A fast-moving weather system is expected to bring widespread rainfall to Massachusetts on Wednesday, and in some parts of the Bay State, that rain will fall as snow. Forecasters say the precipitation should arrive between about 5 p.m. and 7 p.m. in Western Massachusetts before drifting east. The eastern part of the state should see rain arrive between 7 p.m. and 10 p.m., according to the National Weather Service.