Issued: 2:17 PM PST Monday, December 30, 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 Monday & Wednesday

The upper level ridge stationed in the eastern Pacific most of this month and currently centered along the western US coast will temporarily flatten as a weak frontal system approaches from the northwest.  The Pacific Northwest is in the warm sector and mountain temperatures continue to be quite mild through Monday afternoon.  Light dribs and drabs of rain and snow are affecting most areas today, precipitation coming over the ridge extended further south than expected. 

The frontal boundary will sag south overnight, spreading more widespread precipitation to the central and southern Washington Cascades through Tuesday morning while Mt. Hood will likely see little to no precipitation as the front wanes over Washington. 

A drying trend should ensue Tuesday night with partial clearing beginning Tuesday evening.  Despite some cooling tonight, snow levels will remain on the relatively mild side through the short term. 

Weather Forecast

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

Cloudy with periods of light rain and snow. 

Tuesday Afternoon

Cloudy with light rain and snow ending in the afternoon. 

East slopes of the Washington Cascades
Monday - Tuesday Morning

Cloudy with periods of light rain and snow.  

Tuesday Afternoon

Becoming partly cloudy. 

Mt. Hood Area
Monday - Monday Night

Cloudy.  

Tuesday

Periods of light rain and snow, ending in the afternoon.   

Snow/Freezing Level (ft)

Hurricane Ridge Mt. Baker Washington Pass Leavenworth Stevens Pass Snoqualmie Pass Mt. Rainier, Crystal & White Pass Mt. Hood
Monday Afternoon Snow Level 6000' ' ' ' ' 6000' ' 7000'
Monday Evening Snow Level 5500' ' ' ' ' 4500' ' 6000'
Monday Night - Tuesday Afternoon Snow Level 5000' ' ' ' ' 3500' ' 5000'
Hurricane Ridge Elevation
Monday Afternoon Snow Level
6000'
Monday Evening Snow Level
5500'
Monday Night - Tuesday Afternoon Snow Level
5000'
Tuesday Night Freezing Level
6000'
Mt. Baker Elevation
Monday Afternoon Snow Level
'
Monday Evening Snow Level
'
Monday Night - Tuesday Afternoon Snow Level
'
Tuesday Night Freezing Level
'
Washington Pass Elevation
Monday Afternoon Snow Level
'
Monday Evening Snow Level
'
Monday Night - Tuesday Afternoon Snow Level
'
Tuesday Night Freezing Level
'
Leavenworth Elevation
Monday Afternoon Snow Level
'
Monday Evening Snow Level
'
Monday Night - Tuesday Afternoon Snow Level
'
Tuesday Night Freezing Level
'
Stevens Pass Elevation
Monday Afternoon Snow Level
'
Monday Evening Snow Level
'
Monday Night - Tuesday Afternoon Snow Level
'
Tuesday Night Freezing Level
'
Snoqualmie Pass Elevation
Monday Afternoon Snow Level
6000'
Monday Evening Snow Level
4500'
Monday Night - Tuesday Afternoon Snow Level
3500'
Tuesday Night Freezing Level
4000'
Mt. Rainier & Crystal Elevation
Monday Afternoon Snow Level
'
Monday Evening Snow Level
'
Monday Night - Tuesday Afternoon Snow Level
'
Tuesday Night Freezing Level
'
Mt. Hood Elevation
Monday Afternoon Snow Level
7000'
Monday Evening Snow Level
6000'
Monday Night - Tuesday Afternoon Snow Level
5000'
Tuesday Night Freezing Level
7000'

