Green’s Dictionary of Slang

snowstorm n.

also snowfall
[snow n.1 (2)]

[1950s] (US drugs) the using of cocaine or morphine.

In phrases

caught in a snowstorm (adj.)

1. [1920s–50s] (US drugs) under the influence of cocaine, esp. when experiencing extreme effects.

2. [1930s] experiencing the hallucinations which accompany an overdose of morphine.