RobH_en_tn/isa/17/13.md

before the wind like chaff on the mountains ... like weeds whirling before a storm

These two phrases mean the same thing. The enemy armies seem powerful but God will easily stop them and send them away. Alternate translation: "like chaff on the mountains that the wind blows away ... like weeds that whirl and blow away as a storm approaches" (See: rc://en/ta/man/translate/figs-parallelism and rc://en/ta/man/translate/figs-simile)