Issued: 2:15 PM PST Monday, January 4, 2021
by Robert Hahn

Jump to: Weather Forecast I Precipitation I Snow Level I 5000' Temps I Ridgeline Winds I Extended Weather

Weather Synopsis

A moisture-laden cold front passed E to W through the Cascades Tuesday afternoon, leaving convergence focused on the mountain loop in its wake. The atmosphere will become more unstable as cooler air with the upper-level trough works its way into the region. The westerly flow will bring moderate, but locally intense scattered rain and snow showers along with convergence activity. High-resolution models indicate convergence activity shifting southward towards Stevens and Snoqualmie Passes during the evening hours. The convergence could reach Snoqualmie just around the time temperatures are cool enough for snow once again during the late evening hours.  Snow shower activity gradually eases later Monday night as temperatures continue to drop. Expect around 6 inches of snow for the west slopes of the Cascades above 3500 ft from the mountain loop southward, with 1-3" for other areas and Snoqualmie Pass at pass level.

Expect mostly cloudy skies with some very light snow Tuesday morning. Increasing light snow is likely to develop later in the day for both the west and east slopes of the Cascades. Southerly winds will focus moderate precipitation on Mt. Baker and the Olympics as a strong front approaches from the west along with winds increasing into the moderate to strong range. E flow through the mountain gaps should also increase.

Tuesday night, the strong front arrives with strong SSW flow bringing very windy conditions. Moderate E flow at pass level is likely to keep precipitation all snow at pass level. Upwards of 1 ft of snow is expected in many areas before precipitation tails off early Wednesday.

On Wednesday, an incoming trough tries to organize a circulation center that could bring some light precipitation to the Oregon Cascades.

Weather Forecast

Olympics
West North
West Central
West South
Stevens Pass
Snoqualmie Pass
East North
East Central
East South
Mt. Hood
Use dropdown to select your zone
Monday Night Mostly cloudy with a chance of light snow showers in the evening.
Tuesday Mostly cloudy with very light snow possible in the morning, then moderate snow in the afternoon.
Monday Night Moderate to locally intense snow showers in the evening becoming light.
Tuesday Periods of light snow in the morning, then moderate increasing to heavy snow in the afternoon.
Monday Night Moderate and locally intense snow showers and well-defined convergence, becoming light overnight.
Tuesday Periods of light snow increasing late in the day.
Monday Night Moderate and locally intense snow showers becoming light overnight.
Tuesday Periods of light snow increasing late in the day.
Monday Night Moderate snow showers locally intense in well-defined convergence, becoming light overnight. Decreasing light W winds at pass level.
Tuesday Periods of light snow increasing late in the day. Increasing light E wind at pass level.
Monday Night Moderate rain and snow showers changing to all snow at pass level by late evening. Showers locally intense in well-defined convergence, becoming light overnight. Decreasing light to moderate W winds at pass level.
Tuesday Periods of light snow increasing late in the day. Increasing light E wind at pass level becoming moderate in the afternoon.
Monday Night Light snow showers mainly near the Cascade Crest tapering off by the early morning hours.
Tuesday Mostly cloudy in the morning with light snow developing in the afternoon.
Monday Night Light snow showers mainly near the Cascade Crest tapering off by the early morning hours.
Tuesday Mostly cloudy in the morning with light snow developing in the afternoon.
Monday Night Light snow showers mainly near the Cascade Crest tapering off by the early morning hours.
Tuesday Mostly cloudy in the morning with a chance of light snow developing in the afternoon.
Monday Night Moderate and locally intense snow showers becoming light overnight.
Tuesday Mostly cloudy.

Issued: 2:15 PM PST Monday, January 4, 2021

Precipitation (in)

