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Spoon Fire in Arizona produces a pyrocumulonimbus cloud

By Scott Bachmeier •

GOES-18 Day Land Cloud Fire RGB (top left), Shortwave Infrared (3.9 µm, top right), “Clean” Infrared Window (10.3 µm, bottom left) and Cloud Top Temperature derived product (bottom right) [click to play animated GIF | MP4]

1-minute Mesoscale Domain Sector GOES-18 (GOES-West) Day Land Cloud Fire RGB, Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.3 µm) and Cloud Top Temperature derived product images (above) showed that the Spoon Fire in in east-central Arizona produced a pyrocumulonimbus (pyroCb) cloud late in the day on 27 July 2023. Cloud-top 10.3 µm brightness temperatures reached the -40ºC pyroCb threshold (shades of blue) at 0043 UTC — and later cooled to a minimum of -50.48ºC (with a corresponding Cloud Top Temperature of -54.11ºC) at 0057 UTC (below).

Cursor-sampled values showing a 10.3 µm brightness temperature of -50.48ºC and a corresponding Cloud Top Temperature of -54.11ºC at 0057 UTC [click to enlarge]

A plot of rawinsonde data from Flagstaff, Arizona at 0000 UTC on 28 July (below) indicated that the -50.48ºC / -54.11ºC cloud-top temperature values were close to the height of the Equilibrium Level (EL) of a Most Unstable (MU) air parcel.

Plot of rawinsonde data from Flagstaff, Arizona at 0000 UTC on 28 July [click to enlarge]

Prior to producing a pyroCb cloud, the Spoon Fire burned very hot — 3.9 µm brightness temperatures reached 137.88ºC (which is the saturation temperature of the GOES-18 ABI Band 7 detectors) shortly after 2300 UTC, and Fire Power values reached 2842.06 MW at 2334 UTC (below). The Fire Power derived product is a component of the GOES Fire Detection and Characterization Algorithm (FDCA),

GOES-18 Day Land Cloud Fire RGB (top left), Shortwave Infrared (3.9 µm, top right), “Clean” Infrared Window (10.3 µm, bottom left) and Fire Power derived product (bottom right) [click to play animated GIF | MP4]


Cursor-sampled values showing a 3.9 µm brightness temperature of 137.88ºC along with a corresponding Fire Power value of 2842.06 MW at 2334 UTC [click to enlarge]

Categories: Fire detection, GOES-18, Red-Green-Blue (RGB) images