Jump to: Weather Forecast I Precipitation I Snow Level I 5000' Temps I Ridgeline Winds I Extended Weather
Weather Synopsis
A compact low formed along the subtropical feed of moisture and approaches the region Sunday night. The front stalled over northern Oregon on Sunday lifts back northward as a fairly strong warm front, spreading a band of moderate rain and snow along with sharply increasing temperatures back into Washington State. WSW winds across the region will increase into the strong range in the alpine, but low-level winds through the mountain gaps should shift easterly Sunday evening through noon on Monday. Without much cold air to work with, expect Snoqualmie Pass to start as a rain/snow mix before warmer air aloft overwhelms the cooler easterly flow. Stevens Pass may pick up 2-3 inches of snow before changing to rain.
The significant snowfall will occur on the colder northern and western flanks of the low as it tracks E to W across the Olympic mountains and the central Cascades on Monday. Models show general agreement for heavy snowfall throughout the North Cascades from late Sunday night through mid-day Monday with the band pivoting to a N-S behind a strong cold front passing early Monday afternoon and re-orientating precipitation to focus on the entire W slopes of the Cascades. The strong front should bring in significantly colder on a W or WNW flow. A major upslope snowfall event is also likely the northern Olympic Mountains, where the track of the low sucks colder air from the north up the slopes of the Olympics. The setup has the potential to bring snow down to sea-level, while the southern portions of the Olympics may see concurrent 5000-6000 ft snow levels before cooler air works in behind the front. In the warmer dry sector, expect significantly lighter precipitation, elevated snow levels and very strong alpine winds.
Flow switches NW and remains strong Monday night. Snow shower activity decreases Monday night from the moderate range in the evening to the light range overnight. Some banded showers may be locally intense with snow levels dropping well below pass level by midnight.
Snow forecast amounts are tricky with this system. From late Sunday night through Monday night we expect 15-20" for Washington Pass and Hurricane Ridge, 12-18" for Mt Baker, 6-10" for Stevens Pass, and 3-6" for Snoqualmie Pass (mostly after the rain event).
On Tuesday, very light snow showers will linger in a few areas, but most areas will start to see some partly cloudy skies.
Weather Forecast
| Sunday Night | Light rain and snow developing in the evening, becoming moderate overnight. |
|---|---|
| Monday | Heavy upslope snowfall. Colder. Strong winds. |
| Sunday Night | Light rain and snow showers becoming with steady rain and snow increasing after midnight. |
|---|---|
| Monday | Heavy rain and snow (mostly snow) developing and peaking in the mid-day hour. Strong winds in the afternoon. |
| Sunday Night | Light rain and snow showers becoming with steady rain and snow increasing after midnight. |
|---|---|
| Monday | Heavy rain and high elevation snow. Strong winds. |
| Sunday Night | Heavy rain and high elevation snow at Paradise, moderate at White Pass, and light at Crystal. |
|---|---|
| Monday | Heavy rain and high elevation snow at Paradise, moderate at White Pass, and light at Crystal. Strong winds. |
