Mellowing Jeff Tweedy Trades His Denim for Cords

The album’s opener, “Either Way,” begins with a characteristically cozy electric guitar, and Mr. Tweedy sings: “Maybe the sun will shine today / The clouds will blow away.” Jolly drums and a pastoral organ come in, plus feathery 70’s-era Randy Newman strings. But the song would still be flat-chested if it weren’t for a monstrous minor chord that creeps in: This album has a knack for getting curvy in all the right places.

Nevertheless, it’s still Wilco’s most syrupy-smooth record. The second track, “You Are My Face,” begins with a schmaltzy harmony (in which “sunshine” rhymes with “goldmine fulltime”). Thankfully, it only takes 90 seconds before the syrup gets replaced by grit, when the freshly added guitarist Nels Cline gnashes away.

How could one musician sound so much like chrome and margarine and gin? He’s a self-taught jazz guitarist who quotes Sun Ra and Garcia Lorca.

After a sprinkle of muddy and almost sappy blues, the second half of “Walken” becomes an electric, wave-your-Zippo extravaganza, interrupted only by Mr. Tweedy’s poignantly high-voiced epiphanies about a special little lady: “The more I think about it,” he howls twice, “I’m sure it’s you!” The piano player pounds, the drummer thrashes, and two guitars giddily wail like Lowell George (the Southern-fried Little Feat guitarist who liked speedballs and used a Sears & Roebuck spark-plug socket wrench as a guitar slide).

But Wilco’s guitars are at their most velvety on the album’s sleepy-eyed title track, where a lap steel tears up in the backdrop while Mr. Tweedy mumbles gloomy haikus: “With a sky blue sky / This rotten time / Wouldn’t seem so bad to me now.”

A sunnier haiku opens “Shake It Off” (“Sunlight angles on / A wooden floor at dawn / A ceiling fan is on”), which would be hugely bothersome if the song didn’t get so thunderous and tipsy after only two verses. The crusty, start-stop, cymbal-smashing spank of the “Shake If Off” chorus makes up for its sissy opening poetry.

It’s been 12 years since the band’s flannel-shirted barroom debut, 1995’s A.M., and they’ve rarely been as boozy as that song’s second half. But Sky Blue Sky is also Wilco at their clearest, airiest and most tender: Grateful Dead, eat your Californian hearts out.