Issued: 2:41 PM PDT Thursday, April 26, 2018
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 Thursday & Friday

A strong ridge of high pressure is bringing very warm temperatures for late April across the Pacific Northwest on Thursday. Temperatures at most NWAC stations are in the 50's to low 70's, under clear skies. A cutoff upper low off the California coast will be the next weather player in the Pacific Northwest. A marine stratus cloud deck extends southward along the U.S. coastline from Tatoosh Island, but the stratus clouds are not making their way inland.

The upper low will drift north and east Thursday night. This will shift the high pressure ridge eastward, allowing a marine push to develop during the early morning hours and beginning to bring the stratus deck onshore with SW flow at low levels.

On Friday, the ridge continues shifting east as the marine push will cool locations west of the Cascade crest, from south to north as clouds brush up against the slopes of the Cascades at low levels while upper level clouds also move in from the south. Locations east of the Cascade crest will see minimal cloud cover and very limited, if any, cooling. Very light rain may develop Friday afternoon near Mt. Hood as the upper low continues to drift toward the Pacific Northwest.

On Friday night, a band of rain associated with the upper low will work its way northward across Washington state, into British Columbia.

Weather Forecast

Olympics
Thursday Sunny and very warm.
Thursday Night Warm and clear.
Friday Clouds increasing in the afternoon with slight cooling.
Washington Cascades near and west of the Crest including Stevens, Snoqualmie and White Passes
Thursday Sunny and very warm.
Thursday Night Warm and clear.
Friday Low level clouds increasing and thickening with light westerly flow developing. Cooling during the afternoon, particularly in the south.
East Slopes of the Washington Cascades
Thursday Sunny and very warm.
Thursday Night Warm and clear.
Friday Very warm and mostly sunny, with mid-level clouds arriving from the south, with some slight cooling late in the day.
Mt. Hood
Thursday Sunny and very warm.
Thursday Night Clear early with clouds arriving during the early morning hours with westerly winds developing.
Friday Clouds lowering and thickening with a chance of light rain in the afternoon. Cooling temperatures.

Snow/Freezing Level (ft)

Hurricane Ridge Mt. Baker Washington Pass Leavenworth Stevens Pass Snoqualmie Pass Mt. Rainier, Crystal & White Pass Mt. Hood
Thursday Afternoon Freezing Level * 12500' 12050' 12500' ' ' 12500' ' 12500'
Thursday Night Freezing Level * 12000' 12000' 12000' ' ' 12000' ' 12000'
Friday Morning Freezing Level 11500' 12000' 12000' ' ' 12000' ' 11500'
Friday Afternoon Snow Level 9500' 10500' 10500' ' ' 10000' ' 8000'
Hurricane Ridge Elevation
Thursday Afternoon Freezing Level
12500'
(Easterly Flow *)
Thursday Night Freezing Level
12000'
(Easterly Flow *)
Friday Morning Freezing Level
11500'
Friday Afternoon Snow Level
9500'
Friday Night Snow Level
7000'
Mt. Baker Elevation
Thursday Afternoon Freezing Level
12050'
(Easterly Flow *)
Thursday Night Freezing Level
12000'
(Easterly Flow *)
Friday Morning Freezing Level
12000'
Friday Afternoon Snow Level
10500'
Friday Night Snow Level
7500'
Washington Pass Elevation
Thursday Afternoon Freezing Level
12500'
(Easterly Flow *)
Thursday Night Freezing Level
12000'
(Easterly Flow *)
Friday Morning Freezing Level
12000'
Friday Afternoon Snow Level
10500'
Friday Night Snow Level
10500'
Leavenworth Elevation
Thursday Afternoon Freezing Level
'
(Easterly Flow *)
Thursday Night Freezing Level
'
(Easterly Flow *)
Friday Morning Freezing Level
'
Friday Afternoon Snow Level
'
Friday Night Snow Level
'
Stevens Pass Elevation
Thursday Afternoon Freezing Level
'
(Easterly Flow *)
Thursday Night Freezing Level
'
(Easterly Flow *)
Friday Morning Freezing Level
'
Friday Afternoon Snow Level
'
Friday Night Snow Level
'
Snoqualmie Pass Elevation
Thursday Afternoon Freezing Level
12500'
(Easterly Flow *)
Thursday Night Freezing Level
12000'
(Easterly Flow *)
Friday Morning Freezing Level
12000'
Friday Afternoon Snow Level
10000'
Friday Night Snow Level
7000'
Mt. Rainier & Crystal Elevation
Thursday Afternoon Freezing Level
'
(Easterly Flow *)
Thursday Night Freezing Level
'
(Easterly Flow *)
Friday Morning Freezing Level
'
Friday Afternoon Snow Level
'
Friday Night Snow Level
'
Mt. Hood Elevation
Thursday Afternoon Freezing Level
12500'
(Easterly Flow *)
Thursday Night Freezing Level
12000'
(Easterly Flow *)
Friday Morning Freezing Level
11500'
Friday Afternoon Snow Level
8000'
Friday Night Snow Level
6000'

