@article {bnh-8134, title = {The real-time trial of the Pyrocumulonimbus Firepower Threshold}, number = {694}, year = {2020}, month = {03/2020}, institution = {Bushfire and Natural Hazards CRC}, address = {MELBOURNE}, abstract = {

This document reviews the real-time trial of the Pyrocumulonimbus Firepower Threshold (PFT) diagnostic during the 2019/2020 southern Australian fire season. The PFT was developed with support from the Bushfire and Natural Hazards Cooperative Research Centre, through the {\textquotedblleft}Improved prediction of severe weather to reduce community impact{\textquotedblright} project. While this report was primarily prepared to meet project requirements, it contains useful information and insight into the PFT and deep moist pyro-convection prediction more generally, that should be of value to fire-weather forecasters, fire-behaviour analysts and their parent agencies.

The report introduces the PFT in Section 1 and shows examples of the forecast products from the 2019/2020 season in Section 2. Throughout the trial users provided feedback that ranged from technical issues to broader forecasting challenges. This feedback identified confusion surrounding the definition of pyroCb (Section 3), and difficulties in forecasting this not-well-defined and not- well-understood phenomenon (Section 4). Many examples are presented in Section 5 to illustrate some of the more pertinent issues that arose throughout the trial. These include the limitations of using parcel theory to predict moist- plume growth, and the need to include more factors in lightning prediction. Examples are also provided that illustrate the limitations of various PFT products. The application of the PFT to climate studies is discussed in Section 6, where the minimising of false positives is of higher importance than for forecasting applications where expert users can separate real from false threats. Methods to address two of the issues raised in the report were developed with support from the Earth System and Climate Change Hub of the Australian Government{\textquoteright}s National Environmental Science Programme. These are the reduction of false positives caused by unstable conditions during cold- outbreaks, and a procedure to bypass the parcel-theory assumption (Section 7). The report is summarized in Section 8, which includes a set of dot points that highlight areas for future investigation and lessons learned.

}, keywords = {extreme, firepower, PFT, pyrocumulonimbus, real-time, threshold, trial}, issn = {694}, author = {KJ Tory} }