Thundercat performs at the Stern Grove Festival in San Francisco on Aug. 8, 2021. Matt Pang/STAFF

SAN FRANCISCO — Concertgoers turned out in colorful variety Sunday to see Los Angeles’ Thundercat perform at Stern Grove Festival. Despite the overcast sky, the tree-lined natural amphitheater was packed. Ladies in leather rubbed elbows with dignified dashiki-clad gentlemen; evidence of the mix Thundercat attracts. A superfan in gold leopard-print robes embodied the cat’s pajamas.

The sharp-dressing Thundercat (Stephen Bruner) walked onstage sporting a sparkly blue shirt and bleached dreads. He wasted no time eliciting manic staccato runs from his sunburst hollow-bodied bass. Bruner’s trio launched into the gentle but flashy “Lost In Space / Great Scott / 22-26.” He took the lead with some fast fretwork. “Just let me know, so I can go, I can feel a pulse,” he sang in his matter-of-fact falsetto, expressing his readiness to “go and start the show.”

Keyboardist and frequent Thundercat collaborator Dennis Hamm chimed in with bright, shimmery accents in the upper register. Hamm held to a loose melodic through-line, using subtle arpeggiated chord shifts. The song unfolded ethereally, turning into an extended free jazz jam. Toward the end of the song, Bruner fired off an unhinged bass solo, processed to sound like a distorted clavinet keyboard.

Thundercat performs at the Stern Grove Festival in San Francisco on Aug. 8, 2021.

On homage “I Love Louis Cole,” Bruner shouted a big thank you to his friend. “This song is about Louis Cole putting up with me,” he shared during the intro, referencing a wild past spent partying. The song was a key track on last year’s It Is What It Is. Performed live, the high-adrenaline song expanded into new improvisational dimensions. Through several instrumental tangents and a climactic breakdown, Bruner soloed extensively over the watertight drumming of Justin Brown.

The full virtuosity of the musicians was unleashed mid-set on a reactive Chick Corea tribute. “Without Chick Corea, none of us would be here today,” Bruner said, referencing Corea’s passing earlier this year. The performers’ talents raged as they meshed cohesively in a cacophonous spree. Hamm’s heavily reverb-laden organ cut through the chaotic arrangement. In a gestalt moment, the trio did more than trade solos, constructing an impressive wall of sound.

As a pop artist, Thundercat has carved out his place with brief tunes that can be described as quirky contemporary soul. Performing last year in Oakland, the same trio focused on short, faithful renditions of album tracks. In contrast, Sunday’s concert was a showcase for Thundercat’s improvisational capabilities. At Stern Grove, his jazz background and instrumental prowess superseded his pop sensibilities. Brown and Hamm kept pace with their own expertise and tireless explorations.

Thundercat performs at the Stern Grove Festival in San Francisco on Aug. 8, 2021.

Crowd-pleasing refrains did emerge occasionally from the outpouring of free jazz libations. Fan favorites like “Friend Zone” and “Tron Song” arrived in scaled-up versions. The band successfully blended both worlds on a locked-in performance of “Dragonball Durag.” On the deceptively intricate song, the band effortlessly fused sophisticated chord changes to a consistent groove. “Durag’s” great hook was enhanced by the band’s synchronized attention to detail, resulting in an expert showcase.

In something of a departure from his mainstream appeal, Thundercat went full-blast musically. Bruner and company are such driven students of music that their performances are always instructive. Elements of fusion and the avant-garde crept in with a scattering of influences. Quotes from Mahavishnu Orchestra surfaced temporally before ducking back down into the manic mix. Though the group looked slightly out-of-synch at times, they powered through for a fascinating and uplifting presentation.

Cassowary performs at the Stern Grove Festival in San Francisco on Aug. 8, 2021.

Opening the show was Cassowary, a young Los Angeles artist. At center stage, Cassowary, whose name is Miles Shannon, rocked the tenor saxophone for several runaway solos. Blending an array of modern and established styles, he created sultry jazz for limo rides and drinks on ice. Between sets, the charismatic DJ Shortkut spun discs among three turntables. Shortkut started with some chunky disco, then elicited singalongs with “Ain’t No Mountain High Enough” and a Stevie Wonder cut from 1980.