Twin One

Avalanche conditions

• Slab avalanches today or yesterday.
• 30cm + of new snow, or significant drifting, or rain in the last 48 hours.
• Whumpfing or drum-like sounds or shooting cracks.
• Rapid temperature rise to near or above 0°C or wet surface snow.

Small surface hoar formed at treeline and alpine elevations in clear, calm conditions on the 27th. Breakable sun crust formed on south aspects. North aspects retained low density snow and skiing was fantastic through the 28th with no signs of instability in alpine, treeline, or below treeline. Storm brought extreme winds and warm temps on evening of 28th through 29th resulting in "upside down" dense snow overlaying low density. Storm slabs were touchy on south aspects where they overlaid sun crust. We observed recent debris of 2 Na's size 1-2 and ski cut small size 1's as we travelled. Winds were extreme in the alpine with significant scouring on windward aspects and transport well downslope on lee aspects. Wind slabs were not triggered in alpine where we travelled but we didn't go looking for them and were busy travelling through rather than lingering! Freezing level was ~1500m at 2pm on 29th, with a crust up to 1800 in places, indicating it was higher earlier.