Does USSR want to fly defending ground support with Pe-2 (snow and forest = factor 1)? And does USSR want to use winterized units in defense?
Here are final odds if Allies answer "yes" to every question.
Is assault chosen in every combat?
Edit: I might have miscalculated attack odds in Finland, but who cares when things are not going well anyway. Sons of north, ATTACK!

If your attack is going really well, it's an ambush.
-Murphy's war law