Tampa light-rock station Mix 100.7 just gifted Tampa Bay music lovers with an early Christmas present. Bubbly singer-songwriter Colbie Caillat is joining the lineup for the station's Acoustic Christmas concert, scheduled for Dec. 13 at the Mahaffey Theater in St. Petersburg. Caillat joins an already strong lineup, including the Goo Goo Dolls, the Fray, Michael Franti and ZZ Ward. Caillat will no doubt dip into her 2012 holiday album Christmas in the Sand for this one, but maybe she'll also break out summery singles like Realize, Fallin' For You and Begin Again. Tickets to the show start at $39 and are on sale now. For details, see tampabaysmix.com.