| Sunday Night | Light rain and snow showers becoming with steady moderate rain and snow developing after midnight. Light W winds shifting E at pass level overnight. |
|---|---|
| Monday | Moderate rain and snow. Strong ridgeline winds. E winds at pass level shifting to moderate W in the afternoon. |
| Sunday Night | Light rain and snow showers becoming with steady moderate rain and snow developing after midnight. Light W winds shifting E at pass level overnight. |
|---|---|
| Monday | Moderate rain and snow. Strong ridgeline winds. E winds at pass level shifting to moderate W in the afternoon. |
| Sunday Night | Increasing light snow becoming moderate then heavy after midnight. |
|---|---|
| Monday | Very heavy snow through early afternoon, then decreasing. Strong wind gusts. |
| Sunday Night | Light rain and snow becoming moderate to heavy at times after midnight. |
|---|---|
| Monday | Moderate rain and snow. Moderate winds becoming strong. |
| Sunday Night | Moderate rain and high elevation snow. |
|---|---|
| Monday | Moderate rain and snow. Moderate winds becoming strong. |
| Sunday Night | Very heavy rain and high elevation snow. Mild. Strong to very strong ridgeline winds. |
|---|---|
| Monday | Moderate rain and high elevation snow. Strong winds. |
Issued: 2:19 PM PST Sunday, December 20, 2020
Precipitation (in)
| Sunday Night | Monday | Monday Night | Tuesday | |
|---|---|---|---|---|
| 4 pm - 4 am | 4 am - 4 pm | 4 pm - 4 am | 4 am - 4 pm | |
| Hurricane Ridge | 0.50 | 1.50 | 0 | 0 |
| Mt Baker Ski Area | 0.25 | 1.00 - 1.50 | LT 0.25 | 0 |
| Mt. Loop - Barlow Pass | 0.25 - 0.50 | 1.50 | 0.25 - 0.50 | 0 |
| Stevens Pass | 0.50 | 0.75 | 0.25 - 0.50 | 0 |
| Snoqualmie Pass | 0.50 - 0.75 | 0.75 -1.00 | LT 0.25 | 0 |
| Crystal Mt | 0.25 - 0.50 | 0.50 - 0.75 | 0.25 | 0 |
| Paradise | 1.50 | 1.50 | LT 0.25 | 0 |
| White Pass | 0.75 | 0.50 | LT 0.25 | 0 |
| Washington Pass | 0.25 - 0.50 | 1.00 - 1.50 | LT 0.25 | 0 |
| Mission Ridge | 0.25 - 0.50 | 0.25 - 0.50 | LT 0.10 | 0 |
| Salmon la Sac - Gallagher Head | 0.50 | 0.50 - 0.75 | 0.25 | LT 0.10 |
| Tieton River - Darland Mt. | 0.50 - 0.75 | 0.50 | LT 0.25 | 0 |
| Mt Hood Meadows | 2.00 | 0.50 - 0.75 | 0.50 - 0.75 | LT 0.10 |
| Timberline | 2.00 | 0.50 - 0.75 | 0.75 | LT 0.10 |
| Hurricane Ridge | Precipitation (in) |
|---|---|
| Sunday Night | 0.50 |
| Monday | 1.50 |
| Monday Night | 0 |
| Tuesday | 0 |
| Mt Baker Ski Area | Precipitation (in) |
|---|---|
| Sunday Night | 0.25 |
| Monday | 1.00 - 1.50 |
| Monday Night | LT 0.25 |
| Tuesday | 0 |
| Mt. Loop - Barlow Pass | Precipitation (in) |
|---|---|
| Sunday Night | 0.25 - 0.50 |
| Monday | 1.50 |
| Monday Night | 0.25 - 0.50 |
| Tuesday | 0 |
| Stevens Pass | Precipitation (in) |
|---|---|
| Sunday Night | 0.50 |
| Monday | 0.75 |
| Monday Night | 0.25 - 0.50 |
| Tuesday | 0 |
| Snoqualmie Pass | Precipitation (in) |
|---|---|
| Sunday Night | 0.50 - 0.75 |
| Monday | 0.75 -1.00 |
| Monday Night | LT 0.25 |
| Tuesday | 0 |
| Crystal Mt | Precipitation (in) |
|---|---|
| Sunday Night | 0.25 - 0.50 |
| Monday | 0.50 - 0.75 |
| Monday Night | 0.25 |
| Tuesday | 0 |
| Paradise | Precipitation (in) |
|---|---|
| Sunday Night | 1.50 |
| Monday | 1.50 |
| Monday Night | LT 0.25 |
| Tuesday | 0 |
| White Pass | Precipitation (in) |
|---|---|
| Sunday Night | 0.75 |
| Monday | 0.50 |
| Monday Night | LT 0.25 |
| Tuesday | 0 |
| Washington Pass | Precipitation (in) |
