[1] After a short stint in the Elite Ice Hockey League with the Dundee Stars, Southorn returned to the ECHL with the Fort Wayne Komets in the 2013–14 season.

On August 5, 2015, unable to secure an AHL contract, Southorn returned on a one-year deal for a second stint with the Fort Wayne Komets of the ECHL.

[3] In the following off-season, Southorn left for abroad as a free agent, signing a one-year deal with Russian second division club, Torpedo Ust-Kamenogorsk of the VHL on August 12, 2016.

On July 24, 2018, Southorn left Kazakhstan after two seasons and agreed to an initial try-out contract with German club, the Straubing Tigers of the Deutsche Eishockey Liga (DEL).

[6] In the 2018–19 season, Southorn collected 17 points in 21 games before leaving the club to accept a European contract with HC '05 Banská Bystrica of the Slovak Extraliga on December 10, 2018.