If you tuned in to WRTI-FM (90.1) between 10 p.m. and 2 a.m. Friday night, you might have heard singer-songwriter Lili Añel serenading host J. Michael Harrison with a soulfully reimagined "Happy Birthday," Philadelphia Jazz Project director Homer Jackson dropping by to promote the organization's Jazz Appreciation Month book raffle, saxophone great Odean Pope, bassist Gerald Veasley, and drummer Cornell Rochester reminiscing about their days as a trio, or simply the eclectic mix of music that Harrison has long touted as "your bridge between bebop and hip-hop."

That's a typically atypical Friday night for Harrison and The Bridge, the show he's hosted on the Temple University radio station for 20 years. "I always say that you need to listen for a month or two to really get a feel for what the show is," Harrison said a few nights later at a University City Starbucks. "From week to week, it can be really different, so if you tune in once you might think it's a poetry show or a jazz show or an interview show. That's what I want to bring to the table: you can't anticipate what it's going to be. It's beautiful chaos."

To celebrate his two decades on the air, Harrison will take over the Kimmel Center's monthly Sittin' In series for a performance by the reunited Odean Pope Trio with Veasley and Rochester. The three haven't played together since 2005 at a festival in Germany, and their last (and possibly only) Philly gig was decades ago, when superstar bandleader Sun Ra -- who died in 1993 -- was in the audience. In addition to the concert, Pope will receive the Mid-Atlantic Arts Foundation's Living Legacy Jazz Award, and Harrison will be named one of the Jazz Journalists Association's 2017 Jazz Heroes.

"I'm already designing a cape," Harrison joked about the Jazz Hero designation before going in a more serious vein. "It's always great when folks believe in what you do. It offers a certain level of validation when you question yourself at times, or other people raise their eyebrows. It's fuel to keep pushing."

Looking back over the show's long run, Harrison recalls a number of what he refers to as bright moments. They include a breathtaking early appearance by Jill Scott at a time when the future Grammy winner was a rising star on the local poetry scene; the time he invited a former Tuskegee Airman to program a show with the music he would have listened to in the cockpit of his plane; convening sax greats Pope, Byard Lancaster, and Prince Lasha to play together in the studio; or flutist Dave Valentin, who died last month, inadvertently admitting live on the air to a relationship with singer Angela Bofill.

"It's really special when you reflect a little bit on some of the great artists that have come through," Harrison said. "There's been a lot of rule-breaking and risk-taking. I feel really fortunate that I've been given the opportunity to make this madness happen every Friday night."

There were a lot of small signposts along the way that led the North Philly native to his calling on the FM dial: the eighth-grade history teacher who complimented him on his speaking voice and urged him in vain to read poetry in front of his classmates ("During the gang-war era in Philadelphia, I didn't see myself standing on stage doing the Edgar Allan Poe thing."); the friends and family members who recognized his passion for music and encouraged him to channel it into something productive.

"I was the guy spending every paycheck at 3rd Street Jazz and Radio 437," Harrison said, citing two long-defunct Center City stores. "This is passion for me, hearing something that touches me and believing it may touch other folks as well. I want to find that rare thing that maybe you haven't heard and try to get that to you, but also give you an interesting experience on Friday night. I'm blessed to be able to do that."

Sittin’ In: The Bridge's 20TH Anniversary. 8 p.m. Wednesday, SEI Innovation Studio, Kimmel Center, 300 S. Broad St. Tickets: Free.
Information: 215-893-1999, www.kimmelcenter.org.