Since improvisation is one of the defining elements of jazz, one of the greatest byproducts of the music’s art is the way its practitioners can come together on the fly and make great things happen. Most music requires scheming and rehearsing before things will sound OK, especially when a group of players are getting together for the first time, but jazz skirts those needs—though if a group is playing new compositions, coming up with arrangements and rehearsing certainly helps. Recently the superb guitarist Jeff Parker was contacted by the likewise gifted New York reedist Oscar Noriega about setting up an ad hoc concert date here. Noriega was traveling with his wife on a cross-country road trip and wanted to make a stop in Chicago on the way back home.