Genesis and rapid weakening of tropical cyclone Lehar (2013)

Tropical cyclogenesis and rapid weakening are subjects of considerable interest in the literature. This paper addresses the genesis and rapid weakening of a North Indian Ocean tropical cyclone Lehar (November 23-28, 2013). High-resolution analysis has been created by assimilating GPSRO observations using WRF and 3DVAR assimilation techniques. The parent disturbance of tropical cyclone Lehar is traced back using a moisture variable, and it is found to be originating from a westward-moving disturbance. The pathway of genesis is found to be bottom-up, with the vorticity developing from below. Tropical cyclone Lehar weakened from a Category 1 cyclone on November 26, 2013. We analyzed the prospects that contributed to the abrupt drop of tropical cyclone Lehar's intensity in view of this. The analysis shows dust in the post-genesis (rapid weakening) environment of tropical cyclone Lehar. The analysis of total precipitable water in the post-genesis environment shows that the environment is very dry (< 45 kgm(-2)), and the spiral bands started disappearing under the influence of dry air intrusion. It has been found that the tropical cyclone Lehar is interacting with the dry air coming from the northern part of the Indian region during the post-genesis (rapid weakening) evolution, and the cyclone started weakening rapidly. The dry air advection from the north of the storm is a primary contributor to the weakening and high deep layer shear in the weakening environment.

Automated summary

This paper investigates the genesis and rapid weakening of North Indian Ocean tropical cyclone Lehar in November 2013, finding that the intrusion of dry air from the north was the primary factor leading to its rapid weakening.