 30 WSW 20 - 30 W 30 - 40 --- - WSW 35 - 50
Tuesday Night W 20 - 30 W 20 - 30 W 35 - 50 --- - W 40 - 60
Wednesday Morning W 25 - 35 W 25 - 35 W 35 - 50 --- - W 35 - 50
Wednesday Afternoon W 25 - 35 W 20 - 30 W 35 - 50 --- - W 25 - 35
Wednesday Night WSW 20 - 30 WSW 20 - 30 WSW 30 - 40 --- - WSW 25 - 35
Mt. Baker Direction - Speed
Tuesday Afternoon WSW 20 - 30
Tuesday Night W 20 - 30
Wednesday Morning W 25 - 35
Wednesday Afternoon W 25 - 35
Wednesday Night WSW 20 - 30
Washington Pass Direction - Speed
Tuesday Afternoon WSW 20 - 30
Tuesday Night W 20 - 30
Wednesday Morning W 25 - 35
Wednesday Afternoon W 20 - 30
Wednesday Night WSW 20 - 30
Stevens and Snoqualmie Pass Direction - Speed
Tuesday Afternoon W 30 - 40
Tuesday Night W 35 - 50
Wednesday Morning W 35 - 50
Wednesday Afternoon W 35 - 50
Wednesday Night WSW 30 - 40
Mt. Rainier Direction - Speed
Tuesday Afternoon --- -
Tuesday Night --- -
Wednesday Morning --- -
Wednesday Afternoon --- -
Wednesday Night --- -
Mt. Hood Direction - Speed
Tuesday Afternoon WSW 35 - 50
Tuesday Night W 40 - 60
Wednesday Morning W 35 - 50
Wednesday Afternoon W 25 - 35
Wednesday Night WSW 25 - 35

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: 3:15 PM PST Tuesday, December 26, 2017

Extended Weather Synopsis for Thursday night through Thursday

A moisture-laden system arrives Thursday with a warm front bringing rain and snow to the Olympics and North Cascades on Thursday morning, followed by cold-frontal precipitation that spreads south with increasing intensity during the afternoon hours. With a very cold air mass in place east of the Cascade crest, anticipated easterly flow in the passes should keep snow in the passes until the wind shift to westerly in the late afternoon when there might be a switch to rain, mainly at Snoqualmie. Strong S-SW crest-level winds are anticipated Friday afternoon.

The cold-frontal passage during the late afternoon on Thursday should give Washington some reprieve from the intense precipitation Thursday night. The cold front will stall over central Oregon Thursday night, continuing the heavier rain and snow south of Hood.

On Friday, a strong very well-organized surface low will track toward NW Washington and is anticipated to make landfall Friday afternoon. It should bring rapidly increasing precipitation rates during the morning hours in most areas as the warm-frontal precipitation lifts northward over the Cascades. Very strong and shifting crest level winds are anticipated with Friday's system as well as strong post-frontal westerly flow to follow it Friday night into Saturday morning, cutting off Saturday afternoon..

 

Extended Weather

Olympics, Washington Cascades and Mt. Hood Area
Thursday Increasing moderate to heavy rain and snow during the day Thursday spreading southward during the day. Precipitation becomes moderate and showery Thursday night. This storm may produce a changeover to rain at Snoqualmie pass late in the day. Friday Increasing moderate to very heavy precipitation will lift northward over all areas Friday. The storm may produced mixed precipitation types (snow, freezing rain, or rain), especially at Snoqualmie. Moderate to heavy post-frontal showers should continue Friday night with decreasing and shifting winds. Saturday Continued post-frontal showers will become light to moderate Saturday morning, before ending Saturday afternoon as westerly winds decrease and temperatures continue to cool.

Extended Snow/Freezing Levels

Mt. Baker Snoqualmie Pass Mt. Hood Easterly Flow *
Thursday Snow Level 3000' - 5000' 3000' - 5000' 5000' - 7000' *
Thursday Night Snow Level 3000' - 4500' 3500' - 5500' 5000' - 7000'
Friday Snow Level 3000' - 5000' 3500' - 5500' 6000' - 8000' *
Friday Night Snow Level 3000' - 5000' 3500' - 5500' 4500' - 6500'
Saturday Snow Level 1500' - 3500' 2000' - 4000' 3000' - 5000'
Mt. Baker Elevation
Thursday Snow Level
3000' - 5000'
(Easterly Flow *)
Thursday Night Snow Level
3000' - 4500'
Friday Snow Level
3000' - 5000'
(Easterly Flow *)
Friday Night Snow Level
3000' - 5000'
Saturday Snow Level
1500' - 3500'
Snoqualmie Pass Elevation
Thursday Snow Level
3000' - 5000'
(Easterly Flow *)
Thursday Night Snow Level
3500' - 5500'
Friday Snow Level
3500' - 5500'
(Easterly Flow *)
Friday Night Snow Level
3500' - 5500'
Saturday Snow Level
2000' - 4000'
Mt. Hood Elevation
Thursday Snow Level
5000' - 7000'
(Easterly Flow *)
Thursday Night Snow Level
5000' - 7000'
Friday Snow Level
6000' - 8000'
(Easterly Flow *)
Friday Night Snow Level
4500' - 6500'
Saturday Snow Level
3000' - 5000'

* 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 26, 2017

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