Blizzard = homozygous for charcoal + homozygous for amel.
So as I understand it, you can't directly make blizzards by breeding a charcoal to anything unless the charcoal is het for amel. Then you could breed with another of the same genotype & get 1/4 blizzards. Best route I can see is charcoal x amel = gives you nothing but normals het for charcoal & amel. Breed 2 normals from that clutch & if they produce 9 normals with various hets, 3 charcoals with hets, 3 amels with hets & 1 blizzard.