Perfect Storm
Multiple bad factors converging at once — the explanation of choice for disasters, since it distributes blame to the weather. Some storms are genuinely perfect; most had forecasts nobody read.
Heard in the wild
“Supply delays, flu season, and the ERP cutover — a perfect storm.”
Tone check: Cliché
Check whether each factor was foreseeable. 'Perfect storm' often translates to 'three ignored warnings, simultaneous.'