Spring and Summer Hazard Summary
This page was originally prepared for Avalanche-Center.org (formerly csac.org) a long time ago. It was then posted on mountain-guiding.com, where a copy still resides although that site is no longer active or maintained. Since that site is inactive this page has once again moved here.
Temperature and radiation balance are important factors in spring and summer. The snow commonly refreezes overnight and softens throughout the day. If overnight refreezing does not occur or is minimal the hazard of wet slides will increase earlier in the day.
Indications that wet slides are a potential hazard include penetrating deeper than the ankles and/or sunballs which grow into wheels, penetrating deeply into the snow.
Northerly aspects may take longer to stabilize and reach summer stability than aspects which get more solar radiation. This is especially true at higher elevations.
While summer snow (firn) is typically very stable, fresh snow may fall any time of year at higher elevations. Some winter-like stability considerations may then apply, but remember that strong solar radiation can cause especially rapid changes in the snow after such a storm. Stabilization is often quicker than in winter, but until it occurs the time of day will be an important factor to consider in route selection and timing.
Watch rock outcroppings and cliffs where the heat from the sun will be conducted into and/or under the snow.
Consider the consequences of even a small slide. In many cases even a small wet point release can carry a climber into a crevasse or over a cliff band. Beware of snowfields above any cliff bands or gullies which may threaten you from above.
Carry beacons and rescue gear, even in late spring and summer. A shovel has many uses, and if you own a beacon it doesn't make sense not to wear it in potential avalanche terrain.
Ice avalanches (icefalls) on glaciers are unpredictable. They are primarily due to glacial motion. They may be more active during or following an extended warm spell. Time of day is largely irrelevant. Minimize exposure to this hazard by traveling quickly or staying out of the runout area below these (usually) obvious areas.
