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Wildfire in Ontario produces a large pyrocumulonimbus cloud

By Scott Bachmeier •

GOES-19 Infrared images + Fire Mask derived product [click to play MP4 animation]

10-minute Full Disk scan GOES-19 (GOES-East) Infrared images combined with the Fire Mask derived product (above) showed a wildfire in western Ontario (north of Red Lake, CYRL) that produced a large pyrocumulonimbus (pyroCb) cloud beginning at 1930 UTC — when cloud-top infrared brightness temperatures first reached -40ºC, darker shades of blue — on 10 July 2025. The wildfire was intensifying in advance of an approaching warm front (SW winds at Red Lake were gusting to 19-20 knots).

GOES-19 Infrared image at 2150 UTC on 10 July, with a cursor sample of the coldest pyroCb cloud-top infrared brightness temperature [click to enlarge]

The pyroCb — which eventually merged with other nearby meteorological thunderstorms — exhibited cloud-top infrared brightness temperatures as cold as -67.75ºC at 2150 UTC (above).

In a plot of rawinsonde data from Pickle Lake, Ontario (CYPL) at 0000 UTC on 11 July (below), the -67.75ºC cloud-top temperature corresponded to an overshoot of the Equilibrium Level (EL) / Tropopause of nearly 1 km.

Plot of rawinsonde data from Pickle Lake, Ontario at 0000 UTC on 11 July [click to enlarge]

This pyroCb cloud produced a notable amount of lightning (beginning at 1950 UTC), as seen from overlays of GOES-19 GLM Flash Extent Density and Flash Points (below).

GOES-19 Infrared images + Fire Mask derived product, with an overlay of GLM Flash Extent Density and GLM Flash Points [click to play MP4 animation]

A toggle between NOAA-21 VIIRS GeoColor RGB images (with an overlay of NOAA-21 VIIRS Fire Radiative Power) at 1755 UTC and 1943 UTC is shown below (source). The later image displayed the pyroCb cloud shortly after its formation, as it had begun drifting eastward away from the large wildfire.

NOAA-21 VIIRS GeoColor RGB images with an overlay of NOAA-21 VIIRS Fire Radiative Power, at 1755 UTC and 1943 UTC on 10 July [click to enlarge]

Categories: Fire detection, GLM, GOES-19, Lightning, NOAA-21, RealEarth, Red-Green-Blue (RGB) images, VIIRS