Monday Night Tuesday Tuesday Night Wednesday
4 pm - 4 am 4 am - 4 pm 4 pm - 4 am 4 am - 4 pm
Hurricane Ridge LT 0.25 0.50 - 0.75 0.75 -1.00 LT 0.10
Mt Baker Ski Area 0.25 0.50 - 0.75 1.50 LT 0.25
Mt. Loop - Barlow Pass 0.50 - 0.75 LT 0.25 1.00 - 1.50 LT 0.25
Stevens Pass 0.50 LT 0.10 0.75 LT 0.25
Snoqualmie Pass 0.50 - 0.75 LT 0.25 1.00 - 1.50 LT 0.10
Crystal Mt LT 0.25 LT 0.25 1.00 LT 0.10
Paradise 0.50 LT 0.25 1.50 0.25 - 0.50
White Pass 0.25 - 0.50 LT 0.10 0.50 LT 0.10
Washington Pass LT 0.25 LT 0.25 0.75 -1.00 LT 0.25
Mission Ridge LT 0.10 LT 0.10 0.25 LT 0.10
Salmon la Sac - Gallagher Head 0.25 LT 0.25 0.75 -1.00 LT 0.10
Tieton River - Darland Mt. 0.25 LT 0.10 0.25 - 0.50 LT 0.10
Mt Hood Meadows 0.50 LT 0.10 0.75 0.50 - 0.75
Timberline 0.50 LT 0.10 0.75 0.50 - 0.75
Hurricane Ridge Precipitation (in)
Monday Night LT 0.25
Tuesday 0.50 - 0.75
Tuesday Night 0.75 -1.00
Wednesday LT 0.10
Mt Baker Ski Area Precipitation (in)
Monday Night 0.25
Tuesday 0.50 - 0.75
Tuesday Night 1.50
Wednesday LT 0.25
Mt. Loop - Barlow Pass Precipitation (in)
Monday Night 0.50 - 0.75
Tuesday LT 0.25
Tuesday Night 1.00 - 1.50
Wednesday LT 0.25
Stevens Pass Precipitation (in)
Monday Night 0.50
Tuesday LT 0.10
Tuesday Night 0.75
Wednesday LT 0.25
Snoqualmie Pass Precipitation (in)
Monday Night 0.50 - 0.75
Tuesday LT 0.25
Tuesday Night 1.00 - 1.50
Wednesday LT 0.10
Crystal Mt Precipitation (in)
Monday Night LT 0.25
Tuesday LT 0.25
Tuesday Night 1.00
Wednesday LT 0.10
Paradise Precipitation (in)
Monday Night 0.50
Tuesday LT 0.25
Tuesday Night 1.50
Wednesday 0.25 - 0.50
White Pass Precipitation (in)
Monday Night 0.25 - 0.50
Tuesday LT 0.10
Tuesday Night 0.50
Wednesday LT 0.10
Washington Pass Precipitation (in)
Monday Night LT 0.25
Tuesday LT 0.25
Tuesday Night 0.75 -1.00
Wednesday LT 0.25
Mission Ridge Precipitation (in)
Monday Night LT 0.10
Tuesday LT 0.10
Tuesday Night 0.25
Wednesday LT 0.10
Salmon la Sac - Gallagher Head Precipitation (in)
Monday Night 0.25
Tuesday LT 0.25
Tuesday Night 0.75 -1.00
Wednesday LT 0.10
Tieton River - Darland Mt. Precipitation (in)
Monday Night 0.25
Tuesday LT 0.10
Tuesday Night 0.25 - 0.50
Wednesday LT 0.10
Mt Hood Meadows Precipitation (in)
Monday Night 0.50
Tuesday LT 0.10
Tuesday Night 0.75
Wednesday 0.50 - 0.75
Timberline Precipitation (in)
Monday Night 0.50
Tuesday LT 0.10
Tuesday Night 0.75
Wednesday 0.50 - 0.75

Issued: 2:15 PM PST Monday, January 4, 2021

Snow Level (ft)

