As also discussed in this blog post, large hail injured as many as 90 people at a Red Rocks outdoor concert in Colorado just after local sunset on 21 June 2023. 1-minute Mesoscale Domain Sector “Clean” Infrared Window (10.3 µm) images (with/without an overlay of GLM Flash Extent Density) from GOES-16 (GOES-East) (above) and GOES-18 (GOES-West) (below) showed the east-northeastward motion of the parent thunderstorm, and the resultant path of damaging wind and large hail reports. Red Rocks Park is located near the center of the GOES-16/GOES-18 images.

Pulses of overshooting tops exhibited infrared brightness temperatures as cold as -72ºC at 0317 UTC (below) — which was about 9 minutes prior to the Local Storm Report of 2-inch diameter hail at Red Rocks — and that cold overshooting top occurred during a brief lightning jump (from 0311-0318 UTC), as indicated by GLM Flash Extent Density. Note the differences in parallax offset between the 2 satellites — a 50,000-ft cloud top feature over central Colorado would be displaced about 22 km (13.7 miles) to the northwest of its actual surface location in GOES-16 imagery, but displaced about 23 km (14.3 miles) to the northeast of is actual surface location in GOES-18 imagery. Parallax correction would therefore have displayed the cold overshooting top closer to the location of the 1.75-inch diameter hail report.

The CIMSS-produced full resolution (nominal 2 km) CLAVR-x Cloud Top Height of the coldest overshooting top was around 56,000 ft (below).

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Orbits from NOAA-20 (link, from this site) show a NOAA-20 overpass over Tropical Storm Bret at around 1700 UTC on 21 June 2023. Data from NOAA-20 were available at this site by 1730 UTC, and downloading files from the VIIRS-I1-SDR and VIIRS-IMG-GEO directories (as discussed in this blog post), and running a simple Polar2Grid (software downloadable here) command yields the full-resolution image above. For ascending (daytime!) passes, then, this could be done within 45 minutes. This particular image was posted on the blog by about 1840 UTC.

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Of course, you might not want all the imagery outside the Tropical Cyclone! Polar2Grid allows for simple definitions of grids (via the p2g_grid_helper shell script: ./p2g_grid_helper.sh GridName -52.0 13.0 375 -375 1440 1440 > $POLAR2GRID_HOME/FileName.yaml). An I01 visible image (0.64 µm) centered near Bret with the defined grid in the command above is shown below.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images (above) showed Atlantic Tropical Depression Three as it intensified to become Tropical Storm Bret at 2100 UTC on 19 June 2023. Overshooting tops exhibited infrared brightness temperature values as cold as -79ºC.

Bret was in a favorable environment for continued intensification, as shown by low values of deep-layer wind shear from the CIMSS Tropical Cyclones site (below) — and the storm was moving over relatively warm water (Sea Surface Temperature).

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GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) + Fire Power (a component of the GOES Fire Detection and Characterization Algorithm FDCA), Shortwave Infrared (3.9 µm), Day Land Cloud Fire RGB and Fire Temperature RGB images (above) showed thermal signatures and pyrocumulus pulses associated with the Pulp Road Fire in far southeastern North Carolina on 16 June 2023. Beginning at 1646 UTC, the fire occasionally exhibited 3.9 µm brightness temperatures of 137.71ºC (the saturation temperature of the GOES-16 ABI Band 7 detectors) — and Fire Power values exceeded 2300 MW at times. The fire rapidly grew in size from 2,500 acres at 1300 UTC on 16 June to 11,500 acres at 0000 UTC on 17 June.

A toggle between VIIRS Infrared Window (11.45 µm), Shortwave Infrared (3.74 µm), True Color RGB and False Color RGB images from Suomi-NPP (valid at 1747 UTC) and NOAA-20 (valid at 1819 UTC) (below) revealed that the fire produced a pyrocumulonimbus (pyroCb) cloud, which exhibited anvil-top 11.45 µm brightness temperature values of -40ºC and colder (shades of blue). Data used to create the VIIRS imagery were downloaded and processed by the SSEC/CIMSS Direct Broadcast ground station.

To the best of our knowledge, this is the first documented case of a pyroCb in the State of North Carolina.

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