I am speculating that "WEM UHF 2" is either old nomenclature or their slang for one of the interop channels. It could be anything. Many non-radio savvy public safety personnel use the term "UHF" for anything other than their normal system (so it could be digital, trunked, etc.)
Try searching the closest WISCOM tower sites and see if any of the interop/tactical talkgroups pop up.
I would also put in all of these (including VHF) and take a listen
Scanner Frequencies and Radio Frequency Reference for Conventional Interoperability (Wisconsin)
www.radioreference.com
It is also a possibility that the channel/system they are using is low-power and you are too far away from the concert to hear them.
Good luck!