Issued: 8:04 AM PDT Tuesday, March 31, 2015
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 & Thursday

A front passed through the Cascades early Tuesday morning.  Behind the front, snow levels have dropped rapidly and a broad area of low level convergence has setup over Snohomish and northern King counties. Westerly flow will continue the convergence zone at low snow levels today... with significant accumulations possible near Stevens Pass and Snoqualmie Passes. Orographic showers and an unstable air mass will keep light to occasionally moderate showers going for the rest of the west slopes, Olympics, and Mt. Hood. Light showers and more sun-breaks are expected for the east slopes. 

A longwave trough positioned over the PNW for the next two days, with cold air aloft creating a classic unstable spring setup. There will be a chance of thunderstorms in the afternoon and evening Tuesday and Wednesday. A shortwave trough swinging through Wednesday afternoon may enhance shower intensity and coverage in the afternoon and evening.  

Weather Forecast

Olympics, Washington Cascades near and west of the crest including Stevens, Snoqualmie, and White Passes and Mt. Hood area
Tuesday - Tuesday Evening

Mostly cloudy with light to occasionally moderate rain and snow showers. Showers heaviest in a Puget Sound convergence zone near Stevens and Snoqualmie Passes. Cooler and breezy. Sunbreaks in the afternoon. Chance of thunderstorms afternoon and evening.  

Tuesday Night - Wednesday Morning

Mostly cloudy with scattered light rain and snow showers. 

Wednesday Afternoon - Wednesday Evening

Mostly cloudy with light to occasionally moderate rain and snow showers. Chance of thunderstorms afternoon and evening.  

East slopes of the Washington Cascades
Tuesday - Tuesday Evening

Partly to mostly cloudy with scattered light rain and snow showers. Showers heaviest east slopes downwind of a Puget Sound convergence zone near Stevens and Snoqualmie Passes. Cooler and breezy. Chance of thunderstorms afternoon and evening near the Cascade crest.  

Tuesday Night - Wednesday Morning

Partly cloudy with isolated light rain and snow showers. 

Wednesday Afternoon - Wednesday Evening

Partly to mostly cloudy with scattered light rain and snow showers. Chance of thunderstorms afternoon and evening near the Cascade crest.  

Snow/Freezing Level (ft)

Hurricane Ridge Mt. Baker Washington Pass Leavenworth Stevens Pass Snoqualmie Pass Mt. Rainier, Crystal & White Pass Mt. Hood
Tuesday Snow Level 3500' 3500' 3500' ' ' 3500' ' 3500'
Tuesday Night - Wednesday Morning Snow Level 2500' 2000' 2500' ' ' 2500' ' 2500'
Wednesday Afternoon Snow Level 3500' 3500' 3500' ' ' 3500' ' 3500'
Hurricane Ridge Elevation
Tuesday Snow Level
3500'
Tuesday Night - Wednesday Morning Snow Level
2500'
Wednesday Afternoon Snow Level
3500'
Wednesday Night Snow Level
2500'
Mt. Baker Elevation
Tuesday Snow Level
3500'
Tuesday Night - Wednesday Morning Snow Level
2000'
Wednesday Afternoon Snow Level
3500'
Wednesday Night Snow Level
2000'
Washington Pass Elevation
Tuesday Snow Level
3500'
Tuesday Night - Wednesday Morning Snow Level
2500'
Wednesday Afternoon Snow Level
3500'
Wednesday Night Snow Level
2500'
Leavenworth Elevation
Tuesday Snow Level
'
Tuesday Night - Wednesday Morning Snow Level
'
Wednesday Afternoon Snow Level
'
Wednesday Night Snow Level
'
Stevens Pass Elevation
Tuesday Snow Level
'
Tuesday Night - Wednesday Morning Snow Level
'
Wednesday Afternoon Snow Level
'
Wednesday Night Snow Level
'
Snoqualmie Pass Elevation
Tuesday Snow Level
3500'
Tuesday Night - Wednesday Morning Snow Level
2500'
Wednesday Afternoon Snow Level
3500'
Wednesday Night Snow Level
2500'
Mt. Rainier & Crystal Elevation
Tuesday Snow Level
'
Tuesday Night - Wednesday Morning Snow Level
'
Wednesday Afternoon Snow Level
'
Wednesday Night Snow Level
'
Mt. Hood Elevation
Tuesday Snow Level
3500'
Tuesday Night - Wednesday Morning Snow Level
2500'
Wednesday Afternoon Snow Level
3500'
Wednesday Night Snow Level
2500'

* 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 0.25 LT 0.25
Mt Baker Ski Area 0.25 - 0.50 LT 0.25
Washington Pass LT 0.25 LT 0.10
Stevens Pass 0 - 1.00 LT 0.25
Snoqualmie Pass 0.50 - 1.00 0.25 - 0.50
Mission Ridge LT 0.10 LT 0.10
Crystal Mt LT 0.25 LT 0.25
Paradise 0.50 - 0.75 0.25 - 0.50
White Pass 0 - 0.50 LT 0.25
Mt Hood Meadows 0 - 0.50 0.25 - 0.50
0 - 0.75 0 - 0.50