|---|---|
| Sunday Night | 0.25 - 0.50 |
| Monday | 1.00 - 1.50 |
| Monday Night | LT 0.25 |
| Tuesday | 0 |
| Mission Ridge | Precipitation (in) |
|---|---|
| Sunday Night | 0.25 - 0.50 |
| Monday | 0.25 - 0.50 |
| Monday Night | LT 0.10 |
| Tuesday | 0 |
| Salmon la Sac - Gallagher Head | Precipitation (in) |
|---|---|
| Sunday Night | 0.50 |
| Monday | 0.50 - 0.75 |
| Monday Night | 0.25 |
| Tuesday | LT 0.10 |
| Tieton River - Darland Mt. | Precipitation (in) |
|---|---|
| Sunday Night | 0.50 - 0.75 |
| Monday | 0.50 |
| Monday Night | LT 0.25 |
| Tuesday | 0 |
| Mt Hood Meadows | Precipitation (in) |
|---|---|
| Sunday Night | 2.00 |
| Monday | 0.50 - 0.75 |
| Monday Night | 0.50 - 0.75 |
| Tuesday | LT 0.10 |
| Timberline | Precipitation (in) |
|---|---|
| Sunday Night | 2.00 |
| Monday | 0.50 - 0.75 |
| Monday Night | 0.75 |
| Tuesday | LT 0.10 |
Issued: 2:19 PM PST Sunday, December 20, 2020
Snow Level (ft)
| Sunday Evening | Sunday Night* | Monday Morning* | Monday Afternoon | Monday Evening | Monday Night | Tuesday Morning | Tuesday Afternoon | |
|---|---|---|---|---|---|---|---|---|
| Olympics | 3500' | 4000' | 3500' | 3000' | 1500' | 1500' | 1000' | 2000' |
| West North | 3500' | 3000' | 3000' | 3000' | 2000' | 1000' | 1000' | 1000' |
| West Central | 3500' | 4000' | 5000' | 5000' | 3000' | 1500' | 1000' | 1500' |
| West South | 4500' | 5500' | 6500' | 6000' | 4000' | 1500' | 1000' | 1500' |
| Stevens Pass | 3500' | 3500' | 5000' | 5500' | 3500' | 1500' | 1000' | 1500' |
| Snoqualmie Pass | 4000' | 4000' | 6000' | 6000' | 3500' | 2000' | 1000' | 1500' |
| East North | 3000' | 2500' | 3000' | 3500' | 3000' | 1500' | 500' | 1000' |
| East Central | 4000' | 4000' | 6000' | 6000' | 3500' | 1500' | 1000' | 1500' |
| East South | 5500' | 6500' | 6500' | 6000' | 4000' | 2000' | 1500' | 2000' |
| Mt. Hood | 7500' | 8000' | 7000' | 6500' | 4000' | 2000' | 2000' | 2000' |
| Olympics | Elevation |
|---|---|
| Sunday Evening | 3500' |
| Sunday Night* | 4000' |
| Monday Morning* | 3500' |
| Monday Afternoon | 3000' |
| Monday Evening | 1500' |
| Monday Night | 1500' |
| Tuesday Morning | 1000' |
| Tuesday Afternoon | 2000' |
| West North | Elevation |
|---|---|
| Sunday Evening | 3500' |
| Sunday Night* | 3000' |
| Monday Morning* | 3000' |
| Monday Afternoon | 3000' |
| Monday Evening | 2000' |
| Monday Night | 1000' |
| Tuesday Morning | 1000' |
| Tuesday Afternoon | 1000' |
| West Central | Elevation |
|---|---|
| Sunday Evening | 3500' |
| Sunday Night* | 4000' |
| Monday Morning* | 5000' |
| Monday Afternoon | 5000' |
| Monday Evening | 3000' |
| Monday Night | 1500' |
| Tuesday Morning | 1000' |
| Tuesday Afternoon | 1500' |
| West South | Elevation |
|---|---|
| Sunday Evening | 4500' |
| Sunday Night* | 5500' |
| Monday Morning* | 6500' |
| Monday Afternoon | 6000' |
| Monday Evening | 4000' |
| Monday Night | 1500' |
| Tuesday Morning | 1000' |
| Tuesday Afternoon | 1500' |
| Stevens Pass | Elevation |
|---|---|
| Sunday Evening | 3500' |
| Sunday Night* | 3500' |
| Monday Morning* | 5000' |
| Monday Afternoon | 5500' |
| Monday Evening | 3500' |
| Monday Night | 1500' |
| Tuesday Morning | 1000' |
| Tuesday Afternoon | 1500' |
| Snoqualmie Pass | Elevation |
|---|---|
| Sunday Evening | 4000' |
| Sunday Night* | 4000' |
| Monday Morning* | 6000' |
| Monday Afternoon | 6000' |
| Monday Evening | 3500' |
| Monday Night | 2000' |
