Weather Report reached their critical and commercial peak with 1977’s Heavy Weather, which hit No. 30 on Billboard's pop chart and was designated “jazz album of the year” by almost every publication, including the esteemed Down Beat. “Birdland” was a huge crossover hit, and the song remains one of Weather Report’s best: though propulsive and complex, it's also as catchy as a theme to a TV show. By this point, Jaco Pastorius’ restless bass playing had become an integral part of the group’s sound, and with this album he proved he could be lyrical (“A Remark You Made”) as easily as he could be explosive (“Havona”). One of the album’s touchstones is Jaco’s original “Teen Town,” which is driven by a thunderous bassline, as heavy and doom-laden as anything on a Black Sabbath album. Of course, this being Weather Report, the ricocheting percussion and frisky rhythms keep each song from getting too weighed down. Even as their melodies became more memorable, the group’s highest principle was movement. Whether the setting was soft or loud, fast or slow, they were always pushing forward.