On 05 September 2017 a pyroCb formed in Washington. GOES-15 detected the smoke plumes and pyroCb cloud, as well as the fires hot spot. The pyroCb cloud from the Jolly Mountain Fire (~47.4º N, 121.0ºW) formed around 1:00 UTC . Starting at 0:00 UTC on 05 September, 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 -46.4º C (green color enhancement) for the pyroCb at 2:42 UTC on 05 September.