"Heavy rain every once 50 years"?

The heavy rain caused by Typhoon No. 5 is falling in the Kyushu district.
The Meteorological Agency calls "heavy rain every once in 50 years" like every day. This way of saying may be a means of giving citizens awareness of heavy rain, but it seems like this is repeated every day, as if it were a story of a wolf boy.
Therefore, I think that the expression of "ragingly strong rain" is appropriate.
To the people, expressions that give fear should be avoided.