Issued: 2:23 PM PST Monday, January 11, 2021
by Robert Hahn

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

Weather Synopsis

A major atmospheric river event is arriving in 3 waves. The first wave featured a cold front moving SE across northern Washington State on Monday, bringing heavy rain and snow. The second wave arrives as the E-W oriented tail of that cold front stalls over central Washington, bringing heavy rain and snow along with rising snow levels as it lifts back northward Monday night. The front should lift northward into Canada early Tuesday morning, leaving our region in the warm sector Tuesday as a relatively stationary front remains NW of our region, just off the Olympic peninsula, while heavy rain and high elevation snow pummel our mountains with heavy rain and high elevation snow. The third wave is the most impressive, with a very strong jetstream (190 mph!) as it approaches late Tuesday with some of the highest precipitation rates of the cycle Tuesday evening. A strong cold front passes WNW to ESE in the late evening hours brings relief from the deluge in the form of strong cooling along with moderate snow showers and strong convergence in it's wake. Wednesday should feature decreasing light snow showers and convergence with cold air continuing to move into the region on a brisk W flow with upper-level support. Strong ridgeline winds on the E slopes of the Cascades and through the lower mountain gaps should peak in the morning hours before decreasing. Very strong to extreme winds can be expected in favored areas such as the Wenatchee Mountains.

From Monday night through Tuesday night, our mountains can expect 2-8" of water equivalent, with the most likely at Paradise. 3000 ft snow levels in the passes Monday night will jump up early Tuesday, changing a rain/snow mix to all rain. This transition should happen later in the morning at Stevens Pass. Some areas could see 1-1.5 ft of additional snow before a changeover to rain at 3000-5000 ft elevations. Washington Pass is likely to pick up the most snow throughout this event with 4" of water equivalent expected as all snow, albeit heavy and dense!

Weather Forecast

Use dropdown to select your zone
Monday Night Increasing rain and high snow in the early evening becoming heavy.
Tuesday Heavy rain and high elevation snow in the morning becoming light to moderate in the afternoon.

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 1.00 - 1.50 0.50 - 0.75 0.75 -1.00 LT 0.10
Mt Baker Ski Area 1.50 - 2.00 1.00 - 1.50 1.00 - 1.50 0.25
Mt. Loop - Barlow Pass 1.50 - 2.00 2.00 2.00 0.25 - 0.50
Stevens Pass 1.00 1.00 - 1.50 1.50 0.25
Snoqualmie Pass 2.00 2.00 1.50 - 2.00 0.25
Crystal Mt 1.50 1.50 1.00 - 1.50 LT 0.25
Paradise 1.50 - 2.00 2.50 2.50 - 3.50 0.25
White Pass 0.75 -1.00 1.50 2.00 0.25
Washington Pass 1.00 - 1.50 1.50 1.50 0.25 - 0.50
Mission Ridge 0.50 - 0.75 0.50 - 0.75 0.50 LT 0.10
Salmon la Sac - Gallagher Head 1.00 - 1.50 1.50 1.00 - 1.50 0.25
Tieton River - Darland Mt. 0.75 1.00 1.00 LT 0.25
Mt Hood Meadows 0.75 1.50 - 2.00 2.50 - 3.50 0.25
Timberline 0.75 1.50 - 2.00 2.50 - 3.50 0.25
Hurricane Ridge Precipitation (in)
Monday Night 1.00 - 1.50
Tuesday 0.50 - 0.75
Tuesday Night 0.75 -1.00
Wednesday LT 0.10
Mt Baker Ski Area Precipitation (in)
Monday Night 1.50 - 2.00
Tuesday 1.00 - 1.50
Tuesday Night 1.00 - 1.50
Wednesday 0.25
Mt. Loop - Barlow Pass Precipitation (in)
Monday Night 1.50 - 2.00
Tuesday 2.00
Tuesday Night 2.00
Wednesday 0.25 - 0.50
Stevens Pass Precipitation (in)
Monday Night 1.00
Tuesday 1.00 - 1.50
Tuesday Night 1.50
Wednesday 0.25
Snoqualmie Pass Precipitation (in)
Monday Night 2.00
Tuesday 2.00
Tuesday Night 1.50 - 2.00
Wednesday 0.25
Crystal Mt Precipitation (in)
Monday Night 1.50
Tuesday 1.50
Tuesday Night 1.00 - 1.50
Wednesday LT 0.25
Paradise Precipitation (in)
Monday Night 1.50 - 2.00
Tuesday 2.50
Tuesday Night 2.50 - 3.50
Wednesday 0.25
White Pass Precipitation (in)
Monday Night 0.75 -1.00
Tuesday 1.50
Tuesday Night 2.00
Wednesday 0.25
Washington Pass Precipitation (in)
Monday Night 1.00 - 1.50
Tuesday 1.50
Tuesday Night 1.50
Wednesday 0.25 - 0.50
Mission Ridge Precipitation (in)
Monday Night 0.50 - 0.75
Tuesday 0.50 - 0.75
Tuesday Night 0.50
Wednesday LT 0.10
Salmon la Sac - Gallagher Head Precipitation (in)
Monday Night 1.00 - 1.50
Tuesday 1.50
Tuesday Night 1.00 - 1.50
Wednesday 0.25
Tieton River - Darland Mt. Precipitation (in)
Monday Night 0.75
Tuesday 1.00
Tuesday Night 1.00
Wednesday LT 0.25
Mt Hood Meadows Precipitation (in)
Monday Night 0.75
Tuesday 1.50 - 2.00
Tuesday Night 2.50 - 3.50
Wednesday 0.25
Timberline Precipitation (in)
Monday Night 0.75
Tuesday 1.50 - 2.00
Tuesday Night 2.50 - 3.50
Wednesday 0.25

