The freezing of the lakes has been slowed down this winter by an insulating layer of snow on top of the ice.
The thickness and condition of lake ice in central Finland now varies greatly.
For example, the ice thickness in Kuuhankavesi in Hankasalmi last week was 26 centimetres and in Pääjärvi in Karstula it was only 13 centimetres.
– Snow on the ice acts as an insulator and blocks frost from entering the ice. A layer of snow also pushes thin ice below the water surface and water rises to the surface,” Kemppi explains.
According to the water inspector, so-called hard ice has become more common in recent years. Hard ice is created when snow mixes with the water on the surface of the ice layer and it freezes.
Hard ice does not hold up as well as steel ice.
– The durability of hard ice is half of the durability of steel ice. Five centimeters of steel ice can carry a person, so there should be 10 centimeters of hard ice, says Kemppi.
According to Kemp, it is still impossible to predict when it is safe to go out on the ice. Central Finland’s Ely center has compiled a map of the areas of weak ice observed in Jyvässeud.
– The information has been collected from the observations of experienced ice walkers and entered into the Jäävilkku application to help outdoor enthusiasts, Kemppi states.
It’s a good idea to have proper equipment for an ice trip
Sorvari says that he has fallen on the ice many times and says that the most important piece of equipment for moving on ice is the crampons hanging around the neck.
– If you fall on the ice, you can pull yourself up with the helpers, says Sorvari.
A flotation device also provides safety on the ice. According to Sorvar, you should make the trip together with someone else.
– You should also put a rope in the backpack so that you can use it to lift someone from the ice.
You should also reserve matches and dry clothes in the plastic bag to stay warm.
It is reported from the central Finland rescue service that the weak ice has not employed the rescue service much in recent weeks.
No people have drowned in the ice, but in December, at least in the northern parts of Central Finland, some moose and deer have had to rely on water.