Monday Evening Monday Night Tuesday Morning* Tuesday Afternoon* Tuesday Evening* Tuesday Night* Wednesday Morning* Wednesday Afternoon*
Olympics 3000' 1500' 2000' 3000' 3000' 3500' 2500' 3500'
West North 2500' 2000' 1500' 2500' 2500' 2500' 2500' 3000'
West Central 3000' 2000' 1500' 2500' 2500' 2000' 2500' 3000'
West South 3000' 2000' 1500' 3000' 3500' 3500' 3500' 4000'
Stevens Pass 3000' 2000' 1500' 3000' 2500' 2000' 2500' 3500'
Snoqualmie Pass 3000' 2500' 2000' 3000' 2500' 2500' 2500' 3500'
East North 3000' 2000' 500' 2000' 2000' 1500' 2000' 3000'
East Central 3000' 2000' 1000' 2500' 2500' 2500' 2500' 3500'
East South 3000' 2500' 2000' 3000' 3500' 3500' 3500' 4000'
Mt. Hood 3000' 3000' 2000' 4000' 6000' 4500' 5000' 4500'
Olympics Elevation
Monday Evening 3000'
Monday Night 1500'
Tuesday Morning* 2000'
Tuesday Afternoon* 3000'
Tuesday Evening* 3000'
Tuesday Night* 3500'
Wednesday Morning* 2500'
Wednesday Afternoon* 3500'
West North Elevation
Monday Evening 2500'
Monday Night 2000'
Tuesday Morning* 1500'
Tuesday Afternoon* 2500'
Tuesday Evening* 2500'
Tuesday Night* 2500'
Wednesday Morning* 2500'
Wednesday Afternoon* 3000'
West Central Elevation
Monday Evening 3000'
Monday Night 2000'
Tuesday Morning* 1500'
Tuesday Afternoon* 2500'
Tuesday Evening* 2500'
Tuesday Night* 2000'
Wednesday Morning* 2500'
Wednesday Afternoon* 3000'
West South Elevation
Monday Evening 3000'
Monday Night 2000'
Tuesday Morning* 1500'
Tuesday Afternoon* 3000'
Tuesday Evening* 3500'
Tuesday Night* 3500'
Wednesday Morning* 3500'
Wednesday Afternoon* 4000'
Stevens Pass Elevation
Monday Evening 3000'
Monday Night 2000'
Tuesday Morning* 1500'
Tuesday Afternoon* 3000'
Tuesday Evening* 2500'
Tuesday Night* 2000'
Wednesday Morning* 2500'
Wednesday Afternoon* 3500'
Snoqualmie Pass Elevation
Monday Evening 3000'
Monday Night 2500'
Tuesday Morning* 2000'
Tuesday Afternoon* 3000'
Tuesday Evening* 2500'
Tuesday Night* 2500'
Wednesday Morning* 2500'
Wednesday Afternoon* 3500'
East North Elevation
Monday Evening 3000'
Monday Night 2000'
Tuesday Morning* 500'
Tuesday Afternoon* 2000'
Tuesday Evening* 2000'
Tuesday Night* 1500'
Wednesday Morning* 2000'
Wednesday Afternoon* 3000'
East Central Elevation
Monday Evening 3000'
Monday Night 2000'
Tuesday Morning* 1000'
Tuesday Afternoon* 2500'
Tuesday Evening* 2500'
Tuesday Night* 2500'
Wednesday Morning* 2500'
Wednesday Afternoon* 3500'
East South Elevation
Monday Evening 3000'
Monday Night 2500'
Tuesday Morning* 2000'
Tuesday Afternoon* 3000'
Tuesday Evening* 3500'
Tuesday Night* 3500'
Wednesday Morning* 3500'
Wednesday Afternoon* 4000'
Mt. Hood Elevation
Monday Evening 3000'
Monday Night 3000'
Tuesday Morning* 2000'
Tuesday Afternoon* 4000'
Tuesday Evening* 6000'
Tuesday Night* 4500'
Wednesday Morning* 5000'
Wednesday Afternoon* 4500'

Issued: 2:15 PM PST Monday, January 4, 2021

5000' Temperatures (°F)

Monday Night Tuesday
Max / Min Max / Min
Olympics 26 / 22 27 / 23
West North 26 / 21 25 / 21
West Central 26 / 21 25 / 22
West South 27 / 22 27 / 23
Stevens Pass 27 / 20 26 / 21
Snoqualmie Pass 27 / 21 26 / 21
East North 28 / 17 24 / 18
East Central 28 / 20 26 / 20
East South 28 / 20 27 / 20
Mt. Hood 27 / 24 33 / 24
Olympics 5000' Temperature Forecast
(Max / Min)
Monday Night 26 / 22
Tuesday 27 / 23
West North 5000' Temperature Forecast
(Max / Min)
Monday Night 26 / 21
Tuesday 25 / 21
West Central 5000' Temperature Forecast
(Max / Min)
Monday Night 26 / 21
Tuesday 25 / 22
West South 5000' Temperature Forecast
(Max / Min)
Monday Night 27 / 22
Tuesday 27 / 23
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Monday Night 27 / 20
Tuesday 26 / 21
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Monday Night 27 / 21
Tuesday 26 / 21
East North 5000' Temperature Forecast
(Max / Min)
Monday Night 28 / 17
Tuesday 24 / 18
East Central 5000' Temperature Forecast
(Max / Min)
Monday Night 28 / 20
Tuesday 26 / 20
East South 5000' Temperature Forecast
(Max / Min)
Monday Night 28 / 20
Tuesday 27 / 20
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Monday Night 27 / 24
Tuesday 33 / 24

Issued: 2:15 PM PST Monday, January 4, 2021

Ridgeline Winds (mph)

