Tropical Tropopause Layer Hydration By Overshooting Deep Convection in Hurricanes

Localized severe thunderstorms embedded in hurricanes can exceed the height of the outflow cirrus shield. Gravity wave breaking at tower-top may be responsible for locally high rates of water vapor injection, both direct and due to ice sublimation, in the Tropical Tropopause Layer (TTL). We study these hydration events in a high-resolution realistic WRF simulation of 2020’s Hurricane Laura (dx=0.75 km, 100 vertical levels under 22 km) including the rapid intensification period and landfall. We show similarities between the storm top dynamics here and above midlatitude supercell thunderstorms. One way to identify these deep convective hydration events is to search for strong bursts of horizontal wind (> 40 m/s) near the tropopause. These simulated events are compared to Doppler radar observations of overshooting tops.