Umphreys McGee keyboardist Joe Cummins has officially joined the Outside Lands lineup. Cummins will sit in on Hammond B3 and Wurlitzer with the local band Big Light on Sunday, August 30. The Umphreys McGee co-founder attended last years festival as a fan and sat in with Big Light during a festival pre-party. As previously reported, Outside Lands will return San Franciscos Golden Gate Park from August 28-30. Other artists scheduled to perform include: Pearl Jam, Dave Matthews Band, Tenacious D Ween, Modest Mouse, Thievery Corporation, Tea Leaf Green, the National, Black Eyed Peas and Tom Jones.