Monday Evening Monday Night Tuesday Morning Tuesday Afternoon
Olympics WSW 5-15 SW 10-20 S 15-25 S 20-30
West North W 10-20 WSW 5-15 SSE 15-25 SSE 25-35
West Central WNW 10-20 WSW 10-20 S 10-20 SSE 15-25
West South W 15-25 W 5-15 S 5-15 SSE 15-25
Stevens Pass W 10-20 W 5-15 VAR 0-10 ESE 15-25
Snoqualmie Pass WNW 15-25 W 10-20 VAR 0-10 ESE 5-15
East North WNW 20-30 W 15-25 SSW 0-10 SE 10-20
East Central W 25-35 W 20-30 WSW 5-15 ESE 10-20
East South W 25-35 W 20-30 SSW 5-15 SSE 10-20
Mt. Hood WSW 20-30 WSW 20-30 SSW 10-20 SSW 15-25
Olympics Ridgeline Winds (mph)
Monday Evening WSW 5-15
Monday Night SW 10-20
Tuesday Morning S 15-25
Tuesday Afternoon S 20-30
West North Ridgeline Winds (mph)
Monday Evening W 10-20
Monday Night WSW 5-15
Tuesday Morning SSE 15-25
Tuesday Afternoon SSE 25-35
West Central Ridgeline Winds (mph)
Monday Evening WNW 10-20
Monday Night WSW 10-20
Tuesday Morning S 10-20
Tuesday Afternoon SSE 15-25
West South Ridgeline Winds (mph)
Monday Evening W 15-25
Monday Night W 5-15
Tuesday Morning S 5-15
Tuesday Afternoon SSE 15-25
Stevens Pass Ridgeline Winds (mph)
Monday Evening W 10-20
Monday Night W 5-15
Tuesday Morning VAR 0-10
Tuesday Afternoon ESE 15-25
Snoqualmie Pass Ridgeline Winds (mph)
Monday Evening WNW 15-25
Monday Night W 10-20
Tuesday Morning VAR 0-10
Tuesday Afternoon ESE 5-15
East North Ridgeline Winds (mph)
Monday Evening WNW 20-30
Monday Night W 15-25
Tuesday Morning SSW 0-10
Tuesday Afternoon SE 10-20
East Central Ridgeline Winds (mph)
Monday Evening W 25-35
Monday Night W 20-30
Tuesday Morning WSW 5-15
Tuesday Afternoon ESE 10-20
East South Ridgeline Winds (mph)
Monday Evening W 25-35
Monday Night W 20-30
Tuesday Morning SSW 5-15
Tuesday Afternoon SSE 10-20
Mt. Hood Ridgeline Winds (mph)
Monday Evening WSW 20-30
Monday Night WSW 20-30
Tuesday Morning SSW 10-20
Tuesday Afternoon SSW 15-25

Issued: 2:15 PM PST Monday, January 4, 2021

Extended Weather Synopsis

A trough providing some cooler weather and light showers Wednesday evening should be replaced by a shortwave ridge overnight, making for gradually clearing skies. The ridge amplifies over the region on Thursday, proving a mostly sunny day. The ridge shifts east Thursday night, with low-level E flow and mid-level cloud cover increasing ahead of a weakening trough that is slated to bring some light rain and snow on Friday.

Extended Snow Level (ft)

Wednesday Night* Thursday * Thursday Night* Friday *
West North 1500' 2500' 2000' 1500'
Snoqualmie Pass 2500' 3000' 2500' 2000'
Mt. Hood 3500' 4000' 3500' 3000'
West North Elevation
Wednesday Night* 1500'
Thursday * 2500'
Thursday Night* 2000'
Friday * 1500'
Snoqualmie Pass Elevation
Wednesday Night* 2500'
Thursday * 3000'
Thursday Night* 2500'
Friday * 2000'
Mt. Hood Elevation
Wednesday Night* 3500'
Thursday * 4000'
Thursday Night* 3500'
Friday * 3000'

Jump to: Weather Forecast I Precipitation I Snow Level I 5000' Temps I Ridgeline Winds I Extended Weather

Previous forecast from Jan 4, 2021

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.

The 5000’ temperature forecast does not imply a trend over the 12 hr period and only represents the max and min temperatures within a 12 hr period in the zone. The 6-hr snow level forecast, the forecast discussion, and weather forecast sections may add detail regarding temperature trends.

The snow level forecast represents the general snow level over a 6 hr time period. Freezing levels are forecast when precipitation is not expected.

*Easterly or offshore flow is highlighted with an asterisk when we expect relatively cool east winds in the major Cascade Passes. Easterly flow will often lead to temperature inversions and is a key variable for forecasting precipitation type in the Cascade Passes. Strong easterly flow events can affect terrain on a more regional scale.

Ridgeline winds are the average wind speed and direction over a 6 hr time period.

The wind forecast represents an elevation range instead of a single elevation slice. The elevation range overlaps with the near and above treeline elevation bands in the avalanche forecast and differs per zone.

Wind direction indicates the direction the wind originates or comes from on the 16-point compass rose.

Water Equivalent (WE) is the liquid water equivalent of all precipitation types; rain, snow, ice pellets, etc., forecast to the hundredth of an inch at specific locations. To use WE as a proxy for snowfall amounts, start with a snow to water ratio of 10:1 (10 inches of snow = 1 inch WE). Temperatures at or near freezing will generally have a lower ratio (heavy wet snow) and very cold temperatures can have a much higher ratio (dry fluffy snow).

The label LT, is shorthand for ‘less than’.