If you follow the links, especially
to map 1, you see one version of how US dialects are divided. This map asserts
there is a 'Western' dialect zone; other maps extend Midlands into the west.
Within the understandings of this site, my dialect, then, becomes 'Western'.
As for the Northern Cities Vowel Shift,
this page covers it rather fully in a section lower down.
My command of phonology is insufficient to
give a clear description of what is happening. This is something I've only heard
of, and not experienced personally.