Climatology of Lake-Effect Clouds over the Great Lakes

Fourteen years (1995/96 – 2008/09) of cold season (October-March) 1-km resolution GOES visible satellite images were obtained and have been examined to enhance the climatological understanding of lake-effect events in the Great Lakes region. Through expert analysis, clouds were identified over each of the Great Lakes and classified into lake-effect and non-lake-effect. Clouds that were determined to be lake-effect in nature were classified into one of the following categories: Wind Parallel Bands (WPB), Shore Parallel Bands (SPB), Mesoscale Vortices (MSV), Fog, or Unclear lake-effect. In addition, separate from the cloud classifications, lake-to-lake cloud bands extending across multiple lakes were recorded. Frequencies of lake-effect cloud types were determined for the Great Lakes region and each individul Great Lake. WPBs were found to be the most frequent lake-effect organization, while MSVs and Fog were the least observed. These results support the findings of past studies in terms of trends; however, lake-effect cloud frequency was found to be larger than previously reported. This may be partially explained by the higher spatial and temporal image resolution used in the current study relative to those used in past studies. Comparisons with previous studies, as well as an examination of the intra-annual inter-annual lake-effect cloud frequency will be presented.