But can you say for sure it was NOT due to global warming...

But can you say for sure it was NOT due to global warming (whatever the cause?).

Perhaps it happens more often with warmer air? (purely a hypothesis...)

As for 70 years ago, so what? Claiming one weather event as evidence for or against global warming is baseless. Just leads to silly tit-for tar arguments like on this thread.

Like the stock market, it's the Trend that's your Friend.