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Wildfires in British Columbia and Alberta produce numerous pyrocumulonimbus clouds

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 “Red” Visible (0.64 µm) + Fire Power derived product (bottom right), from 1750 UTC on 22 September to 0500 UTC on 23 September [click to play animated GIF | MP4]

10-minute Full Disk sector GOES-18 (GOES-West) Day Land Cloud Fire RGB, Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.3 µm) and “Red” Visible (0.64 µm) + Fire Power derived product (a component of the GOES Fire Detection and Characterization Algorithm FDCA) images (above) showed signatures of multiple wildfires across northeastern British Columbia (BC) and northwestern Alberta (AB), some of which produced numerous  pyrocumulonimbus (pyroCb) clouds late in the day on 22 September 2023. Several of these fires burned very hot, exhibiting 3.9 µm shortwave infrared brightness temperatures of 137.88ºC (the saturation temperature of GOES-18 ABI Band 7 detectors) — and for the large wildfire near Rainbow Lake AB (CWSH), Fire Power values intermittently reached the 6400-6405 MW range (which are the highest GOES Fire Power values sampled by this author for any wildfire).

True Color RGB images from the CSPP GeoSphere site (below) displayed the BC/AB pyroCb development, as well as widespread dense smoke from the many wildfires across the region.

GOES-18 True Color RGB images [click to play MP4 animation]

A longer animation of GOES-18 Infrared images covering a larger area (below) showed that while two of the largest BC fires produced 1 to 4 pyroCb clouds each — pyroCb clouds are defined as having cloud-top 10.3 µm infrared brightness temperatures of -40ºC and colder, shades of blue — one of the two largest AB fires produced an amazing string of 7 pyroCb clouds (between 2300 UTC on 22 September and 0800 UTC on 23 September). About 100 miles downstream (northeast) of that prolific pyroCb-producing AB wildfire, smoke reduced the surface visibility to 1/2 mile for several hours at Hay River (CYHY) in the Northwest Territories.

GOES-18 “Clean” Infrared Window (10.3 µm) images, from 2030 UTC on 22 September to 1000 UTC on 23 September [click to play animated GIF | MP4]

The coldest cloud-top 10.3 µm infrared brightness temperature exhibited by the largest of the AB pyroCbs was -60.6ºC — placing it at an altitude near 12 km (just below the tropopause) as seen in a plot of rawinsonde data from Fort Nelson BC (CYYE) (below).

Plot of rawinsonde data from Fort Nelson, British Columbia at 0000 UTC on 23 September [click to enlarge]

GOES-18 True Color RGB images [click to play MP4 animation]

On the following day, the leading edge of high-altitude BC/AB pyroCB smoke plumes could be seen moving southeastward across Hudson Bay in True Color RGB images from both GOES-18/GOES-West (above) and GOES-16/GOES-East (below).

GOES-16 True Color RGB images [click to play MP4 animation]

Categories: Air quality, Fire detection, GOES-16, GOES-18, Red-Green-Blue (RGB) images