On Developing a Drought Climatology for Delaware: Related Synoptic Patterns

Drought index (Palmer Drought Severity Index and Standardized Precipitation Index), precipitation, and stream gage data were used in the development of a drought climatology for Delaware based on the period 1948 to 2005. Twelve meteorological droughts were identified during the study period, eleven of which resulted in concurrent hydrological droughts. Analysis of drought index and precipitation data revealed that meteorological drought is, on average, more severe in northern Delaware than in coastal and southern regions of the state. Through the analysis of the 500hPa height anomalies observed during each respective drought, several synoptic patterns were found to be associated with drought occurrence in the state. Findings from the map analysis were supplemented with a pre-existing synoptic climatology for the greater Philadelphia area (and surrounding region) for the identification of specific synoptic patterns most often associated with drought onset, duration, and cessation in Delaware (and the Mid-Atlantic region).