The Answer In Examples: The Making of 40 Photographs, Ansel Adams describes the location for "Clearing Winter Storm, Yosemite National Park" pretty sparingly. But Glenn Crosby, curator of the Ansel Adams Gallery, was able to find enough clues to pinpoint the spot. "The location is Discovery View, which is easily accessible and one of the best places to see the valley."
The Hike Discovery View is a small pull-off on CA 41 in the west end of the valley, 1.5 miles up the hill from the Bridalveil Falls parking lot. It's also the starting point for the stout but epically scenic Pohono Trail, which leads to a series of overlooks—Stanford, Crocker, and Dewey Points—over a stretch of 5.5 miles.