Case studies of one light snow event and one heavy snow and rain event that occurred during the operational demonstration of the Maintenance Decision Support System (MDSS) during the winter of 2003 in Central Iowa are presented. The synoptic situation is briefly described to give an overview of the entire weather system for each event. Several parameters from the MDSS output and the ground truth at the METAR stations will be compared at two sites, Des Moines (KDSM) and Ames (KAMW).

Standard meteorological parameters, such as air temperature, relative humidity, wind speed, and precipitation type and amount, as well as extended parameters, such as road temperature and road treatment recommendations are included in the verification. Recommended road treatments versus actual road treatments as recorded by the road maintenance personnel are compared and discussed for two highway segments. Finally lessons learned from each event are recognized and addressed.

Forecasts for all the meteorological parameters in the light snow event were reasonable. However, a sharp drop in air temperature that followed the snowfall was poorly forecast. This, in combination with the lack of a blowing/drifting snow scheme in the RWFS resulted in poor road treatment recommendations. During the heavy snow and rain event the air temperature was under forecast by both the RWFS and the National Weather Service, resulting in a misforecast of an extensive period of freezing rain during the early part of the event. The road treatment recommendations in both cases were reasonable given the forecast from the Road Weather Forecast System (RWFS).