It’s Thursday on Friday.

Miller Symphony Hall presents The Last Thursday Band as part of its “Jazz Upstairs” series, 7:30 p.m. Sept. 8, Rodale Communioty Room, Miller Symphony Hall, Allentown.

The ensemble consists of Brian Bortz, bass; Lou Czechowski, keyboards; Vicki Doney, vocals, and Daniel Gonzalez, drums and percussion. Chet Brown will join the group on vocals.

Bortz says the band is a product of serendipity that “morphed organically into what it is.”

He and Lou Czechowski have been playing together off and on for some 35 years. Bortz recalls, “I was playing at Hotel Bethlehem with another group and they asked us to do a Thursday gig.”

That was the inception of a group with Bortz, Vicky Doney, and the late Eric Doney. In looking at the 2011 schedule, Bortz recalls, “It was the last Thursday of every month. Hence, the name of the band.”

Czechowski became keyboard player and, in 2012, they added a drummer-percussionist. The band recorded a live CD at the Deer Head Inn, Shawnee-On-Delaware, with Paul Wells, their original drummer. “Finally, we added Daniel [Gonzalez] last summer. Lou and I had met him playing with Hector Rosado,” says Bortz.

Over the past year or so, Vicki Doney has been spending more time in California, where she’s from originally, and Brown has become the ensemble’s vocalist. For the “Jazz Upstairs” performance, both vocalists will accompany the band.

When asked what the audience could expect, Bortz says, “We’re primarily a jazz group, but we cover a wide range. We do everything from bebop and swing to Spyro Gyra. We do a lot of pop now with Chet [Brown], some R&B, some Sinatra, as well. Daniel brings a rich background in Latin music as well.” So, audiences can expect a smorgasbord of jazz-based entertainment.

As for the musical pedigrees of the group, Vicki Doney is well-known as a vocalist and pianist. She’s performed with Bob Dorough, among others, as well as at the opening ceremonies of the 1984 Olympics.

Czechowski studied at Moravian College and Berklee College of Music. He’s played Canada and Europe and in the United States in Atlantic City and Las Vegas, along with numerous gigs in the Lehigh Valley.

Gonzalez studied at the University of Nevada at Las Vegas and received two degrees from Mercer College. He played in United States Army bands and has performed from his New York base throughout the region.

Brown teaches at the Lehigh Valley Charter High School for the Arts, Bethlehem. He’s performed for decades in the Philadelphia area in many genres. He has also done voiceover work for Philadelphia media.

Bortz has been playing bass and guitar professionally for more than 30 years. Local music lovers may have heard him with the Fusion Jazz Trio and at times with the Philadelphia Funk Authority and the Eric Mintel Quartet. Bortz has played many genres and has numerous recording credits.

Tickets: Miller Symphony Hall Box Office, 23 N. Sixth St., Allentown; millersymphonyhall.org; 610-432-6715