* 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

Wednesday Wednesday
Hurricane Ridge LT 0.25 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 0.25 - 0.50
Snoqualmie Pass LT 0.10 0.25 - 0.50
Mission Ridge LT 0.10 LT 0.10
Crystal Mt LT 0.10 LT 0.25
Paradise LT 0.10 0.25 - 0.50
White Pass LT 0.10 LT 0.25
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
Monday Afternoon SW 10 - 20 --- - WSW 5 - 15 --- - W 5 - 15
Monday Night - Tuesday Morning W 10 - 20 --- - W 10 - 20 --- - WSW 10 - 20
Hurricane Ridge Elevation
Monday Afternoon SW 10 - 20
Monday Night - Tuesday Morning W 10 - 20
Tuesday Afternoon - Tuesday Night WNW 0 - 10
Mt. Baker Elevation
Monday Afternoon --- -
Monday Night - Tuesday Morning --- -
Tuesday Afternoon - Tuesday Night --- -
Stevens and Snoqualmie Pass Elevation
Monday Afternoon WSW 5 - 15
Monday Night - Tuesday Morning W 10 - 20
Tuesday Afternoon - Tuesday Night WNW 0 - 10
Mt. Rainier Elevation
Monday Afternoon --- -
Monday Night - Tuesday Morning --- -
Tuesday Afternoon - Tuesday Night --- -
Mt. Hood Elevation
Monday Afternoon W 5 - 15
Monday Night - Tuesday Morning WSW 10 - 20
Tuesday Afternoon - Tuesday Night WNW 0 - 10
Hurricane Ridge Direction - Speed
Monday Afternoon SW 10 - 20
Monday Night - Tuesday Morning W 10 - 20
Tuesday Afternoon - Tuesday Night WNW 0 - 10
Mt. Baker Direction - Speed
Monday Afternoon --- -
Monday Night - Tuesday Morning --- -
Tuesday Afternoon - Tuesday Night --- -
Stevens and Snoqualmie Pass Direction - Speed
Monday Afternoon WSW 5 - 15
Monday Night - Tuesday Morning W 10 - 20
Tuesday Afternoon - Tuesday Night WNW 0 - 10
Mt. Rainier Direction - Speed
Monday Afternoon --- -
Monday Night - Tuesday Morning --- -
Tuesday Afternoon - Tuesday Night --- -
Mt. Hood Direction - Speed
Monday Afternoon W 5 - 15
Monday Night - Tuesday Morning WSW 10 - 20
Tuesday Afternoon - Tuesday Night WNW 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 --- - --- - W 30 - 40 --- - W 25 - 35
Monday Night --- - --- - W 35 - 50 --- - WNW 30 - 40
Tuesday --- - --- - NW 25 - 35 --- - NW 30 - 40
Mt. Baker Direction - Speed
Monday Afternoon --- -
Monday Night --- -
Tuesday --- -
Tuesday Night --- -
Washington Pass Direction - Speed
Monday Afternoon --- -
Monday Night --- -
Tuesday --- -
Tuesday Night --- -
Stevens and Snoqualmie Pass Direction - Speed
Monday Afternoon W 30 - 40
Monday Night W 35 - 50
Tuesday NW 25 - 35
Tuesday Night NW 20 - 30
Mt. Rainier Direction - Speed
Monday Afternoon --- -
Monday Night --- -
Tuesday --- -
Tuesday Night --- -
Mt. Hood Direction - Speed
Monday Afternoon W 25 - 35
Monday Night WNW 30 - 40
Tuesday NW 30 - 40
Tuesday Night NW 15 - 25

Extended Weather Synopsis for Wednesday night through Wednesday

Wednesday should be dry but with a fair amount of mid and high clouds for the Olympics and north Cascades with partly cloudy conditions further south. The upper level ridge that rebuilt offshore Tuesday night should shift inland on Wednesday as a weak frontal system pushes into central British Columbia.  A stronger shortwave rounding the base of the trough in northeast Pacific should energize this frontal system, and drive the system into the PNW Thursday afternoon through Thursday night.  This looks to be a stronger system than we have seen in awhile, with moderate to even heavy precipitation for the west slopes and a sharp cooling trend Thursday night. However, this system should pass through rather quickly, and cool and drier conditions should prevail by Friday afternoon. 

Extended Weather

Olympics, Washington Cascades and Mt. Hood Area
Wednesday - Wednesday Night

Mostly cloudy Olympics and north Cascades.  Partly cloudy central and south.   

Thursday Morning

Light rain and snow developing Olympics and north Cascades.  

Thursday Afternoon - Thursday Evening

Light rain and snow spreading south and east.  Precipitation becoming moderate to occasionally heavy west slopes Thursday evening.  

Thursday Night - Friday Morning

Light to moderate rain and snow showers, heaviest west slopes.  Sharp cooling trend.  

Friday Afternoon

Mostly cloudy. Scattered showers for the west slopes.  

Extended Snow/Freezing Levels

Mt. Baker Snoqualmie Pass Mt. Hood Easterly Flow *
Wednesday - Wednesday Night Freezing Level ' - ' 6000' - 7000' 8000' - 9000'
Thursday Snow Level ' - ' 5000' - 6000' 6500' - 7500' *
Thursday Night Snow Level ' - ' 2500' - 3500' 4500' - 5500'
Mt. Baker Elevation
Wednesday - Wednesday Night Freezing Level
' - '
Thursday Snow Level
' - '
(Easterly Flow *)
Thursday Night Snow Level
' - '
Friday Snow Level
' - '
Snoqualmie Pass Elevation
Wednesday - Wednesday Night Freezing Level
6000' - 7000'
Thursday Snow Level
5000' - 6000'
(Easterly Flow *)
Thursday Night Snow Level
2500' - 3500'
Friday Snow Level
1500' - 2500'
Mt. Hood Elevation
Wednesday - Wednesday Night Freezing Level
8000' - 9000'
Thursday Snow Level
6500' - 7500'
(Easterly Flow *)
Thursday Night Snow Level
4500' - 5500'
Friday Snow Level
2000' - 3000'

* 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 30, 2013

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.