So... to answer my own question about Northern teams in the Super Regionals, I used stats from d1baseball.com all the way back to '03. Before I list the results, one caveat: I did not include schools that could likely be argued as regards to their location whether the climate would classify them as 'Northern'. Those could include schools like UNC, NC St., Louisville, Coastal Carolina, Eastern Carolina, TCU, and Oral Roberts. A couple I am not entirely sure of the location (E. and C. Carolina). Other than those potentials, the rest would undoubtedly get the classification of 'Northern' schools for purposes here, I believe.
'11 - 1 Northern school - UConn
'10 - 0 Northern schools
'09 - 0 Northern schools
'08 - 1 Northern school - Wichita State
'07 - 2 Northern schools - Michigan, Wichita State
'06 - 1 Northern school - Mizzou
'05 - 1 Northern school - Nebraska
'04 - 0 Northern schools
'03 - 2 Northern schools - Ohio State, SW Missouri
These are just Northern schools that made it to the Super Regionals. When we get to the CWS, I'll go through and see what I can locate there. Interesting stuff. Shows that in most years, at least one Northern school makes it to the Super Regionals. Nice anomaly this year of 3 schools, though when you look at the Regional rankings of the 3, Stony Brook was 4, and St Johns and Kent State were both 3s. So some great achievements for those schools to even make it this far.