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
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
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.
Monday
Night
Increasing rain and high snow in the early evening becoming heavy to very heavy.
Tuesday
Heavy rain and high elevation snow.
Monday
Night
Increasing very heavy rain and snow.
Tuesday
Very eavy rain and high elevation snow.
Monday
Night
Decreasing rain and high elevation snow in the evening, then very heavy rain and high elevation snow overnight.
Tuesday
Very heavy rain and high elevation snow.
Monday
Night
Moderate rain and snow in the evening becoming heavy overnight. Light E winds at pass level.
Tuesday
Very heavy rain and high elevation snow. Light E winds at pass level.
Monday
Night
Increasing rain and snow in the evening becoming heavy to very heavy. Light to moderate E winds at pass level.
Tuesday
Very heavy rain and high elevation snow. Decreasing light E winds at pass level.
Monday
Night
Increasing moderate to heavy snow.
Tuesday
Heavy snow.
Monday
Night
Moderate rain and snow in the evening becoming heavy overnight.
Tuesday
Heavy rain and snow.
Monday
Night
Cloudy early, then increasing moderate to heavy rain and high elevation snow.
Tuesday
Heavy rain and snow.
Monday
Night
Increasing rain and snow in the evening becoming moderate to heavy overnight. Ridgeline winds becoming strong.
Tuesday
Very heavy rain and high elevation snow. Increasing strong to very strong ridgeline winds.
Issued: 2:23 PM PST Monday, January 11, 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
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
Issued: 2:23 PM PST Monday, January 11, 2021
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'
Issued: 2:23 PM PST Monday, January 11, 2021
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
Night
34 / 31
Tuesday
37 / 34
West North
5000' Temperature Forecast (Max / Min)
Monday
Night
31 / 29
Tuesday
34 / 30
West Central
5000' Temperature Forecast (Max / Min)
Monday
Night
31 / 29
Tuesday
35 / 32
West South
5000' Temperature Forecast (Max / Min)
Monday
Night
33 / 31
Tuesday
37 / 33
Stevens Pass
5000' Temperature Forecast (Max / Min)
Monday
Night
29 / 27
Tuesday
35 / 30
Snoqualmie Pass
5000' Temperature Forecast (Max / Min)
Monday
Night
31 / 28
Tuesday
36 / 32
East North
5000' Temperature Forecast (Max / Min)
Monday
Night
26 / 24
Tuesday
32 / 27
East Central
5000' Temperature Forecast (Max / Min)
Monday
Night
30 / 28
Tuesday
34 / 30
East South
5000' Temperature Forecast (Max / Min)
Monday
Night
33 / 30
Tuesday
36 / 32
Mt. Hood
5000' Temperature Forecast (Max / Min)
Monday
Night
37 / 33
Tuesday
41 / 35
Issued: 2:23 PM PST Monday, January 11, 2021
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
Issued: 2:23 PM PST Monday, January 11, 2021
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.
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).