Snow Level (ft)

Monday Evening * Monday Night * Tuesday Morning * Tuesday Afternoon * Tuesday Evening Tuesday Night Wednesday Morning Wednesday Afternoon
Olympics 4500' 6000' 6500' 6500' 6500' 4500' 2000' 2500'
West North 4000' 3500' 4500' 6000' 6500' 4500' 2000' 2000'
West Central 4000' 3500' 5000' 6500' 7000' 5500' 2500' 1500'
West South 4500' 5000' 6500' 6500' 7500' 6000' 2500' 2000'
Stevens Pass 3000' 2500' 3500' 6500' 7000' 5500' 2500' 2000'
Snoqualmie Pass 3000' 3500' 6000' 6500' 7500' 5500' 2500' 2000'
East North 3000' 2500' 2500' 4000' 6000' 5000' 2500' 2000'
East Central 3000' 3000' 4500' 6500' 7000' 6000' 3000' 2000'
East South 4500' 4500' 7000' 7000' 7500' 6500' 3000' 2500'
Mt. Hood 6500' 7500' 8000' 8500' 8000' 7000' 3500' 3000'
Olympics Elevation
Monday Evening * 4500'
Monday Night * 6000'
Tuesday Morning * 6500'
Tuesday Afternoon * 6500'
Tuesday Evening 6500'
Tuesday Night 4500'
Wednesday Morning 2000'
Wednesday Afternoon 2500'
West North Elevation
Monday Evening * 4000'
Monday Night * 3500'
Tuesday Morning * 4500'
Tuesday Afternoon * 6000'
Tuesday Evening 6500'
Tuesday Night 4500'
Wednesday Morning 2000'
Wednesday Afternoon 2000'
West Central Elevation
Monday Evening * 4000'
Monday Night * 3500'
Tuesday Morning * 5000'
Tuesday Afternoon * 6500'
Tuesday Evening 7000'
Tuesday Night 5500'
Wednesday Morning 2500'
Wednesday Afternoon 1500'
West South Elevation
Monday Evening * 4500'
Monday Night * 5000'
Tuesday Morning * 6500'
Tuesday Afternoon * 6500'
Tuesday Evening 7500'
Tuesday Night 6000'
Wednesday Morning 2500'
Wednesday Afternoon 2000'
Stevens Pass Elevation
Monday Evening * 3000'
Monday Night * 2500'
Tuesday Morning * 3500'
Tuesday Afternoon * 6500'
Tuesday Evening 7000'
Tuesday Night 5500'
Wednesday Morning 2500'
Wednesday Afternoon 2000'
Snoqualmie Pass Elevation
Monday Evening * 3000'
Monday Night * 3500'
Tuesday Morning * 6000'
Tuesday Afternoon * 6500'
Tuesday Evening 7500'
Tuesday Night 5500'
Wednesday Morning 2500'
Wednesday Afternoon 2000'
East North Elevation
Monday Evening * 3000'
Monday Night * 2500'
Tuesday Morning * 2500'
Tuesday Afternoon * 4000'
Tuesday Evening 6000'
Tuesday Night 5000'
Wednesday Morning 2500'
Wednesday Afternoon 2000'
East Central Elevation
Monday Evening * 3000'
Monday Night * 3000'
Tuesday Morning * 4500'
Tuesday Afternoon * 6500'
Tuesday Evening 7000'
Tuesday Night 6000'
Wednesday Morning 3000'
Wednesday Afternoon 2000'
East South Elevation
Monday Evening * 4500'
Monday Night * 4500'
Tuesday Morning * 7000'
Tuesday Afternoon * 7000'
Tuesday Evening 7500'
Tuesday Night 6500'
Wednesday Morning 3000'
Wednesday Afternoon 2500'
Mt. Hood Elevation
Monday Evening * 6500'
Monday Night * 7500'
Tuesday Morning * 8000'
Tuesday Afternoon * 8500'
Tuesday Evening 8000'
Tuesday Night 7000'
Wednesday Morning 3500'
Wednesday Afternoon 3000'

