A Tale of Two Rapidly Intensifying Supertyphoons Hagibis (2019) and Haiyan (2013)

Devastating Japan in October 2019, Supertyphoon (STY) Hagibis was an important typhoon in the history of the Pacific. A striking feature of Hagibis was its explosive rapid intensification (RI). In 24 h, Hagibis intensified by 100 knots (kt; 1 kt approximate to 0.51 m s(-1)), making it one of the fastest-intensifying typhoons ever observed. After RI, Hagibis's intensification stalled. Using the current typhoon intensity record holder, i.e., STY Haiyan (2013), as a benchmark, this work explores the intensity evolution differences of these two high-impact STYs. We found that the extremely high prestorm sea surface temperature reaching 30.5 degrees C, deep/warm prestorm ocean heat content reaching 160 kJ cm(-2), fast forward storm motion of similar to 8 m s(-1), small during-storm ocean cooling effect of similar to 0.5 degrees C, significant thunderstorm activity at its center, and rapid eyewall contraction were all important contributors to Hagibis's impressive intensification. There was 36% more air-sea flux for Hagibis's RI than for Haiyan's. After its spectacular RI, Hagibis's intensification stopped, despite favorable environments. Haiyan, by contrast, continued to intensify, reaching its record-breaking intensity of 170 kt. A key finding here is the multiple pathways that storm size affected the intensity evolution for both typhoons. After RI, Hagibis experienced a major size expansion, becoming the largest typhoon on record in the Pacific. This size enlargement, combined with a reduction in storm translational speed, induced stronger ocean cooling that reduced ocean flux and hindered intensification. The large storm size also contributed to slower eyewall replacement cycles (ERCs), which prolonged the negative impact of the ERC on intensification.

Automated summary

In October 2019, Supertyphoon Hagibis devastated Japan and was an important typhoon in Pacific history. The rapid intensification and various factors such as sea temperature, ocean heat content, storm motion, and thunderstorm activity contributed to Hagibis's impressive strength evolution. Despite favorable conditions, Hagibis's intensification stalled after a significant size expansion, contrasting Haiyan which continued to intensify and reach record-breaking intensity.