* 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

Friday Friday
Hurricane Ridge LT 0.10 LT 0.25
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 0.25
Mission Ridge LT 0.10 LT 0.25
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
LT 0.10 LT 0.25

Free Winds at 5000' (mph)

Hurricane Ridge Mt. Baker Stevens to Snoqualmie Pass Mt. Rainier Mt. Hood
Thursday Afternoon VAR 0 - 10 W 0 - 10 E 5 - 15 --- - E 10 - 20
Thursday Night VAR 0 - 10 VAR 0 - 10 E 5 - 15 --- - E 10 - 20
Friday Morning VAR 0 - 10 VAR 0 - 10 VAR 0 - 10 --- - W 5 - 15
Friday Afternoon SW 5 - 15 SW 10 - 20 W 10 - 20 --- - W 20 - 30
Hurricane Ridge Elevation
Thursday Afternoon VAR 0 - 10
Thursday Night VAR 0 - 10
Friday Morning VAR 0 - 10
Friday Afternoon SW 5 - 15
Friday Night VAR 0 - 10
Mt. Baker Elevation
Thursday Afternoon W 0 - 10
Thursday Night VAR 0 - 10
Friday Morning VAR 0 - 10
Friday Afternoon SW 10 - 20
Friday Night W 5 - 15
Stevens and Snoqualmie Pass Elevation
Thursday Afternoon E 5 - 15
Thursday Night E 5 - 15
Friday Morning VAR 0 - 10
Friday Afternoon W 10 - 20
Friday Night W 10 - 20
Mt. Rainier Elevation
Thursday Afternoon --- -
Thursday Night --- -
Friday Morning --- -
Friday Afternoon --- -
Friday Night --- -
Mt. Hood Elevation
Thursday Afternoon E 10 - 20
Thursday Night E 10 - 20
Friday Morning W 5 - 15
Friday Afternoon W 20 - 30
Friday Night W 15 - 25
Hurricane Ridge Direction - Speed
Thursday Afternoon VAR 0 - 10
Thursday Night VAR 0 - 10
Friday Morning VAR 0 - 10
Friday Afternoon SW 5 - 15
Friday Night VAR 0 - 10
Mt. Baker Direction - Speed
Thursday Afternoon W 0 - 10
Thursday Night VAR 0 - 10
Friday Morning VAR 0 - 10
Friday Afternoon SW 10 - 20
Friday Night W 5 - 15
Stevens and Snoqualmie Pass Direction - Speed
Thursday Afternoon E 5 - 15
Thursday Night E 5 - 15
Friday Morning VAR 0 - 10
Friday Afternoon W 10 - 20
Friday Night W 10 - 20
Mt. Rainier Direction - Speed
Thursday Afternoon --- -
Thursday Night --- -
Friday Morning --- -
Friday Afternoon --- -
Friday Night --- -
Mt. Hood Direction - Speed
Thursday Afternoon E 10 - 20
Thursday Night E 10 - 20
Friday Morning W 5 - 15
Friday Afternoon W 20 - 30
Friday Night W 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
Thursday Afternoon S 5 - 15 W 5 - 15 W 5 - 15 --- - S 10 - 20
Thursday Night VAR 0 - 10 VAR 0 - 10 VAR 0 - 10 --- - E 20 - 30
Friday Morning E 5 - 15 E 5 - 15 E 10 - 20 --- - E 20 - 30
Friday Afternoon E 5 - 15 VAR 0 - 10 E 15 - 25 --- - SSW 15 - 25
Mt. Baker Direction - Speed
Thursday Afternoon S 5 - 15
Thursday Night VAR 0 - 10
Friday Morning E 5 - 15
Friday Afternoon E 5 - 15
Friday Night ESE 5 - 15
Washington Pass Direction - Speed
Thursday Afternoon W 5 - 15
Thursday Night VAR 0 - 10
Friday Morning E 5 - 15
Friday Afternoon VAR 0 - 10
Friday Night E 10 - 20
Stevens and Snoqualmie Pass Direction - Speed
Thursday Afternoon W 5 - 15
Thursday Night VAR 0 - 10
Friday Morning E 10 - 20
Friday Afternoon E 15 - 25
Friday Night SSE 10 - 20
Mt. Rainier Direction - Speed
Thursday Afternoon --- -
Thursday Night --- -
Friday Morning --- -
Friday Afternoon --- -
Friday Night --- -
Mt. Hood Direction - Speed
Thursday Afternoon S 10 - 20
Thursday Night E 20 - 30
Friday Morning E 20 - 30
Friday Afternoon SSW 15 - 25
Friday Night SSW 10 - 20

