A convective climatology of storms over the Green River watershed

The purpose of this study was to construct a warm season (spring-summer) convective climatology for the Green River watershed in central-western Kentucky during 1979-2009. This region is primarily utilized for agriculture, which raises concerns for water quality as pollutants (e.g., fertilizers) are transported through the watershed. This climatology was derived from daily precipitation reports from National Weather Service Cooperative weather stations. Surface METAR observations, along with the Daily Weather Maps archive from the National Centers for Environmental Prediction and radiosonde data were used to classify five types of precipitation days based on atmospheric circulation: synoptic; frontal; wraparound; tropical; ‘other'. Our study shows that there was at least one precipitation day observed within the watershed during 66% of the study period. However, when examining the spatial distribution of the total number of precipitation days for each individual station, the totals ranged from 19-31%. For the convective classifications, synoptic events were the most frequent (i.e., 31%), followed by ‘other' events (i.e., 17%). Synoptic and ‘other' events were most frequent during the spring and summer seasons, respectively. Since 'other' events exhibited a summer preference, these events were sub-classified by air mass types and proximity to surface frontal boundaries to determine whether these storm types initiated under synoptically benign conditions. For this classification, 84% occurred under these conditions, of which moist tropical air masses were dominant (72%) during that time. Future studies will focus on relating precipitation totals and intensities with each convective classification, and streamflow characteristics within the watershed.