Jasper National Park Avalanche Forecast
May 5th, 2019 4:27PM
As Spring finally re-asserts itself, expect to see increasing activity with daytime warming. Meanwhile, incremental loading by small snowfalls has maintained winter-like avalanche problems on shaded slopes.
Mon-Weds: Mixed sun & cloud, light winds, no significant precip, gradually rising freezing level. Initially cool overnight temps become warm by midweek.
Mon: Scattered cloud, Freezing levels 2500m, treeline low -4, High +3
Tues: Cloud & flurries developing. Freezing level 2600m, treeline low -1.5, high +5
Wed: Treeline Low -0.5, freezing level 2700m.
Regular small, warm snowfalls have sustained Windslab and loose snow avalanche problems. This recent snow is settling rapidly, but overlies crusts and facets in the upper snowpack. The crusts are thick/strong on solar aspects. Occasional whumpfing at upper treeline & alpine. The snowpack remains faceted on shady aspects, and weak in shallow areas.
On Sunday, a large natural slab avalanche was observed at 2400m on a NE aspect. This was on Pyramid mountain near Jasper, and was most likely a recent Wind Slab (size 2.5). Numerous small (size 1), natural loose dry avalanches were also observed on steep shaded alpine terrain near Marmot Basin.
Wind slabs are more prevalent in the Marmot/Maligne areas than the icefields, as they received more recent snowfall and wind.
- Use caution in lee areas. Recent wind loading has created wind slabs.
- Test slopes before committing to them.
Aspects:North, North East, East, South East.
Weak mid-pack facets, in isolated pockets on shaded, wind-sheltered alpine slopes. May also exist on shaded upper treeline features; and on solar aspects there is a (smaller) possibility of these failing on facets over a buried crust down 15-40cm.
- Minimize exposure to terrain traps where the consequences of an avalanche could be serious.
- Carefully evaluate big terrain features by digging and testing on adjacent, safe slopes.
Springs' increasing influence is encouraging the upper snowpack to shed recent snowfall, in loose snow avalanches. Snowballing or sticky snow are indicators of this problem.
- Minimize exposure to steep slopes on warm or sunny days.
- Daytime warming will weaken surface layers, plan your day around being back to the trailhead early.
Valid until: May 6th, 2019 4:27PM