The new wave of the epidemic is coming on with menacing force.
Tips
usage
Describes threats bearing down: storms, epidemics, enemies, competitors, criticism. Always negative — the thing described is dangerous or unwelcome. Natural in news and commentary.
memory
来 (coming) + 势 (momentum) + 汹汹 (roaring, surging — same 汹 as in 波涛汹涌 'raging waves'). Picture a tsunami roaring in: that's 来势汹汹.