Small-scale Variations of Heat Index and Dewpoint from Mobile Transects

In the United States, the primary public measure of human heat stress under humid conditions is the Steadman heat index. The National Weather Service (NWS) routinely refers to heat index in both forecast messaging and current weather products. Small-scale variations of temperature associated with urban environments have been reported by various researchers using in situ climatological stations, remote sensing, and mobile transects. However the local conditions of heat index resulting from variability of both temperature and humidity are less well documented. We have begun to look at such variations in the vicinity of Columbia, Missouri using vehicular transects of nearby suburban and rural landscape features such as an incised limestone valley (Hinkson Creek) and sheltered gullies of the Missouri River bluffs. Competing effects of moisture pooling under calm conditions and vegetative shading potentially produce complex changes in human comfort. Previously the urban heat island effect of Columbia was documented by Lupo et al. in the Columbia Heat Island Experiment (COHIX). The representativeness of Missouri Mesonet and NWS ASOS observing sites for reporting human heat stress risks in the area are considered, as well as such microscale anthropogenic impacts as moisture flux from municipal waste management facilities.