Extended Weather Synopsis for Friday night through Friday

On Saturday, the upper low arrives onshore in central Oregon. The low will drift north across the Pacific Northwest through Sunday and then eastward by Monday. Saturday through Sunday morning, light rain and snow is forecast in bands that may persist in some areas for multiple hours as the bands move slowly northward. From mid-day Sunday through Monday, W-NW flow will bring light to occasionally moderate showers mainly to the west slopes of the Cascades, decreasing during the day on Monday. Snow levels will be near or below normal for the time of year. Winds are expected to be light to moderate out of the W or W-NW throughout most of the period.

Extended Weather

Olympics, Washington Cascades and Mt. Hood Area
Saturday Light to moderate periods of rain and snow in E-W oriented rain bands, particularly central and north Cascades and Olympics with light rain and snow east slopes of the Cascades, south Cascades and Olympics. Cooler to the south. Pattern continues Saturday night. Sunday Light to moderate rain and snow showers, mainly Cascade west slopes and Hood with convergence possible through Sunday night. Rain and snow decreasing Sunday night. Light W-NW flow. Monday Decreasing light showers along the west slopes of the Cascades and Hood.

Extended Snow/Freezing Levels

Mt. Baker Snoqualmie Pass Mt. Hood Easterly Flow *
Saturday Snow Level 6000' - 7000' 5000' - 7000' 4500' - 5500'
Saturday Night Snow Level 4000' - 5500' 4000' - 5000' 4000' - 5000'
Sunday Snow Level 4000' - 5000' 4000' - 5000' 4000' - 5000'
Sunday Night Snow Level 4000' - 5000' 3000' - 4000' 3000' - 4000'
Mt. Baker Elevation
Saturday Snow Level
6000' - 7000'
Saturday Night Snow Level
4000' - 5500'
Sunday Snow Level
4000' - 5000'
Sunday Night Snow Level
4000' - 5000'
Monday Snow Level
4000' - 5000'
Snoqualmie Pass Elevation
Saturday Snow Level
5000' - 7000'
Saturday Night Snow Level
4000' - 5000'
Sunday Snow Level
4000' - 5000'
Sunday Night Snow Level
3000' - 4000'
Monday Snow Level
3500' - 4500'
Mt. Hood Elevation
Saturday Snow Level
4500' - 5500'
Saturday Night Snow Level
4000' - 5000'
Sunday Snow Level
4000' - 5000'
Sunday Night Snow Level
3000' - 4000'
Monday Snow Level
3500' - 4500'

* 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 Apr 21, 2018

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.