Midway through his band's 100-minute set at a sold-out Riverside Theatre, Justin Vernon paused and offered up a cheery greeting: "Happy Bon Iver Day!"

The Eau Claire native, who operates as Bon Iver's sole creative force, wasn't kidding. Prior to the band's two-night, tour-opening stand in Milwaukee, mayor Tom Barrett proclaimed Friday, July 22, "Bon Iver Day" in recognition of the frontman's strong ties to both city and state.

Fittingly, Vernon, 30, dressed in a plaid button-up and sporting a thick beard, looked the part of the average Wisconsinite, as though he'd just wandered into the venue after a long hunting trek in the North Woods.

While the singer's much-lauded 2008 debut, "For Emma, Forever Ago," might have projected a similar lost-in-the-wild vibe with its wintry sound and over-mythologized creation story (Vernon recorded the album alone in his father's hunting cabin shortly after a splitting with a girlfriend), the group's latest, simply titled "Bon Iver," is a much warmer, more expansive affair.

To recreate these lusher sounds, the singer employed a cast of eight backing musicians, many of whom played multiple instruments. The sprawling crew, which has multiplied in size like mogwai exposed to water since Vernon's first tour, utilized a trio of keyboard rigs, two complete drum kits and all manner of brass, including contrabass saxophone, french horn, trumpet and trombone, to flesh out the new material and, on one occasion, to breathe new life into an old number.

If "For Emma..." evoked a snow-covered landscape, recent tunes like "Holocene," augmented here by avian chirps of sax, sounded like spring finally settling in. Even the song's title — taken from the geological term for the era that followed the Wisconsin glaciation — reflected this shift. On "Beth/Rest," a love-it-or-hate-it slice of '80s yacht rock that called to mind the likes of Bruce Hornsby, Vernon laid out his latest mission statement even more bluntly, singing, "I ain't living in the dark no more." These warmer, more optimistic tones even wormed into "For Emma's" "Flume," which opened as an introspective acoustic ballad and closed as jazzy bit of art-rock.

Simple-but-effective stage lighting further added to the performance, bathing the collective in bluish hues on a dreamy "Michicant" and highlighting the ferocity of a snarling "Blood Bank" by igniting the musicians in fiery reds.

Vernon, drifting further from his solitary folkie image by the day, continued to carve a more exploratory path as the evening progressed, allowing songs to build, surge and recede as naturally as ocean tides. "Hinnom, TX," for one, opened with an atmospheric violin solo then gradually coalesced into a towering wall of sound as the band layered on all manner of instrumentation (muffled drums, liquid guitar chords, deep sax, etc.). "Perth," meanwhile, sounded even more massive live, metamorphosing into a swirling bit of psych-folk around the powerful thump created by the band's dual drummers, whose thunderous output on the tune sounded like particularly rhythmic pachyderm keeping time. During the encore, Vernon further highlighted his growing ambitions as he transformed Bjork's "Who Is It" into kaleidoscopic folk number complete with breathless beat-boxing by bandmate Reggie Pace - more art-folk than folk art, as it were.