In this training session recorded in November 2019, Dr Kevin Tory (Bureau of Meteorology) introduces a tool that has been developed to aid in the forecasting of fire-generated thunderstorms or pyrocumulonimbus (pyroCb). The tool is built around a concept termed the PyroCb Firepower Threshold (PFT), which seeks to identify the minimum firepower required to generate pyroCb for a given atmospheric environment. The video includes a presentation that introduces the PFT, explains how it works and gives examples of PFT useage. It provides valuable insight into plume dynamics, and a deeper understanding of the types of environments that support or suppress pyroCb formation. The video also includes instructions on how to calculate the PFT manually from atmospheric soundings on a thermodynamic diagram.
Pyrocumulonimbus (pyroCb) formation has much in common with conventional thunderstorms. Both require warm humid air to be lifted into an unstable layer above. A sufficiently large fire provides this lift and it boosts the temperature and humidity of the lifted air. While meteorologists have developed great skill in forecasting conventional thunderstorms, pyroCb prediction remains a substantial challenge, because anticipating the temperature and humidity boost and lift for a given fire is very difficult. The PFT offers a method to diagnose the minimum firepower required for pyroCb development, which can be presented as forecast maps to help forecasters identify how the atmospheric support for pyroCb formation varies in space and time.
To learn more about the research Dr Tory and his team are doing with the Bushfire and Natural Hazards CRC visit their project page.