On August 2, 2015, about 1500 mountain daylight time, a Schleicher ASW 20B glider, N20YZ, experienced a loss of lift during cruise flight, and impacted terrain near Logan, Utah. The private pilot owned and operated the glider under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. The pilot was seriously injured. The glider sustained substantial damage throughout the fuselage and wings. Visual meteorological conditions prevailed for the local flight that departed the Logan-Cache Airport (LGU), Logan, at 1430. No flight plan had been filed. The pilot reported that he was participating in a mountain flying training course when the glider encountered a strong downdraft while maneuvering near a mountain ridge, and lost lift. The pilot was unable to arrest the glider's rate of descent, and the left wing impacted a tree. The pilot reported no preimpact malfunctions or failures that would have precluded normal operation of the glider. Postaccident examination of the wreckage revealed that the left wing was completely separated from the fuselage, and the right wing partially separated from the fuselage. The empennage forward of the vertical stabilizer was separated from the fuselage.