Pyrocumulonimbus clouds produced by the Cameron Peak Fire in Colorado

September 6th, 2020 |

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm), GOES-17 Shortwave Infrared (3.9 µm), Fire Temperature Red-Green-Blue (RGB) + GLM Flash Extent Density (FED) and “Clean” Infrared Window (10.35 µm) images (above) showed 2 distinct pulses of pyrocumulonimbus (pyroCb) cloud emanating from the Cameron Peak Fire in north-central Colorado on 06 September 2020. The coldest cloud-top infrared brightness temperatures were -52.4ºC. Smoke was occasionally restricting the surface visibility to 2 miles at Boulder (KBJC) and 2.5 miles at Fort Collins (KFNL).

This fire also produced a brief pyroCb cloud on the previous day (below), as shown by a single blue (-40ºC) pixel on the 10.35 µm image at 2301 UTC — however, since no Mesoscale Sector was positioned over the area, the fire was only sampled by 5-minute CONUS Sector images. The presence of cloud-top infrared brightness temperatures of -40ºC and colder assures heterogeneous nucleation of all supercooled water droplets to form ice crystals, thereby meeting the criteria of a pyroCb.

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

===== 07 September Update =====

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) images, with plots of METAR surface reports [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) images, with plots of METAR surface reports [click to enlarge]

As the fire continued burning into the nighttime hours, Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) images (above) displayed the fire around 0916 UTC or 2:16 am PDT on 07 September. Reflected illumination from the Moon — in the Waning Gibbous phase, at 76% of Full — allowed some of the eastward-drifting smoke to be seen.

A toggle between Shortwave Infrared images from Suomi NPP VIIRS (3.74 µm) and GOES-16 ABI (3.9 µm) is shown below — the shape of the Cameron Peak Fire thermal anomaly as well as locations of ongoing hot fires along its perimeter were more accurately seen in the 375-m resolution VIIRS image, compared to the 2-km resolution (at satellite sub-point) ABI image. The 2 images are time-matched to correspond to the 0922 UTC time of the Suomi NPP satellite’s overpass.

Shortwave Infrared images from Suomi NPP (3.74 µm) and GOES-16 (3.9 µm), with plots of METAR surface reports [click to enlarge]

Shortwave Infrared images from Suomi NPP (3.74 µm) and GOES-16 (3.9 µm), with plots of METAR surface reports [click to enlarge]