{"id":66588,"date":"2025-08-22T23:59:00","date_gmt":"2025-08-22T23:59:00","guid":{"rendered":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=66588"},"modified":"2025-08-24T20:10:06","modified_gmt":"2025-08-24T20:10:06","slug":"dollar-lake-fire-in-western-wyoming-produces-a-pyrocumulonimbus-cloud","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/66588","title":{"rendered":"Dollar Lake Fire in western Wyoming produces a pyrocumulonimbus cloud"},"content":{"rendered":"
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1-minute GOES-18 Clean Infrared Window (10.3 \u00b5m) images combined with the Fire Mask derived product (cluster of semi-transparent red pixels), from 1757-2235 UTC on 22 August [click to play MP4 animation]<\/p><\/div>\n

1-minute Mesoscale Domain Sector GOES-18 (GOES-West)<\/em> Clean Infrared Window (10.3 \u00b5m) images combined with the FDCA<\/strong><\/a> Fire Mask derived product (above)<\/strong><\/em> showed that the Dollar Lake Fire<\/strong><\/a> in western Wyoming produced a pyrocumulonimbus<\/strong><\/a> (pyroCb) cloud as it was experiencing very active fire behavior (growing in size from 1300 to 5000 acres) in the wake of a cold frontal passage on 22 August 2025<\/strong><\/a>. The pyroCb cloud first exhibited a cloud-top 10.3 \u00b5m infrared brightness temperature (IRBT) of -40\u00baC (denoted by darker blue pixels) — a necessary condition to be classified as a pyroCb — at 1908 UTC<\/strong><\/a>.<\/p>\n

A non-pyroCb meteorological thunderstorm also developed just north of the Dollar Lake Fire pyroCb. While no GLM<\/strong><\/a>-detected lightning activity was seen with the pyroCb, several GLM Flash Points were associated with the northern thunderstorm (however, since the Flash Points are parallax-corrected, their surface locations appeared south-southwest of the parent thunderstorm).<\/p>\n

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GOES-18 Infrared image at 2222 UTC on 22 August, with a cursor sample of the coldest pyroCb cloud-top infrared brightness temperature [click to enlarge]<\/p><\/div>\n

The coldest pyroCb cloud-top IRBT was -53.49\u00baC at 2222 UTC, about 300 mi downwind (east) of the Dollar Lake Fire, as the leading edge of the pyroCb approached the Wyoming\/South Dakota border (above)<\/strong><\/em>. On a plot of rawinsonde data from Riverton, Wyoming (below)<\/strong><\/em> the air temperature of -53.49\u00baC occurred just above the Most Unstable (MU) air parcel’s Maximum Parcel Level (EL) of ~10.2 km.<\/p>\n

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Plot of rawinsonde data from Riverton, Wyoming at 0000 UTC on 23 August [click to enlarge]<\/p><\/div>\n

The Dollar Lake Fire burned very hot, exhibiting a 3.9 \u00b5m infrared brightness temperature of 137.88\u00baC — which is the saturation temperature of the GOES-18 ABI<\/strong><\/a> Band 7 detectors — for about 3 hours, beginning at 1823 UTC (below)<\/strong><\/em>.<\/p>\n

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GOES-18 Shortwave Infrared (3.9 \u00b5m) image at 1823 UTC on 22 August, with a cursor sample of the hottest 3.9 \u00b5m brightness temperature over the Dollar Lake Fire [click to enlarge]<\/p><\/div>\n

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The Dollar Lake Fire continues to burn today, which is very evident when you look at nearby webcams. A large smoke plume is developing and forming pyrocumulus clouds. These clouds are being picked up by our radar showing the plume continuing to spread to the east. #wywx<\/a> pic.twitter.com\/CzDa9L68qU<\/a><\/p>— NWS Riverton (@NWSRiverton) August 22, 2025<\/a><\/blockquote>