Free Winds at 5000' (mph)

Hurricane Ridge Mt. Baker Stevens to Snoqualmie Pass Mt. Rainier Mt. Hood
Tuesday Morning W 15 - 25 WSW 15 - 25 SW 15 - 25 --- - WNW 15 - 25
Tuesday Afternoon W 10 - 20 WSW 10 - 20 WSW 15 - 25 --- - W 20 - 30
Tuesday Night - Wednesday Morning W 10 - 20 SW 10 - 20 W 10 - 20 --- - W 15 - 25
Hurricane Ridge Elevation
Tuesday Morning W 15 - 25
Tuesday Afternoon W 10 - 20
Tuesday Night - Wednesday Morning W 10 - 20
Wednesday Afternoon - Wednesday Night NW 5 - 15
Mt. Baker Elevation
Tuesday Morning WSW 15 - 25
Tuesday Afternoon WSW 10 - 20
Tuesday Night - Wednesday Morning SW 10 - 20
Wednesday Afternoon - Wednesday Night W 0 - 10
Stevens and Snoqualmie Pass Elevation
Tuesday Morning SW 15 - 25
Tuesday Afternoon WSW 15 - 25
Tuesday Night - Wednesday Morning W 10 - 20
Wednesday Afternoon - Wednesday Night WNW 5 - 15
Mt. Rainier Elevation
Tuesday Morning --- -
Tuesday Afternoon --- -
Tuesday Night - Wednesday Morning --- -
Wednesday Afternoon - Wednesday Night --- -
Mt. Hood Elevation
Tuesday Morning WNW 15 - 25
Tuesday Afternoon W 20 - 30
Tuesday Night - Wednesday Morning W 15 - 25
Wednesday Afternoon - Wednesday Night WNW 15 - 25
Hurricane Ridge Direction - Speed
Tuesday Morning W 15 - 25
Tuesday Afternoon W 10 - 20
Tuesday Night - Wednesday Morning W 10 - 20
Wednesday Afternoon - Wednesday Night NW 5 - 15
Mt. Baker Direction - Speed
Tuesday Morning WSW 15 - 25
Tuesday Afternoon WSW 10 - 20
Tuesday Night - Wednesday Morning SW 10 - 20
Wednesday Afternoon - Wednesday Night W 0 - 10
Stevens and Snoqualmie Pass Direction - Speed
Tuesday Morning SW 15 - 25
Tuesday Afternoon WSW 15 - 25
Tuesday Night - Wednesday Morning W 10 - 20
Wednesday Afternoon - Wednesday Night WNW 5 - 15
Mt. Rainier Direction - Speed
Tuesday Morning --- -
Tuesday Afternoon --- -
Tuesday Night - Wednesday Morning --- -
Wednesday Afternoon - Wednesday Night --- -
Mt. Hood Direction - Speed
Tuesday Morning WNW 15 - 25
Tuesday Afternoon W 20 - 30
Tuesday Night - Wednesday Morning W 15 - 25
Wednesday Afternoon - Wednesday Night WNW 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.

Free Winds at 9000' (mph)

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

Extended Weather Synopsis for Thursday night through Thursday

Snow levels will remain cool through the entire forecast period; notable because extended cool periods have been sorely lacking this season. Thursday should be a lull day with a transitory shortwave ridge shifting over the area. However, there should be enough low level moisture leftover to keep it mostly cloudy with a chance of showers along the west slopes.  Forecast models now have the next frontal system digging from the northwest arriving a bit earlier... and high and mid clouds should start spreading over the Olypmics and north Cascades Thursday afternoon.

Light rain and snow should develop over the entire area by early Friday morning. Another cool and unstable trough should setup over the area Friday afternoon through Saturday with low snow levels and light to occasionally moderate showers once again.

Extended Weather

Olympics, Washington Cascades near and west of the crest including Stevens, Snoqualmie, and White Passes and Mt. Hood Area
Thursday - Thursday Evening

Partly cloudy becoming mostly cloudy in the afternoon and evening.  Chance of light rain and snow showers. 

Thursday Night - Friday Morning

Light rain and snow developing Olympics and north Cascades and spreading south Friday morning. 

Friday Afternoon - Saturday

Mostly cloudy with light to occasionally moderate rain and snow showers Olympics, west slopes of the Cascades and Mt. Hood area. Partly to mostly cloudy with scattered light rain and snow showers east slopes of the Cascades. 

Extended Snow/Freezing Levels

Mt. Baker Snoqualmie Pass Mt. Hood Easterly Flow *
Mt. Baker Elevation
Thursday - Saturday Snow Level
2500' - 3500'
Snoqualmie Pass Elevation
Thursday - Saturday Snow Level
2500' - 3500'
Mt. Hood Elevation
Thursday - Saturday Snow Level
3000' - 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 Mar 30, 2015

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