Out of the Great Northwest, land of rain and Bill Walton, comes Heart, to play at the Capital Centre Sunday night.

Heart comes in following the recent release of its second album for Portrait Records (its fourth altogether), "Dog and Butterfly," a record sure to add to the sextet's already massive following and high sales.

Heart has managed to transcend its often-ordinary material by spotting each album with several very strong pieces (in this case, the title cut and "Straight On") and smoothing out the harder edges with soft vocal harmonies and deft arrangements. In fact, the album's title refers to the group's abilities to be both sordid and sweet.

Heart also subtly implies the one sure-fire grabber in rock music sex. Not that Heart is blatant like the Runaways or gross like Patti Smith. What Heart uses is a pair of Wilsons (leader Ann and younger sister Nancy) who steer between Linda Ronstadt's vulnerability and Grace Slick's more obvious lures. The effect is a half-innocent, half-provocative appeal that pervades its recordings and makes its concerts more exciting than might otherwise be expected.

It's ironic that sexuality plays the role it does, because Heart's separation from Mushroom Records (its first label and the distributors of "Dreamboat Annie" and "Magazine") was due in part to promotional materials that the band felt - rightly or wrongly - was in poor taste. Heart manages to be suggestive without becoming lewd or offensive, with a charm that reaches female aspirations (the vibes from the men in the band don't hurt) as well as male fantasies, communicating desire without any accompanying intimidation: a platonic sensuality everyone can enjoy.

"Dog and Butterfly" opens with a live "Cook With Fire," recorded in Memphis, a good example of Heart's musical strengths and weaknesses. On the strong side, an earthy plaintiveness seeps through the Wilsons' gutsy vocals, and they carry the audience with their energy and enthusiasm. Weaker is the song itself, which is nothing more than a straight power-chord progression and no stronger than most others of its type. Heart's live set on the "California Jam II" album is far superior, primarily because the instrumental interplay is cleaner and the tunes run closer to the studio versions. Still, all its live material suggests a band with some passion.

The slower songs, propelled by Roger Fisher's soaring guitar riffs and Howard Lesse's keyboards, envelop you in sound, and the rockers are solid and tight. Heart's problems, both on "Dog and Butterfly" and in the rest of its catalog, are its inability to produce consistently top-quality material and a seeming resistance to stretch out fully on its heavier tracks, which never really get off the ground and sometimes seem tight and flat. Strangely enough, on mid-tempo numbers like "Straight On" those lapses turn into advantages, with the restraint adding a pleasant come-on to the composition and giving it more depth than most of the harder songs.

Besides "Dog and Butterfly," Heart currently has a "Magazine" picture-disc "art work on the vinyl) selling briskly at $13.98 a pop, and the group should draw a big crowd to Largo Sunday. Their total body of work does not warrant particularly high praise, but their best stuff is too good to ignore. And their nearly subliminal sexiness can be quite intoxicating to anyone willing to accept its substantially innocent form.

While Heart draws the lion's share of fans into the Capital Centre this weekend, there will be a smaller but potentially more interesting show in town at the Warner Theater. Jean-Luc Ponty unpacks his electric violin in support of his latest release, "Cosmic Messenger," and the stage should ring with the richness of his jazz-rock fusions.

"Cosmic Messenger" continues the French-born musician's variations on influences as diverse as Stephane Grappelli, John McLaughlin, Elton John and Frank Zappa. Anyone who's played with both the Mahavishnu Orchestra and the Mothers of Invention is not your everyday fiddler, a point "Cosmic Messenger" strongly underlines.

Though Ponty's compositions tend to blend into sameness, on this album it seems more by design than lack of initiative. His style remains brisk and full, and his dexterity does not detract from his tonal clarity. Ponty's traditional jazz background pulls his material away from structured arrangements and toward the improvisational: He sets up his pulsing backbeats with layers of guitars and keyboards and then rides over and through them with a hypnotic speed.

"Cosmic Messenger" seems more of a whole than some of his earlier albums that showcased various tunes and merely filled time with others. His newer approach keeps any one track here from being especially memorable (though the title cut, "Puppet's Dance" and "Ethereal Mood" all have their moments), but it fuses the entire work into one continuing piece. Overall, it's a bit less exciting than his best individual cuts ("Aurora" springs immediately to mind), but as an album, "Cosmic Messenger" is more consistent.

Anyone whose memories of the violin are dominated by pushy teachers and expectant parents should try to see Jean-Luc Ponty Sunday. He might make you forget all about screeching scales and let you concentrate on images of flight and fancy.

THE RECORDS

HEART - Dog and Butterfly (Portrait, FR 35555)

JEAN-LUC PONTY - Cosmic Messenger (ATLANTIC, SD 19189)

THE CONCERTS

HEART - Capital Centre, Sunday night at 8, tickets $6 and $7, reserved.

JEAN-LUC PONTY - Warner Theater, Sunday night at 8, tickets $7.50, reserved.