PC

*gašm- - rain (Kogan 2015: 291)

+ Eg.-syll. gas-mu ‘storm’ (Hoch 1994:354), not universally accepted, cf. Rainey 1998:450, Woodhouse 2003:281

Ugaritic
gšm - rain, downpour (DUL 310)
Hebrew
gäšäm - rain (HALOT 205)