perfect storm
A chance or rare combination of individual elements, circumstances, or events that together form a disastrous, catastrophic, or extremely unpleasant problem or difficulty. The incumbent mayor's re-election campaign is getting underway amidst a perfect storm of allegations and news stories about corruption, tax evasion, and racketeering within the city's government. The oil crisis has set off a perfect storm in the Middle East, where foreign leaders have depended on its economic stability to keep their warring countries from absolute chaos and anarchy.