Diagnosis of the Interaction of Recurving Tropical Cyclone Lan (2017) with the Extratropical Flow in fvGFS

In late October 2017, Tropical Cyclone (TC) Lan recurved out of the tropical West Pacific and brought damaging wind and flooding rain to Japan. During this period, the recurving TC significantly interacted with the extratropical flow, as evidenced by diabatically driven divergent outflow impinging upon the midlatitude potential vorticity waveguide. In response to the TC–extratropical flow interaction associated with TC Lan, a baroclinic Rossby wave train amplified over the North Pacific and dispersed downstream to North America, where it contributed to extreme heat and devastating wildfires in California. This presentation will examine dynamical signatures of this TC–extratropical interaction and associated Rossby wave amplification and dispersion in the fvGFS, GFDL’s experimental global nonhydrostatic numerical weather prediction model comprised of a Finite­ Volume Cubed-Sphere dynamical core and Environmental Modeling Center Global Forecast System physics.