Hi HazelNuts39,
Assume snow requires 4.18 J/(g•K); & Latent heat of fusion of ice is 333.55 J/g
Then 1.66gm ice at -40 would require 4.18*1.66*40 = 277 J to be raised to 0C as ice.
Plus 1.66*333.55 J to melt at 0C = 554 J.
Total = 831 J.
If that amount of snow could accumulate in 20secs, then in 1 hour you would need 149,580 J or extra power source of about .04 KWh.
It doesn't sound much - but I can't spot the error.