I'm excited for the second half of UW's Week of Jazz (through Mon April 19, www.music.washington.edu/jazz20), continuing with trumpeter Cuong Vu's two-evening stand (Thurs–Fri April 15–16). I wrote about Vu last week, but I neglected to mention that he's corralled some intriguing openers; two bands, Operation ID and the sax-and-drum duo Bad Luck, open for Vu on Thursday, while Goat, led by Greg Sinibaldi, opens Friday. I love the combative contrast of Sinibaldi's breath-controlled synth with Zach Stewart's looped guitar patterns.

The festival concludes with a performance by Bill Frisell (Sun April 18, Meany Theater, UW Campus, ­3 pm, $10/$15). A stylistically omnivorous guitarist who ranges from bluegrass to elegant loops, Frisell collaborates with top-notch students from the UW jazz program, trombonist Stuart Dempster, and Vu.

Also don't miss Seattle Repertory Jazz Orchestra. Careful transcriptions from records and lead sheets don't dampen the vigor this group brings to now-venerated masterpieces. While I'm salivating for their performance of Duke Ellington's Far East Suite in June, catch their revival of the legendary Miles Davis LP Birth of the Cool (Sat April 17, Recital Hall at Benaroya, 200 University St, 7:30 pm, $21–$38/$15 for those under 25). French-hornist Tom Varner and pianist Bill Anschell team up with regular members of the SRJO for "Jeru," "Moon Dreams," and other Cool-era tunes that smoothed out the jumpy, overcaffeinated melodies of bebop with chilled-out French horns and tubas.

Elsewhere, saxophonist Wally Shoup helms a modified version of his trio, a combustible group he rightly describes as "heavy chamber jazz" (Sat April 17, Chapel Performance Space, 4649 Sunnyside Ave N, 8 pm, $5–$15 sliding scale donation). Shoup and pianist Gust Burns wed blues-fired volcanic free jazz to compact forms. Expect some extra aggro as Monktail Creative Music Concern linchpin Mark Ostrowski fills in for their stalwart drummer (and sometime French-hornist) Greg Campbell. Later that night, Hardcoretet (Sat April 17, Faire Gallery, 1351 Olive Way, 10 pm, free) serve up trenchant, funk-filled improvisations that update the wide-­ranging sound of Return to Forever without getting abstruse or bloated.

The spirit of improvisation persists in classical music as well, though at an unlikely instrument: the organ. As the tradition of improvising keyboardists epitomized by Beethoven (and bloated by Liszt) waned, and publishers began serving up prefabricated concerto cadenzas for nervous (or busy) soloists, organists kept the flame of improvisation alight. Here, French organist Sophie-VĂ©ronique Cauchefer-Choplin (Tues April 20, St. James Cathedral, 804 Ninth Ave, 8 pm, $15 suggested donation) concludes a program of works by Cesar Franck, Louis Vierne, and others with something their classical confreres rarely perform today: an improvisation. recommended