Mammoth Lakes, California (tca/dpa) — Last month, Mariusz Wirga, a doctor in California, saw a break in his packed schedule, grabbed his skis and dashed off to Mt. Baldy to enjoy the fantastic new snow left by a recent storm. A former ski instructor, he was carving a fine line, lost in the rhythmic pleasure of crisp turns when, out of the corner of his eye, he saw a young snowboarder barreling toward him from above. Wirga swerved to avoid the imminent collision, caught an edge and slammed to the