Avalanche Forecast

Issued: Jan 23rd, 2020 10:00AM

The alpine rating is below threshold, the treeline rating is below threshold, and the below treeline rating is below threshold.

Northwest Avalanche Center NWAC, Northwest Avalanche Center

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The avalanche danger will decrease on Friday. Fresh and shallow wind slabs may be found on lee slopes at upper elevations. You can still trigger a loose wet avalanche on very steep slopes at lower elevations where wet surface snow exists.  

Summary

Discussion

The east south zone did not see the huge precipitation amounts that fell further north and west in the Washington Cascades. However warm air flooded the region Wednesday night and Thursday with temperatures pushing well above freezing at area Snotels. With showers decreasing tonight and cooler air moving in aloft, the surface snow should begin to refreeze at mid and upper elevations later tonight through Friday afternoon. 

Winds at ridgetop levels will be strong enough to transport new snow and form fresh shallow wind slabs on lee slopes. Check the bond of the new snow to the refreezing wet snow underneath and be cautious around steep slopes with freshly wind-drifted snow. 

The snow surface will remain moist or wet at lower elevations where snow levels are slow to cool. Natural loose wet avalanches are no longer likely, but you can still trigger a  loose wet avalanche on very steep slopes. If you find wet unconsolidated surface snow, avoid slopes steeper than 35 degrees, especially near cliffs, creeks and other terrain traps. Remember that loose wet avalanches are often surprisingly powerful and being caught in even a small one can be dangerous.

Choosing lower angled slopes (less than 35 degrees)  is the best way to avoid an avalanche, like this wet loose slide near Timberline Lodge, Mt Hood. Photo: Geoff Lodge 1-18-20

Forecast Schedule and No Rating definition

We do not have enough specific snowpack information to issue an avalanche hazard rating for the East South zone. However, even when No Rating is applied, applicable avalanche conditions and backcountry travel advice will be provided throughout the season - this forecast is updated every day, all winter long!  When weather systems produce very dangerous avalanche conditions in adjacent zones, NWAC will issue an avalanche warning for this zone as well.

Snowpack Discussion

January 23rd, 2020 (The regional synopsis is updated every Thursday @ 6 pm)

January to Remember

A parade of storms since the New Year began brought relentless precipitation, and impressive snowpack growth throughout the region. Areas along the west slopes of the Cascades have rarely gone more than 24-48hrs without precipitation. In the past three weeks, the Volcanoes and Passes received 20-28in of water equivalent, translating into incredible snowfall totals - Mt. Baker Ski Area reported 240in of new snow since January 1. The majority of NWAC weather station sites are reporting snow depths well over 120% of normal for this time of year. Ongoing precipitation and fluctuating snow levels have maintained elevated avalanche danger throughout the month, with avalanche warnings issued for nearly all forecast zones on 4 separate days (January 6, 7, 12, 23).  

Snow depth imagery for the Northwest Region on January 23, 2020. Many areas in the Cascades and Olympics show well over 100 inches of snow on the ground. Image courtesy of NOHRSC Regional Snow Analysis

Location

January 1-23 Precipitation (Water Equivalent)

Hurricane Ridge

14.79”

Mt Baker Ski Area

28.65”

Harts Pass

11.2”

Stevens Pass

20.26”

Leavenworth

4.01”

Snoqualmie Pass

25.43”

Paradise, Mt Rainier

24.13”

Mt Hood Meadows

22.34”

Table 1: Precipitation totals for select weather stations January 1-23, 2020. Huge numbers at Baker, Rainier, Hood, and the Passes and there is still another week left this month.

MLK Weekend and a Pattern of Rain on Dry Snow

After a prolonged cold period with arctic air and lowland snow, MLK weekend brought unseasonably warm temperatures and a rapid thaw. High snow levels and rain caused wet avalanche activity throughout the region January 18-19. A few very large natural avalanches occurred at upper elevations where all precipitation fell as snow. A cooling trend followed, creating a pronounced crust that is now buried in almost all forecast zones. Cold, dry snow January 21-22 was followed by a rapid warm-up and the most significant rain on snow event yet, causing avalanche warnings on January 23 for 5 of our 10 forecast zones.

The crown of a very large avalanche around 10,000ft on the Newton Headwall of Mt Hood which likely occurred during the storm late last week. 01/19/20 Photo: Kevin Kayl

The buried MLK crust is widespread throughout the region and a prominent marker in the snowpack. Crystal Backcountry 01/20/20 Photo Jeremy Allyn

One More Week To Go

January isn’t over yet, and the long term forecast continues to show an active and wet weather pattern for the Northwest. The low-snow, drought-like conditions of the early season seem like a distant memory at this point. We’ve certainly made up for lost time in 2020, and this already impressive month looks to end with a bang.

Valid until: Jan 24th, 2020 10:00AM