Investigating the role of environmental humidity on the rapid intensification of Hurricane Earl (2010)

The role of environmental humidity on the rapid intensification of Hurricane Earl (2010) is investigated with the WRF model, with focus on the asymmetry of environmental humidity. The WRF simulation captures the rapid intensification of Hurricane Earl (2010) and the associated humidity distribution. Substantial free tropospheric moisture in the front quadrants of the storm limits hurricane intensification by facilitating precipitation formation in the environment, while enhanced moisture in the rear left quadrant helps intensification. Expansion of free tropospheric moisture from the hurricane inner core has no significant impact on hurricane intensity, but increases the size of the storm. Storm circulation strengthens upper tropospheric moisture gradient. The interaction between the environmental moisture and convective structure in the storm is best illustrated in the framework of translating streamlines and mixed Rossby-gravity (MRG) wave pouch method.