I had interpreted a contiguous run of base pairs to be a helix, but after looking at a few structures in VARNA, I realized that some of the "helices" could be considered one helix with a few bulges. Sam gave some good examples:
You have continuous on one side, but not the other:
Alignments where a helix is continuous in most sequences, but bulged occasionally:
In the above case, what is a helix could be subject to arbitrary change, just by adding one sequence with a bulge.