There’s something about songwriter Neko Case that makes people use a lot of F-words to describe her. Among the most frequent: fiery-haired, funny, fierce, fabulous, foxy, and foul-mouthed. On some level, all of these adjectives are accurate, but they don’t provide a complete picture, or even scrape the surface of Case’s complexity and influence. At 40, she’s hitting her stride, both as a solo artist and as one of the most called-upon collaborators in indie-pop, alt-country, and rock.

Case is, quite literally, a force to be reckoned with, as virtually everyone who has ever seen her perform live can attest. Her most recent album, the aptly-named 2009 alt-country beauty Middle Cyclone, is her strongest yet. An urgent, lushly orchestrated effort, its imagery, appropriately enough, evokes some of nature’s richest tricks and treats. Fittingly, Case describes nature as “the closest relationship I have.” The album brims with life, building so much momentum that the record reaches its conclusion well before you’re ready for the experience to end. But Case dismisses the notion of a grand plan on her part in sweeping the listener from start to finish.

“Not my intention, so much as a lucky accident,” she says. “I can hope for it, but that does not mean it will happen, but I try as hard as I can to steer it that way.”

Case’s primary co-pilot for this album wasn’t another musician, but rather Pulitzer Prize-winning author Annie Dillard, whose books served as Case’s main influence while crafting Middle Cyclone. The two share a similar writing style: dry, bemused wit mixed with genuine admiration and appreciation for nature and history. Each is plainspoken and concise, but can craft sentences that are emotional, vivid, and layered with subtext. In fact, one of the best lines Case has ever penned can be found on this album, her haunting alto promising, “Next time you say forever, I will punch you in the face.” Blunt and beautiful.

It is a style that has become Case’s trademark, made all the more poignant when matched with her soaring vocals. If she and her songs seem a curious paradox of tough-yet-tender, well, it’s because that just might be who she is. She has excellent survival skills, having left home at 15, eventually winding her way from Tacoma, Wash., to Vancouver, B.C., to attend art school when she was 24 years old. She’s been an artist, a drummer, a go-go dancer, and likely a vast assortment of other jobs that never made it onto the press releases.

When asked if she experienced a lot of rejection early, Case acknowledges she had, and it wasn’t easy, but maintains she faced something much harder.

“Poverty,” she says. “That’s always the ball-stomper. Some days it hurts, some days it doesn’t.”

It’s this kind of weariness that infuses Case, and her lyrics, with that core of strength. It’s evident on her first album, 1997’s The Virginian, but it wasn’t until 2002, following the release of her third album, that Case’s career paired traction with speed.

“People started coming out in larger numbers after Blacklisted,” Case recalls. “That’s when I got a second of being on the radar.”

Simultaneously, Case was also finding success as a quasi-member of the Vancouver-based power-pop band the New Pornographers. Case has recorded and toured with the band off and on since their 2000 surprise indie hit, Mass Romantic. In fact, she’s spent a substantial part of the last year touring with the group in support of its fifth release, 2010’s Together. She’s also one of the most sought-after vocalists in the industry, wracking up more guest spots than most rappers. But the majority of her moonlighting is reserved for a select group.

“I work with people I know, if I have time, which these days is seldom,” she says. “[The New Pornographers, Sarah Harmer, the Dodos] are family, and we already spend a bit of time together so it’s a little easier.”

Case’s busy schedule seemed to take its toll when, citing exhaustion, she postponed a Charleston show last August. At that point, Case had been on the road for almost two long years. Now she’s back, focusing on smaller tours, like this mini one throughout May.

She’s rested, ramped up, and, as evidenced by her Twitter feed, ready and willing to raise a little hell. Chief among her most recent grievances: the Esquire article that demanded to know why Tina Fey, arguably the most culturally significant funny person of the 21st century, won’t accept that she’s “hot.” Case, whose own looks have often taken precedent in the media, calls the situation “sad.”

“Tina Fey has nothing to prove to anyone,” Case says. “It’s an undisputed fact. Why is ‘hot’ even discussed? It makes me depressed, which of course will make people say ‘lighten up,’ which then makes me more depressed because I can only begin to imagine how hard she works and has worked. She deserves better, all people do, men and women.”

Allow another F-word to be added to the arsenal of Case adjectives: Freaking awesome.