PNWS

*γarpill- - storm cloud (Kogan 2015:237)

The origin is uncertain, but an ultimate relationship with with Akk. erpetu ‘cloud’, Ugr. ˁrpt is not to be ruled out

Ugaritic
γrpl - cloud, large storm cloud (DUL 326)
Hebrew
ˁărāpäl - thick darkness (HALOT 888)
Syriac
ˁarpellā - cloud, dark mist (LSyr. 549, SL 1141)