Pyrocumulonimbus cloud in Canada’s Northwest Territories

June 24th, 2022 |

GOES-18 “Red” Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, center) and “Clean” Infrared Window (10.35 µm, bottom) images, which include hourly plots of surface reports [click to play animated GIF | MP4]

GOES-18  images in this blog post are preliminary and non-operational

GOES-18 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed the formation of a small pyrocumulonimbus (pyroCb) cloud — generated by a wildfire that was burning near the northwest coast of Great Slave Lake in the Northwest Territories of Canada — on 24 June 2022. The pyroCB cloud then drifted southeastward across the lake, toward Resolute Bay (CYFR). Incidentally, this was Canada’s first documented pyroCb of the 2022 wildfire season.

Suomi-NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images valid at 1930 UTC, with plots of surface reports [click to enlarge]

Suomi-NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images valid at 1930 UTC (above) showed the pyroCb shortly after it formed (when it exhibited a minimum cloud-top 11.45 µm infrared brightness temperature of -49C, lighter shades of red) — and Suomi-NPP VIIRS images valid at 1930 UTC (below) displayed the pyroCb over Great Slave Lake at 2110 UTC (when it exhibited a minimum cloud-top 11.45 µm infrared brightness temperature of -54C, darker shades of violet).

Suomi-NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images valid at 2110 UTC, with plots of surface reports [click to enlarge

2 pyrocumulonimbus clouds produced by the Calf Canyon/Hermit’s Peak Fire in New Mexico

June 14th, 2022 |

GOES-17 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Infrared Window (10.35 µm, bottom left) and Cloud Top Temperature derived product (bottom right) [click to play animated GIF | MP4]

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.35 µm) and Cloud Top Temperature derived product images (above) showed that the Calf Canyon Fire/Hermits Peak Fire in northeastern New Mexico produced a pair of pyrocumulonimbus (pyroCb) clouds on 14 June 2022. Extreme fire behavior was aided by surface wind gusts as high as 60 mph and very dry air within the boundary layer. Ths large fire burned very hot, with 3.9 µm Shortwave Infrared brightness temperatures reaching 138.71ºC — the saturation temperature of ABI Band 7 detectors — for extended periods of time. Coldest 10.35 µm cloud-top brightness temperatures exhibited by the pyroCb cloud were around -46ºC (lighter blue enhancement), with the Cloud Top Temperature product showing values as cold as -61ºC (green pixels). This was the 4th day of pyroCb production by this fire — following previous events on 14 May, 10 May and 01 May.

In a toggle between Suomi-NPP VIIRS True Color RGB and False Color RGB images valid at 2051 UTC (below), the True Color image highlighted the smoke plume while the False Color image showed the active fires (brighter shades of pink) along with the size of the burn scar (shades of brown).

Suomi-NPP VIIRS True Color RGB and False Color RGB images valid at 2051 UTC [click to enlarge]

Pyrocumulonimbus clouds in Alaska

June 11th, 2022 |

Sequence of Suomi-NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images at 2149 UTC and 2332 UTC [click to enlarge]

A sequence of Suomi-NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images at 2149 UTC and 2332 UTC (above) showed “before” and “after” views of a  pyrocumulonimbus (pyroCb) cloud that developed south of McGrath, Alaska late in the day on 11 June 2022. The coldest cloud-top infrared brightness temperature of the pyroCb cloud on the 2332 image was -48C.

A couple of hours later, preliminary / non-operational GOES-18 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.35 µm) images (below) showed that the Little Hog Butte Fire — located southwest of Lake Minchumina (PAMH) — produced a larger and more long-lived pyroCb cloud, which then drifted east-northeastward from the fire source region. The coldest cloud-top infrared brightness temperature of that pyroCb cloud was around -48C. Smoke from this fire was reducing the surface visibility to 2 miles at times at Lake Minchumina. Particularly noteworthy was the fact that this was the first documented pyroCb over Alaska in 2 years.

GOES-18 “Red” Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, center) and “Clean” Infrared Window (10.35 µm, bottom) images, with hourly plots of surface reports [click to play animated GIF | MP4]

Another pyrocumulonimbus cloud spawned by the Calf Canyon Fire in New Mexico

May 14th, 2022 |

GOES-18 “Red” Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, center) and “Clean” Infrared Window (10.3 µm, bottom) images, with hourly plots of surface reports [click to play animated GIF | MP4]

Preliminary / non-operational GOES-18 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed that the Calf Canyon Fire/Hermits Peak Fire in northern New Mexico produced another another pyrocumulonimbus (pyroCb) cloud on 14 May 2022 — following 2 previous pyroCb events on 10 May and 01 May. This particular pyroCb first exhibited cloud-top infrared brightness temperature (IR BT) values of -40C and colder (shades of blue in the bottom panel) at 2211 UTC, and later attained IR BTs in the -50s C (shades of red in the bottom panel).

A comparison of Suomi-NPP VIIRS True Color RGB, False Color RGB, Infrared Window and Shortwave Infrared images valid at 2032 UTC is shown below. These VIIRS images were acquired and processed using the Direct Broadcast ground station at SSEC/CIMSS.

Suomi-NPP VIIRS True Color RGB, False Color RGB, Infrared Window (11.45 µm) and Shortwave Infrared (3.74 µm) images [click to enlarge]