Synoptic Conditions Associated with Impactful Tropical Easterly Waves

Tropical easterly waves (TEWs) drive impacts throughout and beyond the tropics. In the tropics, these typically convectively coupled waves enhance precipitation which can lead to flooding. Meanwhile, TEWs that develop into tropical cyclones (TCs) extend impacts into the subtropics and midlatitudes in the form of rain, wind, and storm surge. However, our ability to forecast these systems and their impacts is hindered by limited observations in the tropics and poor model representation. Using a global database of over 35,000 TEW tracks, with TEWs tracked independently at 850 and 700 hPa, composites of the synoptic scale environment surrounding pre-TC TEWs and TEWs associated with high amounts of precipitation will be compared to the general population of all TEWs. Variables of interest include geopotential height, relative humidity, wind, and vertical velocity. Initial work comparing sea level pressure around approximately vertically stacked TEWs against all TEWs suggest that structural differences exist, even for this broad category that includes ~22% of track points. Basin-specific composites will be created to provide additional insight into the varying processes that may contribute to TEW-related impacts in different parts of the world. By better understanding the synoptic conditions associated with impactful TEWs, it may be possible to improve forecasts of extreme rainfall and tropical cyclogenesis.