Boston and Denver are known to be snowy cities; the annual average snowfall in Boston is 44 inches while Denver's average exceeds 57 inches. However, the seasonal timing and dynamics of their snowstorms are significantly different.
Boston, now in the midst of a crippling series of snowstorms, generally receives regular periods of snowfall during the winter months as cold fronts drop across the Great Lakes and New England; the associated center of low pressure typically moves southeastward, toward the Mid-Atlantic region, and then heads up the Eastern Seaboard, sweeping Atlantic moisture over the entrenched cold air. Depending on the intensity of that low, blizzards and coastal flooding may develop, as we have seen over the past month.
Denver, on the other hand, far from the ocean, receives most of its annual snow during the late autumn and early spring, when a gyrating jet stream pulls Gulf of Mexico moisture into the Great Plains and a potent storm system (typically moving east along the Colorado-New Mexico border) sweeps it toward the Front Range; rising with the terrain, the moisture laden air cools further, dropping its cargo of precipitation. During the winter months, when Arctic fronts drop across the High Plains, some upslope flow may develop but the air is often too dry to generate much snowfall; should the cold blast arrive from the northwest, the high wall of the Front Range wrings out most of the precipitation, sparing the urban corridor.
