A clash of two seasons will see an early winter blast meet record autumn warmth over the next few days -- and that meeting will lead to a robust storm system with heavy mountain snow in the West and severe storms in the South. "An active end to the (workweek) is in store for much of the country as a highly amplified upper-level trough swings eastward and triggers multitudinous weather hazards for areas west of the Mississippi River," the Weather Prediction Center said.