Flash Droughts in the Wake of Landfalling Atlantic Tropical Cyclones

A new methodology has been introduced to detect flash droughts. This method is based off a new variable created called the drought index. This index is calculated using the cumulative daily anomalies of soil moisture, precipitation, and surface temperature. The viability of this methodology is tested using confirmed flash drought case studies from previous studies. The advantage of the drought index is that it allows for the identification of the flash drought period in a more objective manner than earlier studies. While relatively uncommon, it is possible for flash droughts to develop in the environment created post-landfall of an Atlantic Tropical Cyclone (TC). The new flash drought detection method created was then used to detect flash droughts in the wake of landfalling Atlantic TCs. Of the thirty landfalling Atlantic TCs examined between 2000 and 2018, only four cases resulted in the development of a flash drought. Despite TCs causing an increase in soil moisture, the decrease in precipitation and increase in surface temperature post-landfall in these four cases resulted in the development of a flash drought. When these flash droughts did occur, it was in conjunction with an already existing large-scale drought in the vicinity of the landfall. This suggests that the flash droughts extended the reach of the large-scale droughts to the landfall region of the TC.