Issued: 2:14 PM PST Monday, December 27, 2021
by Robert Hahn

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

Weather Synopsis

Sunday night and Monday might have been the coldest 24-hour period in the last several years in the Pacific Northwest, but the next few days will only moderate slightly. Conditions remain dangerously cold, so bundle up! Fraser river outflow continues to bring cold air into the lowlands.

Our NNW flow pattern continues with a weak system moving parallel to our coastline in the near-shore waters. It glances our region with some light snowfall to the western parts of the Olympics Monday evening. Snow should be most impactful for Mt. Hood, where we expect 2-4" of low-density snow overnight and another 1-3" on Tuesday as the low moves south of the region. The exact storm track will determine how much snow Mt. Hood gets and whether snow reaches into the southern Washington Cascades. Most of Washington State should experience partial cloud cover and light winds. With the low off our coast, E flow will increase, sloshing the coldest air against the east slopes of the Cascades and filtering it through the mountain gaps.

Another shortwave moving southward from interior British Columbia may spawn some light snowfall for southern parts of our forecast region Tuesday night. At this time we're expecting several more inches for Mt. Hood, but it is possible this snowfall and widespread than we currently forecast.

Wednesday features fair weather with partly cloudy skies and should be very slightly warmer than Tuesday.

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 in the evening with a chance of very light snow, then partial clearing overnight.
Tuesday Mostly cloudy.
Monday Night Mostly cloudy in the evening, then partial clearing overnight.
Tuesday Mostly sunny in the morning, then mostly cloudy in the afternoon.
Monday Night Mostly cloudy in the evening, then partial clearing overnight.
Tuesday Mostly sunny in the morning, then mostly cloudy in the afternoon.
Monday Night Mostly cloudy with a slight chance of very light snow in the early morning hours.
Tuesday Partly cloudy in the morning with increasing clouds in the afternoon.
Monday Night Mostly cloudy in the evening, then partial clearing overnight. Increasing light E wind at the Pass.
Tuesday Partly cloudy in the morning with increasing clouds in the afternoon. Light E wind at the Pass.
Monday Night Mostly cloudy with a slight chance of very light snow in the early morning hours. Increasing light E wind at the Pass.
Tuesday Partly cloudy in the morning with increasing clouds in the afternoon. Light E wind at the Pass.
Monday Night Mostly cloudy in the evening, then partial clearing overnight.
Tuesday Mostly sunny in the morning, then becoming partly cloudy in the afternoon.
Monday Night Mostly cloudy in the evening, then partial clearing overnight.
Tuesday More sun than clouds in the morning, then increasing clouds in the afternoon.
Monday Night Mostly cloudy.
Tuesday Partly cloudy in the morning, then becoming mostly cloudy in the afternoon.
Monday Night Increasing light snow.
Tuesday Light snow snow showers.

Issued: 2:14 PM PST Monday, December 27, 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 0.10 0 0 0
Mt Baker Ski Area 0 0 0 0
Mt. Loop - Barlow Pass 0 0 0 0
Stevens Pass 0 0 0 0
Snoqualmie Pass 0 0 LT 0.10 0
Crystal Mt 0 0 0 0
Paradise 0 LT 0.10 LT 0.10 0
White Pass 0 0 0 0
Washington Pass 0 0 0 0
Mission Ridge 0 0 0 0
Salmon la Sac - Gallagher Head 0 0 0 0
Tieton River - Darland Mt. 0 0 0 0
Mt Hood Meadows LT 0.10 LT 0.10 LT 0.10 LT 0.10
Timberline LT 0.10 LT 0.10 LT 0.10 LT 0.10
Hurricane Ridge Precipitation (in)
Monday Night LT 0.10
Tuesday 0
Tuesday Night 0
Wednesday 0
Mt Baker Ski Area Precipitation (in)
Monday Night 0
Tuesday 0
Tuesday Night 0
Wednesday 0
Mt. Loop - Barlow Pass Precipitation (in)
Monday Night 0
Tuesday 0
Tuesday Night 0
Wednesday 0
Stevens Pass Precipitation (in)
Monday Night 0
Tuesday 0
Tuesday Night 0
Wednesday 0
Snoqualmie Pass Precipitation (in)
Monday Night 0
Tuesday 0
Tuesday Night LT 0.10
Wednesday 0
Crystal Mt Precipitation (in)
Monday Night 0
Tuesday 0
Tuesday Night 0
Wednesday 0
Paradise Precipitation (in)
Monday Night 0
Tuesday LT 0.10
Tuesday Night LT 0.10
Wednesday 0
White Pass Precipitation (in)
Monday Night 0
Tuesday 0
Tuesday Night 0
Wednesday 0
Washington Pass Precipitation (in)
Monday Night 0
Tuesday 0
Tuesday Night 0
Wednesday 0
Mission Ridge Precipitation (in)
Monday Night 0
Tuesday 0
Tuesday Night 0
Wednesday 0
Salmon la Sac - Gallagher Head Precipitation (in)
Monday Night 0
Tuesday 0
Tuesday Night 0
Wednesday 0
Tieton River - Darland Mt. Precipitation (in)
Monday Night 0
Tuesday 0
Tuesday Night 0
Wednesday 0
Mt Hood Meadows Precipitation (in)
Monday Night LT 0.10
Tuesday LT 0.10
Tuesday Night LT 0.10
Wednesday LT 0.10
Timberline Precipitation (in)
Monday Night LT 0.10
Tuesday LT 0.10
Tuesday Night LT 0.10
Wednesday LT 0.10

