Proto-MSA

*lsy - rain (Kogan 2011: 194)

Mehri

əwsū(t), məwsē - rain (ML 256)

Soqotri

ľíso - (3 sg. f.) to rain (LS 234; CSOL I 604; CSOL II 529; Naumkin et al. 2015a:78)

This is an impersonal verb used in 3 sg. f. only (sometimes with mέsɛ as direct object)