"Rise to Downpour", the last and longest track on the Vancouver duo Carsick's self-titled debut CD, is a wonderful instance of musical scene-setting. Opening with JP Carter's sputtering trumpet and sparse plucking from Dave Sikula's electric guitar, the piece gradually morphs into a sinuous melody that in turn becomes a moody seascape, all foghorns, lapping waves, and Echoplexed seagulls. I think there's a red-winged blackbird in there, too, and sandpipers; we might well be lost in the misty marshes of the Fraser foreshore.

And then the storm breaks. Sheets of white noise evoke squalls coming in from the sea; Carter's breathy trumpet plays the wind. A worrisome electronic drone hints that it's getting dark-and then the original melody returns, as the downpour subsides and the birds begin their frenzied evensong.

It's like a day's excursion compressed into 12 brief minutes. And its atmospheric strengths are typical of Carsick's output, although its structure isn't. According to Sikula, in a late-night telephone interview from his home, it's a rare instance of the two musicians plotting an elaborate scenario before venturing off into the improvisational unknown.

"Something that I've always noticed with the two of us is that we've never actually talked about the music all that much," the guitarist explains. "Generally, one of us will bring in an idea, and we'll just sort of play the idea, so it takes shape that way. It's not very often that we're telling each other what to do. If anything, it's more like we're trying to describe to each other what's happening in an abstract way.

"?'Rise to Downpour' is very definitely one where we discussed the mood of a storm, for example," he adds. "That comes across in that song. But in terms of the rest of the tunes on the recording, I would say that's the only one we approached that way."

Some of the other tunes are clearly structured. "High Over Sand", for instance, drapes Carter's wistful trumpet melody over a series of first-guitar-lesson chords. It's rare to hear such accomplished musicians playing so simply, but according to Sikula it's the only way the piece could work.

"The second we started playing it, I realized that was the way it should be," says the guitarist. "And that's something I've enjoyed from the beginning: that there's always been a certain patience and simplicity in the way we approach the material."

The two started playing together about four years ago, and since then their collaboration has resulted in a few interesting spinoffs, including their Drip Audio labelmates the Inhabitants, in which Carter and Sikula are joined by bassist Pete Schmitt and drummer Skye Brooks.

"Skye was a big fan of Carsick, and he used to come out and see us at the Sugar Refinery," Sikula recalls. "And one night he mentioned, 'Well, if you guys ever wanted to try to incorporate a drummer, I would be into that.' Around a year later, we formed the Inhabitants out of that idea, but it's grown into something completely different."

Just how different can be seen at Radha (728 Main Street) on Saturday (April 1). Fans of dreamy, atmospheric electric jazz will be intrigued by the Inhabitants' dub-style take on what, for want of a better word, might be called fusion, while Carsick will up the multimedia ante by bringing dancers Anne Cooper and Jennifer Clarke onboard.

It's not the first time the two have worked with dancers, and Clarke says that both Sikula and Carter are ideal collaborators. Just don't expect them to play "Rise to Downpour"-or, for that matter, any of the other tunes on their debut disc.

"They absolutely create a landscape, for sure," Clarke agrees. "But they don't tend to play their compositions when we dance with them. They've only done that once, and it didn't actually work out as well as it does when we improvise together, because then we're all creating the same thing."

In other words, what they create is fresh every time. But the expanded, interdisciplinary quartet has evolved a kind of predictable format, as Clarke explains.

"They influence what me and Anne do at the very beginning, more than anything else," she says. "As soon as they start to play, they create a mood right away. And then, often, we leave it. We enter the mood and it totally influences our improvisation, and then Anne and myself just get into a state and they follow us from there on."

Sikula agrees, and adds that working with dancers brings "an interesting variable" to a Carsick performance. "There've definitely been times when we've been surprised by where they ended up, and vice versa," he notes. "It really creates another dimension that's quite challenging but that's also quite engaging."

All four performers thrive on this kind of stimulation, however, and even if they bypass the rainy swamps of "Rise to Downpour" they'll likely lead us into other, equally evocative landscapes.