Climatology of Banded Precipitation over the Continental United States

Stationary precipitation bands have the potential to cause large amounts of accumulation due to their persistence over a given location, especially when associated with high precipitation rates. However, a climatology of stationary banded events does not exist for the United States. Such a climatology could ascertain the contribution from banded convection to annual precipitation, as well as preferential locations of mesoscale banded precipitation development. This work uses image processing techniques on US national radar composites to identify banded precipitation systems by fitting ellipses to contiguous objects that exceed 20 dBZ radar reflectivity. By defining banded systems as those with a major axis exceeding 100 km and a major to minor axis ratio of 3:1, it is possible to identify and separate mesoscale banded systems. Initial results from 2011 indicate that this method is successful at determining locations of lake-effect snow development to the east of Lake Superior and Lake Erie, as well as potential orographic banded systems in central Montana and eastern Colorado. This method is then extended over multiple years of radar composite images, building a climatology of banded precipitation occurrence for the past decade.