Calumet, Nov. 14. - Lake Superior is being swept by a heavy storm from the north-west which threatens to bring snow. All boats have been warned to seek shelter. A dozen or more boats are known to be out on the lake, including the Lakeland, which passed Keweenaw point this morning; the revenue cutter Tuscarora and the tug Hebard, both of which are searching for wreckage along the south shore. There are also several tugs out from Port Arthur in the vicinity of Isle Royale, looking for two wrecks reported there this week, but they are in little danger, as good harbors are plentiful.