Issued: 3:28 PM PST Monday, December 11, 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 Monday & Monday

On Monday, a large ridge remains centered over the intermountain west, bringing unseasonably warm temperatures to the higher elevations with a strong inversion near the surface. A compact low embedded in SW flow will work its way into our coastal waters during the day. On Monday night, the low pressure reaches the central BC coastline. The weakening associated front should help to flatten the ridge and reduce the inversion as temperatures aloft decrease and more mixing of the atmosphere occurs. The system will bring some clouds to the region, but very little or no precipitation. Tuesday, the ridge axis shifts offshore and re-establishes Tuesday night.

Weather Forecast

Olympics
Monday

Mostly sunny and mild.
Monday Night

Clear early, becoming mostly cloudy by morning.
Tuesday

Mostly cloudy, becoming partly cloudy in the afternoon.
Tuesday Night

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

Mostly sunny with some low clouds near pass level.
Monday Night

Mostly clear with high clouds increasing by morning.
Tuesday

Mostly cloudy.
Tuesday Night

Becoming mostly clear.
East slopes of the Washington Cascades
Monday

Mostly sunny with low clouds, lower to mid-slope.
Monday Night

Mostly clear with high clouds increasing by morning.
Tuesday

Mostly cloudy.
Tuesday Night

Becoming mostly clear.
Mt. Hood Area
Monday

Mostly sunny with some low clouds in the morning on the east side of the region.
Monday Night

Mostly clear with high clouds increasing by morning.
Tuesday

Mostly cloudy.
Tuesday Night

Becoming mostly clear.

Issued: 3:28 PM PST Monday, December 11, 2017

Snow/Freezing Level (ft)

Hurricane Ridge Mt. Baker Washington Pass Leavenworth Stevens Pass Snoqualmie Pass Mt. Rainier, Crystal & White Pass Mt. Hood
Monday Afternoon Freezing Level * 11500' 12000' 12500' ' ' 12500' ' 12500'
Monday Night Freezing Level * 9000' 8000' 9000' ' ' 9500' ' 11500'
Tuesday Morning Freezing Level * 9000' 8000' 9000' ' ' 9500' ' 11500'
Tuesday Afternoon Freezing Level * 8500' 7500' 7500' ' ' 8000' ' 11000'
Tuesday Night Freezing Level * 10500' 8500' 9000' ' ' 10000' ' 11500'
Hurricane Ridge Elevation
Monday Afternoon Freezing Level
11500'
(Easterly Flow *)
Monday Night Freezing Level
9000'
(Easterly Flow *)
Tuesday Morning Freezing Level
9000'
(Easterly Flow *)
Tuesday Afternoon Freezing Level
8500'
(Easterly Flow *)
Tuesday Night Freezing Level
10500'
(Easterly Flow *)
Mt. Baker Elevation
Monday Afternoon Freezing Level
12000'
(Easterly Flow *)
Monday Night Freezing Level
8000'
(Easterly Flow *)
Tuesday Morning Freezing Level
8000'
(Easterly Flow *)
Tuesday Afternoon Freezing Level
7500'
(Easterly Flow *)
Tuesday Night Freezing Level
8500'
(Easterly Flow *)
Washington Pass Elevation
Monday Afternoon Freezing Level
12500'
(Easterly Flow *)
Monday Night Freezing Level
9000'
(Easterly Flow *)
Tuesday Morning Freezing Level
9000'
(Easterly Flow *)
Tuesday Afternoon Freezing Level
7500'
(Easterly Flow *)
Tuesday Night Freezing Level
9000'
(Easterly Flow *)
Leavenworth Elevation
Monday Afternoon Freezing Level
'
(Easterly Flow *)
Monday Night Freezing Level
'
(Easterly Flow *)
Tuesday Morning Freezing Level
'
(Easterly Flow *)
Tuesday Afternoon Freezing Level
'
(Easterly Flow *)
Tuesday Night Freezing Level
'
(Easterly Flow *)
Stevens Pass Elevation
Monday Afternoon Freezing Level
'
(Easterly Flow *)
Monday Night Freezing Level
'
(Easterly Flow *)
Tuesday Morning Freezing Level
'
(Easterly Flow *)
Tuesday Afternoon Freezing Level
'
(Easterly Flow *)
Tuesday Night Freezing Level
'
(Easterly Flow *)
Snoqualmie Pass Elevation
Monday Afternoon Freezing Level
12500'
(Easterly Flow *)
Monday Night Freezing Level
9500'
(Easterly Flow *)
Tuesday Morning Freezing Level
9500'
(Easterly Flow *)
Tuesday Afternoon Freezing Level
8000'
(Easterly Flow *)
Tuesday Night Freezing Level
10000'
(Easterly Flow *)
Mt. Rainier & Crystal Elevation
Monday Afternoon Freezing Level
'
(Easterly Flow *)
Monday Night Freezing Level
'
(Easterly Flow *)
Tuesday Morning Freezing Level
'
(Easterly Flow *)
Tuesday Afternoon Freezing Level
'
(Easterly Flow *)
Tuesday Night Freezing Level
'
(Easterly Flow *)
Mt. Hood Elevation
Monday Afternoon Freezing Level
12500'
(Easterly Flow *)
Monday Night Freezing Level
11500'
(Easterly Flow *)
Tuesday Morning Freezing Level
11500'
(Easterly Flow *)
Tuesday Afternoon Freezing Level
11000'
(Easterly Flow *)
Tuesday Night Freezing Level
11500'
(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

