HI John, 

Interesting! It is likely that this tree had a bit of winter damage. This past winter we had a dramatic downswing in temperatures around mid-January that damaged many trees in the state. As the tree leafed out this spring, the vascular tissue would have undergone additional stress and failed to keep up with the increased demands for water and nutrients, causing rapid death of sections of the tree. 

You could also have a bacterial canker infection. Keep an eye out for the symptoms listed in this article (Managing bacterial canker in sweet cherries: What are the options? - MSU Extension). If you see cankers develop, you can prune them out this summer. 

Best wishes,

Yes, going forward I would recommend pruning off the dead wood this summer. It will not produce new growth next year. 

Best,