| Tuesday Morning | 1000' |
| Tuesday Afternoon | 1500' |
| East North | Elevation |
|---|---|
| Sunday Evening | 3000' |
| Sunday Night* | 2500' |
| Monday Morning* | 3000' |
| Monday Afternoon | 3500' |
| Monday Evening | 3000' |
| Monday Night | 1500' |
| Tuesday Morning | 500' |
| Tuesday Afternoon | 1000' |
| East Central | Elevation |
|---|---|
| Sunday Evening | 4000' |
| Sunday Night* | 4000' |
| Monday Morning* | 6000' |
| Monday Afternoon | 6000' |
| Monday Evening | 3500' |
| Monday Night | 1500' |
| Tuesday Morning | 1000' |
| Tuesday Afternoon | 1500' |
| East South | Elevation |
|---|---|
| Sunday Evening | 5500' |
| Sunday Night* | 6500' |
| Monday Morning* | 6500' |
| Monday Afternoon | 6000' |
| Monday Evening | 4000' |
| Monday Night | 2000' |
| Tuesday Morning | 1500' |
| Tuesday Afternoon | 2000' |
| Mt. Hood | Elevation |
|---|---|
| Sunday Evening | 7500' |
| Sunday Night* | 8000' |
| Monday Morning* | 7000' |
| Monday Afternoon | 6500' |
| Monday Evening | 4000' |
| Monday Night | 2000' |
| Tuesday Morning | 2000' |
| Tuesday Afternoon | 2000' |
Issued: 2:19 PM PST Sunday, December 20, 2020
5000' Temperatures (°F)
| Sunday Night | Monday | ||
|---|---|---|---|
| Max / Min | Max / Min | ||
| Olympics | 28 / 26 | 29 / 25 | |
| West North | 28 / 23 | 30 / 24 | |
| West Central | 31 / 26 | 35 / 26 | |
| West South | 38 / 30 | 36 / 28 | |
| Stevens Pass | 31 / 26 | 33 / 26 | |
| Snoqualmie Pass | 34 / 26 | 35 / 27 | |
| East North | 27 / 25 | 30 / 25 | |
| East Central | 32 / 26 | 33 / 27 | |
| East South | 38 / 29 | 36 / 28 | |
| Mt. Hood | 40 / 38 | 40 / 35 |
| Olympics | 5000' Temperature Forecast (Max / Min) |
|---|---|
| Sunday Night | 28 / 26 |
| Monday | 29 / 25 |
| West North | 5000' Temperature Forecast (Max / Min) |
|---|---|
| Sunday Night | 28 / 23 |
| Monday | 30 / 24 |
| West Central | 5000' Temperature Forecast (Max / Min) |
|---|---|
| Sunday Night | 31 / 26 |
| Monday | 35 / 26 |
| West South | 5000' Temperature Forecast (Max / Min) |
|---|---|
| Sunday Night | 38 / 30 |
| Monday | 36 / 28 |
| Stevens Pass | 5000' Temperature Forecast (Max / Min) |
|---|---|
| Sunday Night | 31 / 26 |
| Monday | 33 / 26 |
| Snoqualmie Pass | 5000' Temperature Forecast (Max / Min) |
|---|---|
| Sunday Night | 34 / 26 |
| Monday | 35 / 27 |
| East North | 5000' Temperature Forecast (Max / Min) |
|---|---|
| Sunday Night | 27 / 25 |
| Monday | 30 / 25 |
| East Central | 5000' Temperature Forecast (Max / Min) |
|---|---|
| Sunday Night | 32 / 26 |
| Monday | 33 / 27 |
| East South | 5000' Temperature Forecast (Max / Min) |
|---|---|
| Sunday Night | 38 / 29 |
| Monday | 36 / 28 |
| Mt. Hood | 5000' Temperature Forecast (Max / Min) |
|---|---|
| Sunday Night | 40 / 38 |
| Monday | 40 / 35 |
Issued: 2:19 PM PST Sunday, December 20, 2020
Ridgeline Winds (mph)
| Sunday Evening | Sunday Night | Monday Morning | Monday Afternoon | |
|---|---|---|---|---|
| Olympics | SE 0-10 | SSE 0-10 | SW 20-30 | W 20-30 |
| West North | WSW 5-15 | ENE 0-10 | ESE 10-20 | W 25-35 |
| West Central | W 5-15 | S 5-15 | SW 25-35 | W 25-35 |
| West South | SW 5-15 | SW 20-30 | SW 25-35 | W 25-35 |
| Stevens Pass | W 5-15 | SSW 5-15 | WSW 25-35 | WSW 25-35 |
| Snoqualmie Pass | WNW 5-15 | SSW 5-15 | WSW 25-35 | W 25-35 |
| East North | WSW 5-15 | ESE 0-10 | SE 15-25 | W 20-30 |
| East Central | W 5-15 | SW 15-25 | S 25-35 | WSW 25-35 |
