哪知

原本清晨出门时还是一片万里无云的大晴天，哪知道午后天色突变，电闪雷鸣间降下了倾盆特大暴雨。

yuán běn qīng chén chū mén shí hái shì yī piàn wàn lǐ wú yún de dà qíng tiān, nǎ zhī dào wǔ hòu tiān sè tū biàn, diàn shǎn léi míng jiān jiàng xià le qīng pén tè dà bào yǔ.

It was originally a cloudless sunny day when I went out in the early morning, but the sky suddenly changed in the afternoon, and there was a heavy downpour amidst lightning and thunder.