South Rockies

The likelihood of human triggering large avalanches on deeply buried weak layers is keeping the hazard at HIGH on Friday. Travel in avalanche terrain is NOT recommended.

High -

THURSDAY NIGHT: Clear skies / Light, southeasterly winds / Alpine low 6 C / Freezing level 3100 m.FRIDAY: Sunny / Light, westerly winds / Alpine high 6 C / Freezing level 2900 m.SATURDAY: Mostly cloudy / Light, northeasterly winds / Alpine high 0 C / Freezing level 2400 m.SUNDAY: Snow/rain; 5-10 mm.  / Light, easterly winds / Alpine high -3 C / Freezing level 1700 m.

On Wednesday, an explosive control mission produced an avalanche with every shot placed (nearly 20 in total). They were loose wet avalanches on sun-exposed slopes and dry, slab avalanches on northerly aspects, up to size 2.5. Additionally, large (size 2-2.5) loose wet natural avalanches continue to occur on solar aspects.A report from our South Rockies Field Team on Tuesday in the Elk Valley described numerous natural persistent slab releases reaching size 2 (large) on southeast aspects at around 2200 metres. Further to this activity, any sun-exposed snow became isothermal (slushy and cohesionless), and huge whumpfs that collapsed the basal snowpack were triggered during ski touring. Check out their video HERE.Given the above activity, loose wet avalanches remain a daily concern in steep, sun-exposed terrain (and in runout zones) while concern is increasing for deep basal (bottom of the snowpack) weaknesses that have the potential to produce very large and destructive slab avalanches.

Upper snowpack: Getting warm and moist during the day, likely forming weak crusts overnight that deteriorate during the day. On sunny aspects the upper snowpack has become increasingly isothermal (slushy and cohesionless) with successive days of warming. Mid pack: The mid-snowpack consists of facets (weak, sugary snow) and layers of harder wind effected snow. Recent loose wet avalanches have been entraining additional mass by gouging into this faceted snow. These facets have also acted as a failure plane in recent slab releases.Lower pack: The strength of the lower snowpack is increasingly in question in shallower areas where the February cold was able to weaken basal (bottom of the snowpack) layers and warm temperatures are increasing the strain on these weaknesses each day.  Many of the recent slab avalanches failed on these facets sitting just above the ground. It's a good time to stand aside and let the mountains shed their coat. Stability will improve greatly when temperatures cool off.