At the conclusion of a cross-country flight, the glider pilot arrived at his intended destination and entered a normal left-hand traffic pattern to runway 23R. The pilot reported that he observed the wind conditions on the downwind and base legs, and he maintained a normal traffic pattern. The wind was from 190 degrees at 10 knots. The initial approach to the runway was normal. However, the pilot said that on short final approach he suddenly encountered a "very heavy downward sink, accompanied by a sharp drop in IAS [indicated air speed]." The pilot responded by retracting the wing spoilers and adjusting the glider's pitch to maintain the requisite approach speed. The downdraft continued, and despite the performance capabilities of his glider the pilot was unable to glide to the runway. The pilot turned to avoid a set of power lines, and a wing contacted the ground. The glider touched down hard on the flat open terrain several hundred yards short of the threshold. As the glider came to a stop, the fuselage severed in front of the vertical fin, the horizontal stabilizer broke in half, and the fuselage was deformed.