The Impact of Dry Air on Location and Strength of Tornado Outbreaks Associated with Land Falling Atlantic Basin Tropical Cyclones

Tropical cyclones that form in the Atlantic Basin are responsible for causing major disruptions across a wide range of industries from government policy to transportation and tourism. With the continuous growth of coastal cities continuing, there has been an increasing demand for the scientific community to accurately predict the tracks and intensities of tropical cyclones in order to mitigate disruptions and damages. Although the scientific community has made tremendous advances in forecasting the tracks of tropical cyclones, predicting intensity has proven to be incredibly challenging. What has proved to be equally as difficult is predicting tropical cyclones that are capable of producing tornado outbreaks. Tornadoes that form as a result of tropical cyclones represent a small percentage of total tornado reports and are often weaker compared to their supercell counterparts from mid latitude systems. Even though these tornadoes are not as common or as severe as supercell tornadoes that occur over the Great Plains, they are a serious threat to life and property. Recently it has been shown that dry air may be used as an indicator to pinpoint the location of tornado outbreaks which could give forecasters more lead time in alerting the public. Dry air can increase convective available potential energy (CAPE) which can lead to stronger updrafts, or it can lead to skies remaining clear so that solar radiation can heat the surface, eroding away any convective inhibition. All tropical cyclones that have made landfall between 2000 and 2014, regardless of their intensity, that produced at least six tornadoes will be analyzed to determine any distinguishable patterns between dry air intrusions as well as the size and location of the tornado outbreaks. Dry air intrusions will be easily visible by locating steep gradients in relative humidity. Images of relative humidity will be created using the Earth System Research Laboratory (ESRL) Daily Mean Composite page for 700, 500, 400, and 300 mb. Atmospheric soundings will also be used to analyze the environmental conditions and calculate dew point depression values before and after the tornado outbreaks to determine how strong the dry air intrusion was and what affects the dry air had on the environment.