Issued: 2:14 PM PST Monday, December 27, 2021

Snow Level (ft)

Monday Evening Monday Night* Tuesday Morning* Tuesday Afternoon* Tuesday Evening* Tuesday Night* Wednesday Morning* Wednesday Afternoon*
Olympics 0 0 0 0 0 0 0 0
West North 0 0 0 0 0 0 0 0
West Central 0 0 0 0 0 0 0 0
West South 0 0 0 500' 0 0 0 0
Stevens Pass 0 0 0 0 0 0 0 0
Snoqualmie Pass 0 0 0 0 0 0 0 0
East North 0 0 0 0 0 0 0 0
East Central 0 0 0 0 0 0 0 0
East South 0 0 0 500' 0 0 0 0
Mt. Hood 0 0 0 0 0 0 0 0
Olympics Elevation
Monday Evening 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 0'
Tuesday Evening* 0'
Tuesday Night* 0'
Wednesday Morning* 0'
Wednesday Afternoon* 0'
West North Elevation
Monday Evening 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 0'
Tuesday Evening* 0'
Tuesday Night* 0'
Wednesday Morning* 0'
Wednesday Afternoon* 0'
West Central Elevation
Monday Evening 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 0'
Tuesday Evening* 0'
Tuesday Night* 0'
Wednesday Morning* 0'
Wednesday Afternoon* 0'
West South Elevation
Monday Evening 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 500'
Tuesday Evening* 0'
Tuesday Night* 0'
Wednesday Morning* 0'
Wednesday Afternoon* 0'
Stevens Pass Elevation
Monday Evening 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 0'
Tuesday Evening* 0'
Tuesday Night* 0'
Wednesday Morning* 0'
Wednesday Afternoon* 0'
Snoqualmie Pass Elevation
Monday Evening 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 0'
Tuesday Evening* 0'
Tuesday Night* 0'
Wednesday Morning* 0'
Wednesday Afternoon* 0'
East North Elevation
Monday Evening 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 0'
Tuesday Evening* 0'
Tuesday Night* 0'
Wednesday Morning* 0'
Wednesday Afternoon* 0'
East Central Elevation
Monday Evening 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 0'
Tuesday Evening* 0'
Tuesday Night* 0'
Wednesday Morning* 0'
Wednesday Afternoon* 0'
East South Elevation
Monday Evening 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 500'
Tuesday Evening* 0'
Tuesday Night* 0'
Wednesday Morning* 0'
Wednesday Afternoon* 0'
Mt. Hood Elevation
Monday Evening 0'
Monday Night* 0'
Tuesday Morning* 0'
Tuesday Afternoon* 0'
Tuesday Evening* 0'
Tuesday Night* 0'
Wednesday Morning* 0'
Wednesday Afternoon* 0'

Issued: 2:14 PM PST Monday, December 27, 2021

5000' Temperatures (°F)

Monday Night Tuesday
Max / Min Max / Min
Olympics 10 / 6 20 / 12
West North 9 / 4 18 / 7
West Central 10 / 5 19 / 9
West South 10 / 7 22 / 9
Stevens Pass 8 / 4 16 / 3
Snoqualmie Pass 14 / 8 17 / 6
East North 0 / -10 10 / -2
East Central 9 / 3 17 / 3
East South 10 / 5 17 / 4
Mt. Hood 12 / 8 23 / 9
Olympics 5000' Temperature Forecast
(Max / Min)
Monday Night 10 / 6
Tuesday 20 / 12
West North 5000' Temperature Forecast
(Max / Min)
Monday Night 9 / 4
Tuesday 18 / 7
West Central 5000' Temperature Forecast
(Max / Min)
Monday Night 10 / 5
Tuesday 19 / 9
West South 5000' Temperature Forecast
(Max / Min)
Monday Night 10 / 7
Tuesday 22 / 9
Stevens Pass 5000' Temperature Forecast
(Max / Min)
Monday Night 8 / 4
Tuesday 16 / 3
Snoqualmie Pass 5000' Temperature Forecast
(Max / Min)
Monday Night 14 / 8
Tuesday 17 / 6
East North 5000' Temperature Forecast
(Max / Min)
Monday Night 0 / -10
Tuesday 10 / -2
East Central 5000' Temperature Forecast
(Max / Min)
Monday Night 9 / 3
Tuesday 17 / 3
East South 5000' Temperature Forecast
(Max / Min)
Monday Night 10 / 5
Tuesday 17 / 4
Mt. Hood 5000' Temperature Forecast
(Max / Min)
Monday Night 12 / 8
Tuesday 23 / 9

