While June is not expected to run colder than normal a strong cold front mid week is expected too cool the air enough for snow to fall. Accumulations are all over the place in the models but it is expected late week, afterwards the temperatures are expected to quickly shoot back into the 20s.
http://www.wunderground.com/blog/Mikeman444/comment.html?entrynum=84
So far we have documented 6 thunderstorms, most were quite weak as it is still early in the year for supercells.
Video of a close strike on May 31st
AlbertaWX - Central Alberta Storm Chasers 