The pilot said he monitored the ATIS while inbound to runway 19R and that the reported winds were from 230 degrees at 12 knots. While on downwind, the pilot said he observed a twin engine aircraft land, noting the crab angle for cross wind effects. The pilot stated that he did not hear the local controller provide 'gust advisories' while he was in the traffic pattern. The pilot said that about 50 feet above the runway, "we encountered a strong downdraft that brought us to (the) runway and back up to about 40 feet AGL." The pilot reported that he attempted to go around but that the aircraft contacted the ground near the runway edge and then left the pavement and ran into the grass area between the runways. The aircraft collided with several runway signs and sheared off the landing gear. Transcripts of recorded air to ground radio communications revealed that the aircraft was sequenced behind another aircraft and cleared to land at 1340:37. At 1341:39, the controller, in response to a request by another aircraft for the current winds, broadcast "wind two four zero at one two." The official weather observation taken immediately after the accident reported the winds from 270 degrees at 10 knots with gusts to 15 knots.