ALESSANDRO SOLCA WALTER TROUT Blues singer-songwriter-guitarist Walter Trout — who headlined the free, annual Morristown Jazz & Blues Festival in 2017 — will headline again this year, Sept. 17, outdoors on the Morristown Green. For information, visit morristownjazzandblues.com. The festival, now in its 12th year, used to take place every August. But it moved to September last year because of the pandemic, and with attendees enjoying the cooler weather, the decision was made to keep it in September. As usual, the festival will focus on jazz, early in the day, and blues later on. He is the sched…