5000' Temperatures (°F)

Monday Night Tuesday
Max / Min Max / Min
Olympics 34 / 31 37 / 34
West North 31 / 29 34 / 30
West Central 31 / 29 35 / 32
West South 33 / 31 37 / 33
Stevens Pass 29 / 27 35 / 30
Snoqualmie Pass 31 / 28 36 / 32
East North 26 / 24 32 / 27
East Central 30 / 28 34 / 30
East South 33 / 30 36 / 32
Mt. Hood 37 / 33 41 / 35
Olympics 5000' Temperature Forecast
(Max / Min)
Monday 4pm - 4am 34 / 31
Tuesday 4am - 4pm 37 / 34
West North 5000' Temperature Forecast
(Max / Min)
Monday 4pm - 4am 31 / 29
Tuesday 4am - 4pm 34 / 30
West Central 5000' Temperature Forecast
(Max / Min)
Monday 4pm - 4am 31 / 29
Tuesday 4am - 4pm 35 / 32
West South 5000' Temperature Forecast
(Max / Min)
Monday 4pm - 4am 33 / 31
Tuesday 4am - 4pm 37 / 33
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Monday 4pm - 4am 29 / 27
Tuesday 4am - 4pm 35 / 30
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Monday 4pm - 4am 31 / 28
Tuesday 4am - 4pm 36 / 32
East North 5000' Temperature Forecast
(Max / Min)
Monday 4pm - 4am 26 / 24
Tuesday 4am - 4pm 32 / 27
East Central 5000' Temperature Forecast
(Max / Min)
Monday 4pm - 4am 30 / 28
Tuesday 4am - 4pm 34 / 30
East South 5000' Temperature Forecast
(Max / Min)
Monday 4pm - 4am 33 / 30
Tuesday 4am - 4pm 36 / 32
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Monday 4pm - 4am 37 / 33
Tuesday 4am - 4pm 41 / 35

Ridgeline Winds (mph)

