Abstract
Grid analysis of radar films at one hour intervals over two convective seasons was performed to assess the role of the synoptic situation and local topography on the pattern of showers in central Pennsylvania. Diurnal variations in extent and distribution of echoes are traceable to air motions that result from the nature of the local topography.
Correlations between synoptic variables and the amount and nature of showers show that surface dew-point depression is the best indicator of scope coverage as well as size and development of showers. It was also found that the superimposition of a favorable vertical motion field on a region of convective precipitation allows showers and squall lines to undergo greater development.