Ambushed by rainfall! ゲリラ豪雨

Mrs. Sunshine-Salaryman is fluent in English due to a partial upbringing outside Japan and we mainly communicate in English but mix it up a bit with Japanese to keep us on our toes. From her perspective it's convenient but also a bit dangerous since if she can't find the word in English easily she can just say the word in Japanese and I'm very likely to understand what she's saying. This could cause some inconvenience for her when she's talking to some foreigner who cannot speak Japanese since she's used to having an easy way out.

In any case, her English is basically perfect but sometimes she gets a bit hesitant and unsure and asks me what the word for something is. An exchange like this is not completely unusual:

Mrs. Sunshine: Salaryman, I'm forgetting all my English... What's the word again in English again for the sound that a raindrop makes when it's hitting a purple flower during a hot late summer night?

Salaryman: Uh, Sunshine... I don't think there's an English word for that you know, you just have to say the whole thing... Besides, your English is fine, don't worry! Why do you want to say that anyway?

Which brings me to the topic at hand. As you might have figured out, there's quite a few unique words in the Japanese language that basically are extremely hard to translate to English or just don't plain exist (hey, this is probably true for most languages though). My recent favorite Japanese word is ゲリラ豪雨 "Guerrilla rainfall". Guerrilla rainfall is sudden and intense rain when you least expect it, basically you getting ambushed by the sky. It's been frequently used in weather reports now during the rain intense last weeks (frequent rain in West and South Japan that is, not Tokyo).

I have the feeling that this word will never catch on in English...