He worked a number of jobs including football coach, cattle rancher, and trapper. He lived in Montana in the 1930s and wrote short stories and mysteries, some under the pseudonym of Max Montgomery. During World World War II, he served in the 10th Mountain Division as a winter warfare instructor, eventually reaching the rank of captain while in active combat duty and being wounded.
After being discharged due to his injury, he served as a forest ranger for the Forest Service in Alta, Utah starting in the autumn of 1945.
Over the next two decades he established the first avalanche research center in the Western Hemisphere at Alta, inventing many of the techniques and much of the equipment needed for avalanche forecasting and control. Atwater served as director of avalanche control during the 1960 Winter Olympics in Squaw Valley, California, successfully preventing any major avalanches during the Games despite a history of huge chairlift-destroying avalanches there.
Afterwards he helped develop the Avalauncher, a pneumatic cannon for launching avalanche control explosives, and then retired from the Forest Service in 1964. In 1966, he repeated his masterful job of avalanche control at the alpine skiing World Championships in Portillo, Chile, where the ski area had been almost completely destroyed by massive avalanches only a year earlier but successfully held the Championships unscathed.
He also served as a consultant to ski areas, mining companies, and telecommunication companies throughout the mountainous regions of North and South America.
He had three sons, James, Robert and Montgomery. In his later years, he ran a small research lab in Squaw Valley. He died of a heart attack in 1976.