Following several mild, sunny days along the Front Range, snow is expected to arrive this evening and last through much of tomorrow. It will develop along the leading edge of the latest Polar Vortex as it sinks across the Heartland, eventually bringing freezing temperatures as far south as the northern Gulf Coast.
When these domes of dense, Arctic air plunge southward, they often track east of the High Plains, guided by the topography of the Continent. On occasion, as will occur this week, they back up against the Front Range and slide southward along the mountains. In general, this pattern brings frigid air to the urban corridor but does not usually produce much snow.
On the other hand, the cold, dense air may sit in place for several days until displaced by a new Pacific Front. Unfortunately, the intense Colorado sunshine pierces the atmosphere at a low angle in mid winter and adds little warmth under such conditions.