Arctic rain?

The problem is that this is in April, all the previous rains were in June/July/August/September (read: summertime @ northern arctic zone)

Now only 2001 and 2010 have seen rain in April and May, so yes, it's a signal things are changing the last decades. It's getting warmer earlier in the year and that brings rain instead of snow.

that was to proof that raining in arctic has been happening all the time, where the OP said he's never heard of it.

The report said it's just a 3 minute rain shower, the data I find will only record events >0.3mm, which a 3 minute shower probably wouldn't count.

The first article I gave however suggest based on 25 years of data, that there will be a 40% increase of rain on snow in the next 100 years. The 25 year data might not be enough to make an accurate prediction.