Avalanche Forecast Jasper National Park

Monday 28th January 2019

Avalanche Danger Ratings Mon 28th Jan 4:43PM Danger Ratings Alpine: Moderate Danger Ratings Treeline: Moderate Danger Ratings Below Treeline: Low Wind Slabs Wind Slabs Deep Persistent Slabs Deep Persistent Slabs

Parks Canada Forecaster: jasper snow safety

Date Issued:

Valid Until:

A modest recent snowfall with wind was enough to cause notable new avalanches. Avoid obvious windslabs on steep slopes, and critically assess the the terrain you enter - if you trigger a Deep Persistent slab, what will the consequences be?

Weather Forecast

Tuesday will be clear, Treeline Low -10, Hi -5, with Light NW winds. An inversion is possible, with cold air pooling in valley bottoms.Wednesday-Thursday: temperatures slowly rise, with sporadic cloud cover, and light snowfall possible. Light W winds may rise to Moderate.A detailed mountain weather forecast is available from Avalanche Canada.

Snowpack Summary

5-10cm of snowfall on Sunday with SW - NW winds created wind slabs in lee and cross-loaded terrain. Surfaces became moist on solar slopes at treeline Monday. A layer of weak surface hoar is now buried 10-20cm deep. Below, a strong mid-pack sits over depth-hoar in the lower third of the snowpack (giving sudden results in snowpack testing Saturday).

Avalanche Summary

A natural Size 3 Deep Persistent slab was observed Monday on a steep (35+ degrees) Alpine South-West facing slope. Triggered by a smaller windslab, it stepped down to depth hoar and the ground. Several windslabs to Size 2 were also observed (Alpine S and E aspects). Help forecast - share observations HERE, on the Mountain Information Network!

Confidence

Due to the number of field observations on Monday

Wind Slabs Wind Slabs

Likelihood

Possible

Expected Size

1 - 2

New snow on Sunday arrived with Strong winds (ranging from SW to N) creating windslabs over a variety of surfaces, including suncrust, surface hoar, and wind pressed areas. While natural activity has tapered, human triggering remains possible.

Use caution in lee and cross-loaded areas. Recent wind loading has created new wind slabs.Watch for surface cracking and stiffer surface layers of snow. Avoid wind loaded terrain.

Aspects: North, North East, East, South East, South, South West.

Elevations: Alpine, Treeline.

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Deep Persistent Slabs Deep Persistent Slabs

Likelihood

Possible - Unlikely

Expected Size

1.5 - 3.5

A natural avalanche Monday on this layer shows that only minor changes may wake this generally dormant dragon. Triggering is most likely in thin areas, with variable snowpack depth. Use terrain choice and safe practices to minimize consequences.

Avoid thin, rocky or unsupported slopes.Ride slopes one at a time and spot for your partners from safe locations.

Aspects: All aspects.

Elevations: Alpine, Treeline.

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