| East South | WSW 5-15 | WSW 20-30 | WSW 20-30 | WSW 25-35 |
| Mt. Hood | WSW 25-35 | WSW 30-40 | WSW 30-40 | WSW 35-50 |
| Olympics | Ridgeline Winds (mph) |
|---|---|
| Sunday Evening | SE 0-10 |
| Sunday Night | SSE 0-10 |
| Monday Morning | SW 20-30 |
| Monday Afternoon | W 20-30 |
| West North | Ridgeline Winds (mph) |
|---|---|
| Sunday Evening | WSW 5-15 |
| Sunday Night | ENE 0-10 |
| Monday Morning | ESE 10-20 |
| Monday Afternoon | W 25-35 |
| West Central | Ridgeline Winds (mph) |
|---|---|
| Sunday Evening | W 5-15 |
| Sunday Night | S 5-15 |
| Monday Morning | SW 25-35 |
| Monday Afternoon | W 25-35 |
| West South | Ridgeline Winds (mph) |
|---|---|
| Sunday Evening | SW 5-15 |
| Sunday Night | SW 20-30 |
| Monday Morning | SW 25-35 |
| Monday Afternoon | W 25-35 |
| Stevens Pass | Ridgeline Winds (mph) |
|---|---|
| Sunday Evening | W 5-15 |
| Sunday Night | SSW 5-15 |
| Monday Morning | WSW 25-35 |
| Monday Afternoon | WSW 25-35 |
| Snoqualmie Pass | Ridgeline Winds (mph) |
|---|---|
| Sunday Evening | WNW 5-15 |
| Sunday Night | SSW 5-15 |
| Monday Morning | WSW 25-35 |
| Monday Afternoon | W 25-35 |
| East North | Ridgeline Winds (mph) |
|---|---|
| Sunday Evening | WSW 5-15 |
| Sunday Night | ESE 0-10 |
| Monday Morning | SE 15-25 |
| Monday Afternoon | W 20-30 |
| East Central | Ridgeline Winds (mph) |
|---|---|
| Sunday Evening | W 5-15 |
| Sunday Night | SW 15-25 |
| Monday Morning | S 25-35 |
| Monday Afternoon | WSW 25-35 |
| East South | Ridgeline Winds (mph) |
|---|---|
| Sunday Evening | WSW 5-15 |
| Sunday Night | WSW 20-30 |
| Monday Morning | WSW 20-30 |
| Monday Afternoon | WSW 25-35 |
| Mt. Hood | Ridgeline Winds (mph) |
|---|---|
| Sunday Evening | WSW 25-35 |
| Sunday Night | WSW 30-40 |
| Monday Morning | WSW 30-40 |
| Monday Afternoon | WSW 35-50 |
Issued: 2:19 PM PST Sunday, December 20, 2020
Extended Weather Synopsis
A high pressure moving into the region from the west should help clear skies Tuesday night and temperatures should be cold throughout the region with 1000-2500 ft freezing levels. On Wednesday, the ridge axis moves over the region late in the day. Expect a mostly sunny conditions with significant warming west of the Cascade Crest while a cold pool strengthens east of the Cascade Crest. Light low-level E flow develops and ushers cold air through the mountain gaps. This low-level flow increases into the moderate range Wednesday night through Thursday with the ridge continuing to dominate our weather, but shifting east. The next system is slated to arrive on Friay.
Extended Snow Level (ft)
| Tuesday Night | Wednesday | Wednesday Night | Thursday | |
|---|---|---|---|---|
| West North | 500' | 2000' | 2000' | 4000' |
| Snoqualmie Pass | 500' | 2000' | 1500' | 1500' |
| Mt. Hood | 1000' | 2000' | 1500' | 1500' |
| West North | Elevation |
|---|---|
| Tuesday Night | 500' |
| Wednesday | 2000' |
| Wednesday Night | 2000' |
| Thursday | 4000' |
| Snoqualmie Pass | Elevation |
|---|---|
| Tuesday Night | 500' |
| Wednesday | 2000' |
| Wednesday Night | 1500' |
| Thursday | 1500' |
| Mt. Hood | Elevation |
|---|---|
| Tuesday Night | 1000' |
| Wednesday | 2000' |
| Wednesday Night | 1500' |
| Thursday | 1500' |
Jump to: Weather Forecast I Precipitation I Snow Level I 5000' Temps I Ridgeline Winds I Extended Weather
Previous forecast from Dec 20, 2020
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.