Avalanche Forecast

Issued: Mar 28th, 2019 4:40PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Loose Wet and Wind Slabs.

cgarritty, Avalanche Canada

Purcells.

Get in, get after it, and get out. Conditions are approaching ideal for tackling bigger objectives, as long as you're savvy about exiting avalanche terrain before the heat of the day.

Summary

Confidence

High -

Weather Forecast

Thursday night: Clear. Light northeast winds.Friday: Mainly sunny with a mix of cloud in the south of the region. Light variable winds. Alpine high temperatures around -2 with freezing levels to 2000 metres.Saturday: A mix of sun and cloud with cloud increasing over the day. Light northwest winds shifting southwest. Alpine high temperatures around 0 with freezing levels to 2100 metres.Sunday: Mainly cloudy with isolated flurries bringing a trace of new snow. Light southwest winds. Alpine high temperatures around -1 with freezing levels to 2000 metres.Overnight freezing levels will remain elevated during this period, dropping briefly each night to between 1000 to 1500 metres.

Avalanche Summary

No new avalanches were reported in the Purcells over the past couple of days, but reports from neighbouring regions have shown the snow from Tuesday's storm reacting to skier traffic, ski cutting, and explosives control with 10-25 cm-deep slabs propagating easily over previous surface crusts. All aspects were represented in reports, with thicker wind-loaded slabs more prominent on north to east aspects and wet slabs observed on sun-exposed south to west aspects. Similar conditions were likely to exist in areas of the Purcells that received more than a skiff of new snow from Tuesday's storm. Looking forward, expect continuing warm, sunny weather to ramp up loose wet avalanche problems with each day's warming cycle.

Snowpack Summary

Variable new snow amounts of about 5 to 25 cm from a storm earlier in the week buried a surface of melt-freeze crust in most areas above 1500 metres. Below this elevation it buried variably moist or crusty surfaces. Precipitation fell as rain below about 1100 metres.The snowpack below about 1500 metres has been disappearing rapidly under the influence of sustained above freezing temperatures, strong sunshine, and rain. The chance of loose wet avalanches increases each day as these factors break down surface crusts and bring snow to its melting point.The mid snowpack is generally consolidated and strong, but exceptions may exist on north aspects above 2000 m, where a gradually strengthening layer of faceted grains buried 40 to 60 cm deep may still be preserved below an overlying slab of old and hard wind-affected snow.The base of the snowpack is composed of weak faceted snow which may coexist with a melt-freeze crust. Only one very large persistent slab was reported to have failed at this layer during last week's warming event.

Problems

Loose Wet

A springtime regime of daily warm temperatures and sunshine will tend to destabilize surface snow each day, especially on steep, sunny slopes. Larger avalanches become possible during peak warming.

Avoid exposure to terrain traps, where the consequences of a small avalanche could be serious.Start and finish early to reduce your exposure to avalanche terrain during the heat of the day.This problem may affect shaded aspects where air temperatures exceed 0 degrees.

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Wind Slabs

Lingering slabs from Tuesday's storm may remain reactive to human triggers on Friday. This problem is likely to become increasingly confined to steeper, wind loaded slopes at ridgecrest. Sun-exposed aspects may produce wet slabs during peak warming.

Be careful around wind loaded pockets near ridge crests and roll-overs.Use ridges or ribs to avoid pockets of wind loaded snow.Wind slab danger varies over the region. Increase caution in areas with 15 or more cm of recent snow

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 1.5

Valid until: Mar 29th, 2019 2:00PM