Observations of a frontal–trough merger over a wildfire, Queensland, Australia

Abstract The incursion of a cold front into the subtropics may cause a pronounced airmass boundary and trigger severe storms with associated meteorological hazards. Here we present the first observations of a frontal–trough merger that impacted a wildfire in subtropical southeast Queensland, Australia. Analysis of aerological profile data and reanalysis products indicated that a nocturnal elevated mixed layer was the source of instability leading to the formation of elevated storms along a 300 km frontal–trough merger. Using mobile weather radar, we identify downbursts descending from elevated convective cells at a distance of more than 20 km from the wildfire. These caused severe surface level winds above 25 m·s −1 that resulted in a rapid increase in the local Forest Fire Danger Index to 125 (Catastrophic). Lightning from the elevated dry‐base storms resulted in new fire ignitions that led to evacuations the following day. We conclude that mobile weather radar should be considered essential for providing real‐time environmental intelligence on wildfire–atmosphere interactions to mitigate risk to lives, property, and the environment.