Monday Monday
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 0.10 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 0.10 LT 0.10
Timberline LT 0.10 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: 3:28 PM PST Monday, December 11, 2017

Free Winds at 5000' (mph)

Hurricane Ridge Mt. Baker Stevens to Snoqualmie Pass Mt. Rainier Mt. Hood
Monday Afternoon SSW 5 - 15 S 15 - 25 S 15 - 25 --- - SW 0 - 10
Monday Night SSW 5 - 15 S 10 - 20 W 5 - 15 --- - WSW 5 - 15
Tuesday Morning SSW 0 - 10 S 5 - 15 W 5 - 15 --- - W 0 - 10
Tuesday Afternoon SW 0 - 10 SSW 0 - 10 W 5 - 15 --- - W 5 - 15
Tuesday Night VAR 0 - 10 VAR 0 - 10 VAR 0 - 10 --- - VAR 0 - 10
Hurricane Ridge Elevation
Monday Afternoon SSW 5 - 15
Monday Night SSW 5 - 15
Tuesday Morning SSW 0 - 10
Tuesday Afternoon SW 0 - 10
Tuesday Night VAR 0 - 10
Mt. Baker Elevation
Monday Afternoon S 15 - 25
Monday Night S 10 - 20
Tuesday Morning S 5 - 15
Tuesday Afternoon SSW 0 - 10
Tuesday Night VAR 0 - 10
Stevens and Snoqualmie Pass Elevation
Monday Afternoon S 15 - 25
Monday Night W 5 - 15
Tuesday Morning W 5 - 15
Tuesday Afternoon W 5 - 15
Tuesday Night VAR 0 - 10
Mt. Rainier Elevation
Monday Afternoon --- -
Monday Night --- -
Tuesday Morning --- -
Tuesday Afternoon --- -
Tuesday Night --- -
Mt. Hood Elevation
Monday Afternoon SW 0 - 10
Monday Night WSW 5 - 15
Tuesday Morning W 0 - 10
Tuesday Afternoon W 5 - 15
Tuesday Night VAR 0 - 10
Hurricane Ridge Direction - Speed
Monday Afternoon SSW 5 - 15
Monday Night SSW 5 - 15
Tuesday Morning SSW 0 - 10
Tuesday Afternoon SW 0 - 10
Tuesday Night VAR 0 - 10
Mt. Baker Direction - Speed
Monday Afternoon S 15 - 25
Monday Night S 10 - 20
Tuesday Morning S 5 - 15
Tuesday Afternoon SSW 0 - 10
Tuesday Night VAR 0 - 10
Stevens and Snoqualmie Pass Direction - Speed
Monday Afternoon S 15 - 25
Monday Night W 5 - 15
Tuesday Morning W 5 - 15
Tuesday Afternoon W 5 - 15
Tuesday Night VAR 0 - 10
Mt. Rainier Direction - Speed
Monday Afternoon --- -
Monday Night --- -
Tuesday Morning --- -
Tuesday Afternoon --- -
Tuesday Night --- -
Mt. Hood Direction - Speed
Monday Afternoon SW 0 - 10
Monday Night WSW 5 - 15
Tuesday Morning W 0 - 10
Tuesday Afternoon W 5 - 15
Tuesday Night VAR 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
Monday Afternoon SSW 20 - 30 SSW 20 - 30 SSW 15 - 25 --- - SSW 15 - 25
Monday Night SW 35 - 50 WSW 30 - 40 WSW 25 - 35 --- - WSW 15 - 25
Tuesday Morning SW 35 - 50 WSW 30 - 40 WSW 25 - 35 --- - WSW 15 - 25
Tuesday Afternoon WSW 15 - 25 WSW 10 - 20 W 25 - 35 --- - W 15 - 25
Tuesday Night WNW 5 - 15 WNW 10 - 20 WNW 10 - 20 --- - WNW 10 - 20
Mt. Baker Direction - Speed
Monday Afternoon SSW 20 - 30
Monday Night SW 35 - 50
Tuesday Morning SW 35 - 50
Tuesday Afternoon WSW 15 - 25
Tuesday Night WNW 5 - 15
Washington Pass Direction - Speed
Monday Afternoon SSW 20 - 30
Monday Night WSW 30 - 40
Tuesday Morning WSW 30 - 40
Tuesday Afternoon WSW 10 - 20
Tuesday Night WNW 10 - 20
Stevens and Snoqualmie Pass Direction - Speed
Monday Afternoon SSW 15 - 25
Monday Night WSW 25 - 35
Tuesday Morning WSW 25 - 35
Tuesday Afternoon W 25 - 35
Tuesday Night WNW 10 - 20
Mt. Rainier Direction - Speed
Monday Afternoon --- -
Monday Night --- -
Tuesday Morning --- -
Tuesday Afternoon --- -
Tuesday Night --- -
Mt. Hood Direction - Speed
Monday Afternoon SSW 15 - 25
Monday Night WSW 15 - 25
Tuesday Morning WSW 15 - 25
Tuesday Afternoon W 15 - 25
Tuesday Night WNW 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.

