An other blizzard swept Mammoth Mountain on Wednesday, the precursor to a string of storms expected to bring up to 20 feet of fresh snow in the next 10 days, the resort says. Since Tuesday, 26 to 48 inches of fresh snow had fallen, with the deepest totals at the summit. Plows were working furiously to keep lots and streets clear. Normal resort operations could be affected as personnel struggle to deal with the snow.