这应该是一个typo（打印或排版错误）。这是两个并列的形容词最高级修饰复数名词storms，其实就是一个“one of+最高级+复数名词”的短语。如：

Skipping is one of the most enjoyable aerobic activities. 跳绳是最有乐趣的有氧健身运动之一。

"Robinson Crusoe" is one of the most famous books in the world. 《鲁宾逊漂流记》是一本世界名著。

Seacliff House is one of the most romantic ruins in Scotland. 海崖城堡是苏格兰最富有浪漫色彩的遗迹之一。