Another view using GOES-16 “Red” Visible, Shortwave Infrared, “Clean” Infrared Window (10.3 µm) and the Cloud Top Temperature product (below) showed the pyroCb cloud as it drifted rapidly northeast over Nevada and Oregon, along with a second (albeit smaller) pyroCb cloud which developed around 0130 UTC. One standard parameter used for defining a pyroCb cloud is a minimum cloud-top longwave infrared brightness temperature of -40ºC (ensuring complete glaciation) — and in this case with 1-minute imagery, the multi-spectral Cloud Top Temperature (CTT) product (FAQ) indicated that the pyroCb cloud reached the -40ºC threshold 19 minutes earlier than the 10.3 µm infrared imagery. From that point forward, the CTT product was consistently at least 5-10ºC colder than the 10.3 µm brightness temperature; the CTT product eventually displayed a minimum value of -53.9ºC over northeastern California. Even as the 10.3 µm brightness temperature began to rapidly warm after about 0100 UTC, the CTT product continued to display values in the -45 to -50ºC range (shades of green) which allowed for unambiguous tracking of the pyroCb.In the case of the second (smaller) pyroCb cloud that formed from the Carr Fire after 0130 UTC, the 10.3 µm brightness temperature failed to reach the -40ºC threshold, while the CTT product again displayed values in the -45 to -50ºC range. The coldest CTT value of -53.9ºC (seen with the initial pyroCb) roughly corresponded to an altitude of 12.5 km or 41,000 feet according to 00 UTC rawinsonde data from Reno, Nevada (below). Strong upper-tropospheric winds of 80-90 knots rapidly transported the pyroCb anvil northeastward.