Green’s Dictionary of Slang

lady snow n.2

[SE lady + snow n.1 (2a); note cocaine is a ‘feminine’ drug, see girl n.2 ]

(drugs) cocaine.

[US]P. Thomas Down These Mean Streets (1970) 258: That’s my woman, Lady Snow. [...] I sure wish I could cop some.
[US]R.R. Lingeman Drugs from A to Z (1970).