Climatology of snowfall-event characteristics at Denver

A climatology of snowfall-event characteristics for Denver, Colorado, was developed to help improve snow fall forecasts. A snowfall-event is a period of time during, which any type of frozen precipitation is observed at the station. A break between events occurs when 12 hours elapses with no precipitation. Hourly surface observations from 1948 to 1988 were examined for these features. In the investigation, characteristics such as diurnal oscillations in snowfall, preferred beginning/ending time of an event, and temperature and wind patterns were considered.The statistical approach used to analyze event characteristics reveals several interesting relationships. For example, the beginning time of precipitation is strongly tied to the timing of frontal passages, which are dependent on the time of day. One mechanism responsible for the diurnal periodicity in frontal passages is the temperature pattern. During the warmest part of the day in the spring and fall, cold fronts are insufficient in depth to penetrate west of the Continental Divide. At sunset, the temperature quickly cools so the front can continue its movement south.