Issued: 3:28 PM PST Monday, December 11, 2017

Extended Weather Synopsis for Monday night through Monday

Wednesday brings our last day of the ridge in its full prominence. By late Wednesday, the first of a series of systems will enter our coastal waters. The system begins to break down the ridge on Thursday as flow becomes more westerly aloft. By late Thursday night, the frontal system will begin impacting our region with increasing flow aloft and precipitation. The frontal system will bring rapid cooling, likely in the late morning although models diverge significantly on timing. The post-frontal flow will bring enhanced orographic showers and a strong westerly wind push.

Extended Weather

Olympics, Washington Cascades, and Mt Hood areas
Wednesday

Mostly sunny, but some thin high clouds may spread into the Olympics and Washington Cascades.

Wednesday Night

Mostly clear with some high clouds; areas of low clouds, passes and lower slopes of the eastern Cascades.

Thursday

High clouds increasing.

Thursday Night

Increasing light to moderate rain and high elevation snow by morning.

Friday

Light to moderate rain and high elevation snow becoming light to moderate showers in the afternoon, heaviest in the central Cascades.

Extended Snow/Freezing Levels

Mt. Baker Snoqualmie Pass Mt. Hood Easterly Flow *
Wednesday Freezing Level 9500' - 11500' 10000' - 11000' 11500' - 12500' *
Wednesday Night Freezing Level 10000' - 11000' 10500' - 11500' 12000' - 13000' *
Thursday Freezing Level 10000' - 11000' 11000' - 12000' 12000' - 13000' *
Thursday Night Snow Level 5500' - 7500' 7000' - 9000' 8500' - 10500' *
Friday Snow Level 2500' - 4000' 2500' - 4000' 2500' - 4000'
Mt. Baker Elevation
Wednesday Freezing Level
9500' - 11500'
(Easterly Flow *)
Wednesday Night Freezing Level
10000' - 11000'
(Easterly Flow *)
Thursday Freezing Level
10000' - 11000'
(Easterly Flow *)
Thursday Night Snow Level
5500' - 7500'
(Easterly Flow *)
Friday Snow Level
2500' - 4000'
Snoqualmie Pass Elevation
Wednesday Freezing Level
10000' - 11000'
(Easterly Flow *)
Wednesday Night Freezing Level
10500' - 11500'
(Easterly Flow *)
Thursday Freezing Level
11000' - 12000'
(Easterly Flow *)
Thursday Night Snow Level
7000' - 9000'
(Easterly Flow *)
Friday Snow Level
2500' - 4000'
Mt. Hood Elevation
Wednesday Freezing Level
11500' - 12500'
(Easterly Flow *)
Wednesday Night Freezing Level
12000' - 13000'
(Easterly Flow *)
Thursday Freezing Level
12000' - 13000'
(Easterly Flow *)
Thursday Night Snow Level
8500' - 10500'
(Easterly Flow *)
Friday Snow Level
2500' - 4000'

* 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 11, 2017

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