KE should decrease
Step-by-step explanation:
The momentum, p(t)=m(t)⋅v(t), of the snowball should remain constant as there is no external force acting on the system, that is the snowball and the snowflakes it gathers, in the direction of travel.
i.e. ΣF=.p=0 so p=const.
As for KE, T(t)=12mv2=p22m=const.m
as mass is increasing, KE should decrease
this has greatly simplified it all, as it looks at it as a point mass