The Harmonia Chamber Singers’ “Gaudete!” concert, originally scheduled for December 16, was postponed due to the first winter storm of the year. They will deliver the program instead on Sunday (Jan. 6), at the Blessed Trinity Church (317 Leroy Ave. in Buffalo), at 4pm. This is the group’s third annual advent and Christmas concert as one of WNY’s newest and finest performing ensembles. Their repertoire includes interpretations of some of the most beautiful a cappella music in the world under the direction of Robert Pacillo, who has also perfromed with the Buffalo Choral Arts Society and the Vocalis Chamber Choir. This will be the choir’s last concert until the spring.