Weather Report and Return to Forever, along with the Mahavishnu Orchestra, dominated jazz-rock fusion in the early '70s. Not only did these groups adopt the amplifiers and beat of rock 'n' roll, they followed the rock model of stable, cooperative bands rather than the usual jazz model of a leader and revolving sidemen. This resulted in cohesive, exciting ensemble playing.

Weather Report has been the only one of these bands to maintain stability, and it has paid off in a series of steadily maturing albums. Keyboardist Joe Zawinul and saxophonist Wayne Shorter founded the group in 1971. Bassist Jaco Pastorius joined in 1976; drummer Peter Erskine in 1978; percussionist Robert Thomas Jr. in 1980. The resulting rapport is obvious on the quintet's latest album: "Weather Report" (ARC/Columbia, FC 37616). The album is marked by a surprising restraint; all five musicians make their points with subtle moves rather than grand gestures.

This is most apparent on the two lovely ballads, "Current Affairs" and "Speechless." Zawinul has written melancholy melodies, draping the background of the songs in shifting synthesizer textures that create the proper rainy-day moods. In this setting, Shorter's gorgeous tenor sax brings out all the universal loneliness of someone overcome by romance. Rather than showy phrases, the well-disciplined Shorter lets his horn lapse into introspective fades and pauses before gathering strength to go on. By sliding his bass strings, Pastorius extends these fades into the depths of his instrument.

More than anyone else, Zawinul has recognized that the synthesizer is a completely different instrument from the piano. Unlike the Hollywood sound effects that many synthesizer players employ, Zawinul has invented a musical vocabulary that works in the service of the emotions. He uses squiggly lines that marry the assets of drone and rhythm. He shapes notes so they start small, swell to fullness and then patiently contract. He creates sheets of sound--droning background chords that never tire because the synthesizer retains its buzzing edge indefinitely.

Shorter and Pastorius have absorbed these and other musical strategies from Zawinul and adapted them to the saxophone and electric bass. Zawinul--who once wrote "Mercy, Mercy, Mercy"--still writes catchy melodies, and he will often have several instruments carry a bouncy melody line over an energetic percussion pattern, while others create swelling, droning tones in the background or twist squiggly rhythms underneath. These different roles rotate among Shorter's sax, Pastorius' bass and Zawinul's various keyboards. This rotation is achieved most effectively on "Volcano for Hire," which also boasts a snappy melody and an African rhythm charge from Erskine and Thomas.

Weather Report's exciting tour last summer showcased an encouraging democracy in the band on stage. On the new album, however, only one Wayne Shorter tune and one group composition counterbalance the seven Zawinul compositions. Shorter's "When It Was Now" features halting, stop-and-go bursts from the saxophone against a slow but inexorable march from the band. Jaco Pastorius--who performs with his own band at Blues Alley this week--apparently used up all his compositions on his entertaining but non-compelling solo album last year, "Word of Mouth." Zawinul has composed three captivating melodies for the two ballads and "Volcano for Hire," plus very ambitious electronic constructions for the three-song suite "N.Y.C." The suite captures the new sounds of an urban environment that is becoming less mechanical and more electrical all the time.

Three-fourths of Return to Forever--Chick Corea, Stanley Clarke and Lenny White--have reunited as the core for a special recording project: "Echoes of an Era" (Elektra, E1-60021). The era they hoped to echo was the late '50s when be-bop and cool jazz merged into tasteful renditions of standards. The new record tackles songs from Billie Holiday, the late Thelonious Monk, Duke Ellington, George Gershwin and a new one from Corea. Pianist Corea wrote the arrangements; drummer White produced, and bassist Clarke was joined by trumpeter Freddie Hubbard, saxophonist Joe Henderson and vocalist Chaka Khan.

With all this talent, you might expect a magnificent record. As a result, the disappointment is all the keener. Rhythm & blues vocalist Khan sings on all nine tracks and proves totally inept at jazz singing. Her tight-throated, metronomic reading of "Them There Eyes" may have Lady Day spinning in her grave. A vigorous rock belter on her own records, Khan has no sense of rhythmic or textural subtlety. The same problems afflict White, a slam-bang fusion drummer who proves incapable of true swing. His tick-tock drumming flattens out the syncopation of the rest of the band. The other players perform commendably, but with awkward vocals at the top and lifeless drumming at the bottom, theirs is a hopeless task.