On June 23, 2002, about 1415 Pacific daylight time, a WSK PZL Swidnik PW-5 glider, N155TM, impacted trees short of the Paul Hoberg Airstrip (Q79) near Loch Lomond, California. The glider, owned and operated by the private pilot under the provisions of 14 CFR Part 91, was substantially damaged. The pilot, the sole occupant, received serious injuries. Visual meteorological conditions prevailed for the local area flight that departed a private dirt strip (Crazy Creek Soaring) in Middletown, California, at 1303. According to a tow pilot flying in the area, the glider pilot radioed that he was landing at Q79 because he did not have enough altitude to get back to Crazy Creek, and requested that someone from Crazy Creek Soaring pick him up. The tow pilot tried to reach Crazy Creek Soaring to relay the accident pilot's request for a pickup. When he couldn't, he attempted to contact the accident pilot, but received no response. The tow pilot reported that the accident pilot did not make any distress transmissions and sounded confident he would land at Q79. In a written statement submitted by the pilot, he stated that about 1345, in the vicinity of the Hoberg Airstrip, he encountered a "severe sink" and "struggled for +/- 30 minutes to gain altitude." According to the pilot, the altitude upon arrival was 3,750 feet (the airport elevation was approximately 2,700 feet). The last thing the pilot could recall was being on approach to the runway and experiencing "severe wind sheer/turbulence." A responding sergeant from the Lower Lake County Sheriff's Department stated that the glider came to rest between trees about 300 yards short of the runway on a southwesterly heading. At 1353, the automated surface observation system (ASOS) at the Santa Rosa Airport (STS), located approximately 24 miles southwest of the accident site, reported that the wind was from 140 degrees at 7 knots. At 1453, the same weather observation facility reported that the wind was from 140 degrees at 11 knots. The pilot reported in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) that he had accumulated a total of 540 hours of glider flight time, of which 200 hours were flown in the same make and model as the accident glider. In the accident report, under the section titled "How Could This Accident Have Been Prevented," the pilot indicated that he "should have landed when at 1,000 feet, attempting a thermal recovery from 300 feet is dangerous."