Cumulus flammagenitus on west coast Australia
9 October 2018 02:00–08:00 UTC
Clouds that probably developed as a consequence of convection initiated by heat from forest fires in Western Australia in October 2018 could be seen on satellite imagery.
16 January 2023
09 October 2018
By HansPeter Roesli (Switzerland)
On 9 October 2018 fires (probably controlled) burnt about 35 km inland of the coast of Western Australia and 40 km south-southeast of Perth. The Suomi-NPP VIIRS Natural Colour RGB at 375m spatial resolution at 05:16 UTC (Figure 1) showed at least one active fire (yellow arrow pointing to red dot). And it appears that more active fires were lined up in southerly direction (faint red coloured dots below the larger red dot).
A blue smoke plume extended westward from the line of fires, being driven out over the coastal waters of the southern Indian Ocean. Slightly downwind of the fires, a small cluster of cumulus clouds was present (cyan arrow), partially obscured by their own shadows. The cluster was positioned over the borderline between more elevated terrain to the east (~300m above sea level) and the coastal plain to the west.
Although the cluster was situated downwind of the active fires, it may have been formed by cumuli flammagenitus (clouds that develop as a consequence of convection initiated by heat from fires). This is corroborated by the 10-minute Himawari-8 higher-resolution VIS0.64 band image sequence between 02:00 and 08:00 UTC (Figure 2).
The evolving cluster clearly stood out in the scene between 05:00 and 06:00 UTC. It was stationary at that time and only later, after rising higher, did it join the other small cumuli that were floating south-eastward through the scene.
The Perth radiosoundings at 00:00 and 12:00 UTC (Figure 3) showed north-westerly winds above 700 hPa, while winds from the easterly sector (driving the smoke plume) prevailed below. Towards the evening, while the smoke trailed away over the coastal waters, clouds, embedded thunderstorms and showers, moved in from north.
