Explaining agricultural drought in the United States Midwest

Drought affects the livelihood of many people, and its impact on society may last for several years after the event. Droughts, however, are difficult to study because there is uncertainty when trying to define what exactly constitutes a drought. Drought has different significance depending on who or what it is affecting. Equally as challenging is identifying the onset, severity, and spatial extent of a drought. This study seeks to explore a third dilemma in drought research: what is a possible cause for drought? The focus of this study is to examine the timing of El Niño and La Niña events with short-term droughts in Minnesota, Wisconsin, Iowa, Illinois, and Indiana. When using total monthly precipitation data only for June, July, and August (months important to agriculture in the Midwest) to identify a drought, can spatially coherent drought patterns be identified during an El Niño or La Niña year?