Monday will be when the storm ramps up. The southwest wind direction will bring the steadiest snow and deepest accumulations (3-6+ inches) to the southern mountains while showers will push into the central and northern mountains with a dusting to 4+ inches in those areas.
Monday evening is when the snowfall will really get going. The strongest energy will enter Colorado at this time, and the jet stream will be overhead, which will create narrow bands of intense snow.
The forecast radar shows how the snow will ramp up and behave later Monday into Monday night. This forecast radar is from the HRRR (High-Resolution Rapid Refresh) model, updates every hour, and goes out to 18 hours. It is a good tool to track incoming and ongoing storms.
Monday night will bring bands of intense snow to all mountains, and the most intense band should cross the mountains from west-to-east between about 10pm and 4am.
Tuesday morning, the deepest snow totals in the southern mountains of 6-10+ inches overnight and in the 3-8 inch range elsewhere for overnight totals. There could be a short lull in the snow on Tuesday morning as the atmosphere takes a brief break following the intense band of snow that moved through late on Monday night.
Tuesday mid-morning through Tuesday late afternoon will bring another round of snow to all mountains. The snow will end on Tuesday early evening.
Total storm snowfall is still looking healthy with 6-12 inches for most mountains and 10-20+ inches for the southern mountains. Totals will be on or above the high end if a few of the stronger bands hit a certain area, or on the low end or below if the bands miss.