Monday Evening Monday Night Tuesday Morning Tuesday Afternoon
Olympics SSW 20-30 SSW 20-30 SSW 5-15 SW 15-25
West North S 15-25 S 20-30 S 20-30 S 15-25
West Central S 10-20 SSE 10-20 SSW 15-25 SSW 15-25
West South SSW 20-30 SW 20-30 SSW 20-30 SW 20-30
Stevens Pass SSE 5-15 S 10-20 S 10-20 SW 10-20
Snoqualmie Pass SE 5-15 ESE 10-20 SSW 10-20 SSW 15-25
East North SSE 5-15 SSE 15-25 SSE 15-25 SW 20-30
East Central SSW 15-25 SSW 20-30 SSW 10-20 SW 15-25
East South S 15-25 SSW 15-25 SW 15-25 WSW 20-30
Mt. Hood SSW 20-30 SW 30-40 SW 25-35 WSW 35-50
Olympics Ridgeline Winds (mph)
Monday Evening SSW 20-30
Monday Night SSW 20-30
Tuesday Morning SSW 5-15
Tuesday Afternoon SW 15-25
West North Ridgeline Winds (mph)
Monday Evening S 15-25
Monday Night S 20-30
Tuesday Morning S 20-30
Tuesday Afternoon S 15-25
West Central Ridgeline Winds (mph)
Monday Evening S 10-20
Monday Night SSE 10-20
Tuesday Morning SSW 15-25
Tuesday Afternoon SSW 15-25
West South Ridgeline Winds (mph)
Monday Evening SSW 20-30
Monday Night SW 20-30
Tuesday Morning SSW 20-30
Tuesday Afternoon SW 20-30
Stevens Pass Ridgeline Winds (mph)
Monday Evening SSE 5-15
Monday Night S 10-20
Tuesday Morning S 10-20
Tuesday Afternoon SW 10-20
Snoqualmie Pass Ridgeline Winds (mph)
Monday Evening SE 5-15
Monday Night ESE 10-20
Tuesday Morning SSW 10-20
Tuesday Afternoon SSW 15-25
East North Ridgeline Winds (mph)
Monday Evening SSE 5-15
Monday Night SSE 15-25
Tuesday Morning SSE 15-25
Tuesday Afternoon SW 20-30
East Central Ridgeline Winds (mph)
Monday Evening SSW 15-25
Monday Night SSW 20-30
Tuesday Morning SSW 10-20
Tuesday Afternoon SW 15-25
East South Ridgeline Winds (mph)
Monday Evening S 15-25
Monday Night SSW 15-25
Tuesday Morning SW 15-25
Tuesday Afternoon WSW 20-30
Mt. Hood Ridgeline Winds (mph)
Monday Evening SSW 20-30
Monday Night SW 30-40
Tuesday Morning SW 25-35
Tuesday Afternoon WSW 35-50

Extended Weather Synopsis

The long-range brings relief from the very wet first half of the week. With cold air in place, Wednesday night could be quite cold as an amplifying ridge clears out the clouds and precipitation. Thursday, the ridge continues to amplify, leaving a mostly sunny day throughout the region with mild air moving in west of the Cascade Crest. A strong cold pool sits east of the Cascades, driving increasing moderate E flow at low levels. A weakening front approaches Thursday night and should bring some light rain and snow as it crosses the region through Friday morning, switching the low-level flow to westerly and a changeover from snow to rain at Snoqualmie Pass. A few rain and snow should linger Friday afternoon as weak ridging builds again offshore.

Extended Snow Level (ft)

Wednesday Night Thursday * Thursday Night * Friday
West North 500' 2000' 3500' 4500'
Snoqualmie Pass 1000' 2500' 3000' 5000'
Mt. Hood 3000' 7000' 8000' 7500'
West North Elevation
Wednesday Night 500'
Thursday * 2000'
Thursday Night * 3500'
Friday 4500'
Snoqualmie Pass Elevation
Wednesday Night 1000'
Thursday * 2500'
Thursday Night * 3000'
Friday 5000'
Mt. Hood Elevation
Wednesday Night 3000'
Thursday * 7000'
Thursday Night * 8000'
Friday 7500'

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

Previous forecast from Jan 11, 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’.