Four people have died in avalanches in Colorado this month. The deaths include a man who was snowmobiling with his brother near Buffalo Pass in Jackson County. The surviving brother was found Monday near a snow cave where he took shelter. Two skiers died in slides on Sunday. A 13-year-old boy was caught in a slide in a closed area on Vail Mountain. Taft Conlin of Eagle died on a double-black-diamond run called Upper Prima Cornice.A man skiing on the Mary Jane side of Winter Park Ski Resort on Sunday was caught in a small avalanche. Christopher Norris of Evergreen died after being buried in the snow. While avalanche deaths at ski resorts are extremely rare, at least two have been reported since 2005.A fourth man died last week after being buried by an avalanche outside the boundaries of Snowmass Ski Resort. Other skiers found the man and dug him out, but he did not survive. Avalanche forecasters say a weak base layer of snow, packed with large grains of ice that aren't well connected to each other, is plaguing parts of Colorado, Utah, Montana and California and could keep avalanche risks high for the rest of the season. "This has the potential to be a pretty dangerous winter because of the foundation," Colorado Avalanche Information Center avalanche forecaster Scott Toepfer said Tuesday. "It may haunt us into the spring." The Colorado Avalanche Information Center has recorded eight avalanche deaths around the West this season, with four in Colorado, three along the Wyoming-Montana border and one in Utah. There were 25 recorded last winter and 36 the season before.