On 29 August 2017 two pyroCbs formed in the Oregon. GOES-15 detected the smoke plume and pyroCb cloud, as well as the fires hot spots. The first pyroCb cloud (~44º N, 121.1ºW) formed around 20:15 UTC on 29 August . The second formed shortly after around 43.8º N 121.4ºE at 0:00 UTC on 30 August. Starting at 20:00 UTC on 29 August, the animation below shows GOES-15 0.63 µm visible (left) and 3.9 µm shortwave IR (right) . In the shortwave IR images, the red pixels indicate very hot IR brightness temperatures exhibited by the fire source regions.
Usually GOES-15 10.7 μm IR channel is used to find the cloud-top IR brightness temperature. However, the resolution of this satellite did not provide a brightness temperature lower than -40ºC.
A 1-km resolution NOAA-19 AVHRR 10.8 µm Infrared Window image (below;courtesy ofRené Servranckx) revealed a minimum cloud-top IR brightness temperature of -42.7º C (green color enhancement) for the first pyroCb and -42.3º C for the second (green color enhancement) at 1:07 UTC on 30 August.