The helicopter pilot reported that while climbing out of a canyon at 30 knots indicated airspeed, about 50 ft above the ground, he felt a "hard vibration" in the cyclic and collective controls. He then saw that the airspeed gauge was reading zero knots and he felt the helicopter was being pushed down. The torque indicator rose to 120% without any cyclic and collective control input. He applied right cyclic, lowered the collective, applied right pedal to counter the torque, and turned the helicopter downslope and into the wind. He applied forward cyclic to better match the downslope of the terrain and raised collective, but the helicopter impacted terrain. The skids impacted the ground first followed by the main rotor blades. The helicopter rotated 180º to the right before coming to rest downhill, on its right side. Shortly after, a post impact fire ensued. The helicopter was destroyed during the postimpact fire. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. The pilot reported that the winds were gusting up to 30 knots in the canyon, "changing direction every minute or so."