Green’s Dictionary of Slang

snowed adj.

also snowbound
[snow n.1 (2)]

(drugs) under the influence of heroin or cocaine; thus punning synon. snowed in, snowed up.

[US]R. McAlmon Miss Knight (1963) 55: ‘I’m snowbound now, Mary,’ she confided to inform the others that she had just sniffed cocaine.
[US]R.S. Gold ‘Miscellaneous Notes’ in AS III:2 167: Snowed In: Dopey, as if full of cocaine (Snow).
[US]R. Chandler ‘Guns At Cyrano’s’ in Red Wind (1946) 199: He was snowed to the hairline. [Ibid.] 200: That snowed-up hoodlum looked like a life-taker to me.
[US]Monteleone Criminal Sl. (rev. edn).
[US]H. Gold Man Who Was Not With It (1965) 222: I figured on how to get snowed.
[US]P. Crump Burn, Killer, Burn! 323: I got snowed to the gills.
[US]St Louis Post-Dispatch (MO) 1 Sept. 55/1: [headline] Why Are We Still Snowed On Cocaine?