The trumpeter Tom Harrell has been doing this a long time, through various schools and vogues: He can play slow and fast and in between, sometimes all within a single line. But his improvising is always temperate and proportionate. He keeps you on the hook, but doesn’t shout, doesn’t stop the clock. Plenty of improvisers are specialists in now-ness, revealing a solo as a series of events, or present-tense flashes. With Mr. Harrell, it’s all one event. He’s always processing ahead and behind, and you feel as if you’re hearing the whole of the narrative at all times, from was to is to will be.