Preservation of snow
Unique weather and snow treatment
Mild and rainy
Many ski clubs and venues have experienced uniquely mild and rainy periods leading up to or during the winter that destroyed the snow cover, even man-made snow. This is especially frustrating when big events are planned.
Without making any guarantee, the following “snow treatment” methods have successfully preserved snow on Cross-Country competition courses during “impossibly mild” weather conditions, especially if all are used together (methods designed and implemented by Geir Olsen):
- Method 1: Cover the snow with geotextile cloth; the cloth will protect against further melting
- Method 2: If geotextile fabric is not used, spray (a lot of) water on the snow and then salt. Water and salt with “freeze” the snow and preserve it before more mild weather approaches. Nozzles can be removed from lances (if available) and used for watering.
- Method 3: Use efficient and modern snow guns, and install a Snomax pump such that snow can be made on -1.7 degrees C wetbulb temperature.
Over time, with no precipitation and with low humidity, heavy use (many skiers) and frequent grooming may cause very soft and “loose” snow, often called “sugar snow”. This is seen more often in venues with mostly man-made snow. The ice/snow crystals are rounded, and it is imposible to even create a snowball. It is very difficult to fix this problem, but the following three solutions may work:
- Add (lots of) water, groom, then salt the snow
- Scrape away the sugar snow (manually with showels or mechanically with the front blade) such that a deeper and more humid layer of snow is exposed. This will harden better after grooming. NOTE: Before attempting this, check with a drill and auger if the deeper snow layer has more humid snow.
- Add new snow with a higher water content and/or better crystal structure (ice scraped off indoor ice rinks may be used). Then mix, groom and salt the snow.
If sugar snow is a frequent and annual problem, the venue operator should consider reducing the frequency of grooming with large machines, or only groom in the evenings such that the snow can always harden for many hours during the night. For Cross-Country and Biathlon venues, a snowmobile pulling the appropriate attachment should be used instead of the larger machines some days. This will reduce the destruction of the snow crystals.
Indoor ski arenas
Indoor ski arenas have a stable and controlled “weather”, but will often see challenges with the snow quality (perhaps due to the high humidity) where the snow after a while becomes “tired” and similar to sugar snow.
The solution for indoor arenas is to renew the snow in some way, similar to the methods suggested for outdoor venues.
- by adding and mixing in new snow with higher water content and sharper crystals
- by watering and salting the snow (although this is usually a short.term solution)
- by installing special made snowguns (for example in the roof structure) that the create snow daily without increasing the local humidity. This requires an air temprature of at least -2 degree Celsius.
At certain alpine resorts, snow fence is used to catch and harvest natural snow, which is later groomed.
These fences effectively protect snow from alpine gusts that would otherwise blow it off the peak — at least until snow cats can pack the powder down and pave the trail. The fences are then transplanted to another area, and the process repeats itself.
If the alpine terrain lies above the tree line, this technique may be applicable on a large scale. When used, the process begins in early September, long before any snow dusts the peaks. Pieces of 1.8-meter steel are pounded into the ground, which later freeze into place so that fencing can be tied around it securely.
Sunshine Village on the Continental divide in Canada is probably the ski resort in the World that does most snow farming through this snow fence technique. Sunshine Village’s low-energy “snow farming” technique uses several thousand pieces of steel and roughly 20 kilometres of plastic fencing to trap snowfall on its upper peaks, reducing the need for traditional snow-making.