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In the mountains

Ongoing observations on the hill should be used to confirm, and refine or adjust, your initial hazard evaluation. Avalanches occurring or signs of recent activity are the most significant indicators of an avalanche danger and should not be ignored. On the approach observe the nature of the snow on the ground and in the air. The behaviour of snow underfoot can be very informative. Cracking and breaking away of snow blocks from beneath your feet is an indication of slab and instability. Look for signs of recent windslab deposition. Spindrift is usually a danger sign, as even fairly light winds can redistribute huge amounts of snow, packing it in as windslab on lee slopes and in other sheltered locations. Even a light surface drift can produce localised danger, especially in the tops of gullies.

Signs of a rise in temperature – such as rain, wet snow, sun balls rolling down the slope, strong sunlight, and melting snow and ice – can all be danger signs, especially if large cornices exist. If the thaw is due to strong sunshine, then different slope aspects may make a large difference, with perhaps danger on south faces but safer northerly aspects. In these circumstances, slopes of a similar aspect and altitude should be considered extremely suspect.