A two-month numerical simulation using the PSU/NCAR MM5 version 3.5 modeling system was conducted over the period of February - April 2002. The simulation was aimed at studying mesoscale characteristics of low-level winds over the Tennessee valley during cold season when winds are typically strong. The MM5 was configured with a 27-km resolution coarse domain and a 9-km resolution nested domain. The coarse domain covers eastern half of the United States and the fine domain covers Tennessee and the surrounding states. There were 31-sigma layers in the vertical. The model was initialized with NCEP/Eta 00Z analysis and run for total of 61 days.

Composite three dimensional wind data from the hourly model output were analyzed to depict characteristics of air flows over complex terrain in the Tennessee valley, especially over the southern Appalachian Mountains. The 61 days of simulation were first divided into three groups based on weather types: Group-A represents days without frontal activities; Group-B represents days when cold fronts were observed in the Tennessee valley; and Group-C represents the rest. Composite hourly wind data were then created by averaging winds over the number of case days in each group. It is found by comparing results of Group-A with those of Group-B that low-level winds exhibit quite different diurnal patterns over east Tennessee and the southern Appalachian Mountains. In the absence of frontal activities, strong winds are identified east of the southern Appalachian Mountains and light winds are visible in the great valley of the Tennessee River especially at night. In the presence of the cold fronts, however, strong winds are found over Cumberland Plateau and east of the Appalachians, with wind channeling effect clearly shown north of the Great Smoky Mountain. The study demonstrates that the footprints of orographic flows over complex terrains can be used effectively for identifying wind energy resources in the region.