(Seattle, WA)  --  Strong plumes of moisture will bring heavy rain and snow to the northwest over the next few days. Called atmospheric rivers, the Weather Prediction Center warned residents especially in the Pacific Northwest and the Rockies of "hazardous to even impossible travel conditions in these impacted areas." More than half a dozen states in the west are now under some kind of winter weather alert as of this past weekend as the atmospheric rivers spread eastward from Washington and Oregon to Colorado and Wyoming.