SOME KEY SPRING TIME CONSIDERATIONS:
- Recent Avalanche activity
- Recent Precipitation and/ or wind
- Intense solar activity / First Sun
- Warm, above freezing temperatures on consecutive non-freezing nights or Rain
- Cornice failure
Spring is a wonderful time for ski touring. Warm weather and sunny skies after fast moving storms can be a recipe for a great time. The challenge is to not forget about avalanches as you’re out skiing in the sunshine.
On a recent bluebird day touring in Norway we observed numerous examples of the types of hazards that can be seen or develop on a single day tour. Here’s a little picture review . . .
#1 DON’T FORGET ABOUT EXISTING PROBLEMS
#2 EVEN THOUGH IT IS SUNNY DON’T FORGET ABOUT THE NEW SNOW
#3 RECENT WINDLOADING
#4 SOLAR ACTIVITY
Springtime often brings melt-freeze cycles. During the day, the air temperatures rise to above freezing and the snowpack melts. At night, the temperatures drop below freezing and the snowpack freezes. This cycle of daytime melting and night time freezing can go on for days or even weeks.
Things to think about during a melt-freeze cycle:
Did it freeze last night? If yes, how long did the temperature stay below freezing?
This can offer a sense of how thick the freeze is. Knowing how thick the freeze might be is important, as conditions can change rapidly in the springtime. If it froze for only an hour, the window for safe travel is going to be shorter than if temperatures were below freezing for 10 hours. In other words a good thick freeze buys you more time for that snow to be in the sun before it can weaken.
If there was no freeze overnight, be careful. The snowpack did not regain strength, but continued to lose strength overnight. Often, significant avalanche activity occurs after the 2nd or 3rd consecutive non-freezing night.
In the spring, strong solar radiation and/or warm temperatures can weaken the snow in a matter of minutes. Avalanche danger can change from LOW to HIGH very quickly. Be alert to changing conditions and be prepared to adjust your travel plans accordingly.
By the time we finished our day we saw at least 10-20 new avalanches triggered by the new strong spring sun.