Abstract：Hurricane Michael was intensifying as it made landfall devastating areas of the Florida Panhandle including the small town of Mexico Beach. The structure of the hurricane is examined using radar wind data made available from aircraft reconnaissance missions. This showed a dominant warm air advection configuration (winds turning in direction in an anticyclonic fashion with height) around the core of the hurricane. Conventional radiosonde data was also used to study the warm air advection environment east of a deep layered tough system which Michael moved into and which appeared to favour such strong intensification. The structure of this deep trough is also examined and compared with a situation where Hurricane Dennis in 2005 weakened as it approached the coast in much the same region. It appears that the thermal structure of the upper trough at low to middle levels is critical to whether the hurricane intensifies or weakens with the presence of strong cold air advection associated with weakening.