GOES-16 (GOES-East) “Red” Visible ( 0.64 µm ), Shortwave Infrared ( 3.9 µm ) and “Clean” Infrared Window (10.35 µm) imagesshowed the formation of a pyrocumulonimbus (pyroCb) cloud over far southeastern Bolivia on 18 August 2019. The small anvil cloud briefly surpassed the -40ºC pyroCb threshold from 1800-1820 UTC, attaining a minimum cloud-top infrared brightness temperature of -45.2ºC along the Bolivia/Paraguay border at 1800 UTC . This pyroCb formed over the hottest southern portion of an elongated fire line, as seen in the Shortwave Infrared imagery.

A 1.5-day animation of GOES-16 Shortwave Infrared images (from 12 UTC on 17 August to 2350 UTC on 18 August) revealed the rapid southeastward run of the fire to the Bolivia/Paraguay border on 17 August, followed by the eastward expansion of the fire line on 18 August (below).

A toggle between Suomi NPP VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images as viewed using RealEarth showed the large and dense smoke plume streaming southeastward, with the small pyroCb along the Bolivia/Paraguay border at 1745 UTC — the brighter white tops of the pyrocumulus and pyrocumulonimbus clouds reached higher altitudes than the tan-colored smoke plume. The coldest cloud-top infrared brightness temperature was about -55ºC (orange enhancement), which corresponded to an altitude around 9 km according to rawinsonde data from Corumbá, Bolivia.

Looking more closely at yesterday’s smoke over South America, the aerosol index from #NOAA20 #OMPS was in double digits! Values on the right refer to the UTC of the measurements. pic.twitter.com/3XBqoEVs4M — Colin Seftor (@colin_seftor) August 19, 2019

Strong northerly to northwesterly surface winds were blowing across the region, in advance of an approaching cold front (surface analyses) — at Robore, Bolivia (located just north-northwest of the fires), winds were gusting to 25-28 knots during much of the day (below).

This is likely the second confirmed case of a South American pyroCb (the first being on 29 January 2018 ) — in addition, it’s the second pyroCb documented in the tropics and the first pyroCb documented during a winter season. Thanks to Mike Fromm (NRL) for bringing this case to our attention!

===== 25 August Update =====

GOES-16 Visible, Shortwave Infrared and “Clean” Infrared Window imagesshowed that another pyroCb developed from that same general fire complex, southwest of Robore, Bolivia (SLRB), on 25 August.

A toggle between Suomi NPP and NOAA-20 VIIRS True Color RGB and Infrared Window images as viewed using RealEarth (below) showed the large and dense smoke plume streaming southeastward, with the small pyroCb just north of the Bolivia/Paraguay border — the brighter white tops of the pyrocumulus and pyrocumulonimbus clouds reached higher altitudes than the tan-colored smoke-rich clouds at lower altitudes.