Ground-based radar imagery from Jamaica shows the core has continued to become better defined over the last six hours. A potentially catastrophic situation unfolding for Jamaica. #Melissa

Ugh, I just realized a typo in my original post. This should read 45 kt intensification in the previous 12 h and 55 kt in the previous 18 h. Nevertheless, extreme RI is still ongoing.

One hypothesis is that because you usually have some degree of downshear convection in all TCs, anomalous upshear convection results in a greater projection of diabatic heating onto the azimuthal mean. This can aid evacuation of mass out of the boundary layer and intensify the primary circulation.

To summarize: RI tends to occur in vortices that are anomalously tall and narrow and in TCs with anomalously deep convection in the TC inner core. We hypothesize this helps evacuate mass out of the boundary layer, leading to the inward advection of angular momentum surfaces.