Birth of a hurricane: early detection of large-scale vortex instability

Abstract

Abstract A way is substantiated for detecting new large-scale vortex instability in the tropical atmosphere. The instability may occur several hours or even several dozens of hours before the formation of a tropical depression or tropical storm. The diagnosis of instability was developed on the basis of data from idealized cloud-resolving atmospheric simulation for tropical cyclogenesis. It is suggested how the evolving instability may be traced by combining high-resolution numerical modeling and GOES Imagery. As an illustration, it is speculated and discussed that the instability may have emerged in future Hurricane Isaias (2020) when it had a status of Potential Tropical Cyclone for 36 hours before it was diagnosed as Tropical Storm.