Issued: 2:14 PM PST Monday, December 27, 2021

Ridgeline Winds (mph)

Monday Evening Monday Night Tuesday Morning Tuesday Afternoon
Olympics WSW 5-15 W 0-10 NW 0-10 NW 0-10
West North W 0-10 W 0-10 WNW 0-10 NNW 0-10
West Central WNW 5-15 NW 5-15 WNW 5-15 WNW 0-10
West South W 0-10 WNW 0-10 NW 0-10 WNW 0-10
Stevens Pass W 5-15 WNW 5-15 W 0-10 W 5-15
Snoqualmie Pass WNW 5-15 NW 5-15 WNW 5-15 WNW 5-15
East North WNW 5-15 WNW 5-15 WNW 5-15 WNW 5-15
East Central WNW 10-20 WNW 10-20 WNW 10-20 WNW 5-15
East South WNW 5-15 NW 5-15 WNW 0-10 WNW 0-10
Mt. Hood W 15-25 W 10-20 W 5-15 W 5-15
Olympics Ridgeline Winds (mph)
Monday Evening WSW 5-15
Monday Night W 0-10
Tuesday Morning NW 0-10
Tuesday Afternoon NW 0-10
West North Ridgeline Winds (mph)
Monday Evening W 0-10
Monday Night W 0-10
Tuesday Morning WNW 0-10
Tuesday Afternoon NNW 0-10
West Central Ridgeline Winds (mph)
Monday Evening WNW 5-15
Monday Night NW 5-15
Tuesday Morning WNW 5-15
Tuesday Afternoon WNW 0-10
West South Ridgeline Winds (mph)
Monday Evening W 0-10
Monday Night WNW 0-10
Tuesday Morning NW 0-10
Tuesday Afternoon WNW 0-10
Stevens Pass Ridgeline Winds (mph)
Monday Evening W 5-15
Monday Night WNW 5-15
Tuesday Morning W 0-10
Tuesday Afternoon W 5-15
Snoqualmie Pass Ridgeline Winds (mph)
Monday Evening WNW 5-15
Monday Night NW 5-15
Tuesday Morning WNW 5-15
Tuesday Afternoon WNW 5-15
East North Ridgeline Winds (mph)
Monday Evening WNW 5-15
Monday Night WNW 5-15
Tuesday Morning WNW 5-15
Tuesday Afternoon WNW 5-15
East Central Ridgeline Winds (mph)
Monday Evening WNW 10-20
Monday Night WNW 10-20
Tuesday Morning WNW 10-20
Tuesday Afternoon WNW 5-15
East South Ridgeline Winds (mph)
Monday Evening WNW 5-15
Monday Night NW 5-15
Tuesday Morning WNW 0-10
Tuesday Afternoon WNW 0-10
Mt. Hood Ridgeline Winds (mph)
Monday Evening W 15-25
Monday Night W 10-20
Tuesday Morning W 5-15
Tuesday Afternoon W 5-15

Issued: 2:14 PM PST Monday, December 27, 2021

Extended Weather Synopsis

The December pattern of storm systems dropping down the coast toward our region from the Gulf of Alaska continues - and so does the cold temperatures. The first significant storm to impact our region approaches Wednesday evening. Although the upper-level support with this system may be over central BC, it should spawn a low right along the coast that picks up sufficient moisture to bring a healthy round of snowfall. The moisture arrives from NW to SE in the early morning hours on Thursday. SW winds and snowfall should peak in the moderate range Thursday morning. This system does bring significant warming at cloud level relative to the temperatures we've experienced. Thus, the mountain snow should be low-density, but not quite as fluffy as in recent storms. With cold temperatures in place, we expect snow down to sea level to start the storm, but we might get a mix with rain or freezing rain in the lowlands. Winds shift northerly behind the trough, cutting off post-frontal snow showers from north to south Thursday night and allowing Fraser outflow to intensify once again, bringing more cold air to the lowlands. We expect fair weather and cold temperatures in most areas on Friday.

Extended Snow Level (ft)

Wednesday Night* Thursday * Thursday Night* Friday
West North 0 0 0 0
Snoqualmie Pass 0 0 0 0
Mt. Hood 0 500' 500' 0
West North Elevation
Wednesday Night* 0'
Thursday * 0'
Thursday Night* 0'
Friday 0'
Snoqualmie Pass Elevation
Wednesday Night* 0'
Thursday * 0'
Thursday Night* 0'
Friday 0'
Mt. Hood Elevation
Wednesday Night* 0'
Thursday * 500'
Thursday Night* 500'
Friday 0'

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

Previous forecast from Dec 27, 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’.