1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) include an overlay of GLM Flash Extent Density — which showed the severe thunderstorm that produced an EF3-rated tornado in Virginia Beach, Virginia on 30 April 2023. With that particular storm a lightning jump began around 2135 UTC and peaked at 2142 UTC, and the coldest cloud-top infrared brightness temperature of -55.58ºC occurred at 2145 UTC — both during the minutes leading up to the tornado, which formed at 2148 UTC.The coldest Cloud Top Temperature derived product (which also occurred at 2145 UTC) was about 0.9ºC colder, at -56.49ºC.

A plot of rawinsonde data (source) from Wallops, Virginia at 0000 UTC on 01 May (below) indicated that the -56.49ºC Cloud Top Temperature value roughly corresponded to a Most Unstable air parcel Equilibrium Level (MU EL) overshoot of about 1 km.

A toggle between GOES-16 Visible, Infrared and GLM Flash Extent Density images at 2147 UTC (above) showed that the thunderstorm responsible for the 2148-2153 UTC tornado — whose SW-to-NE track was from Lynnhaven to Cape Henry — was apparently located just offshore (centered over the Chesapeake Bay Bridge Tunnel). However, one must take parallax into account — which in this case was a northward displacement of around 14 km or 8.7 miles (below).

A blog post discussing the use of Polar Hyperspectral Sounding data in a numerical model simulation for this storm is available here.

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Overlapping 1-minute Mesoscale Domain Sectors provided GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images at 30-second intervals (above), which included plots of time-matched (+/- 3 minutes) SPC Storm Reports — showing thunderstorms that produced a few tornadoes, hail as large as 1.75 inches in diameter and wind gusts to 76 mph across parts of the Florida Panhandle (and adjacent far southwestern Georgia) on 27 April 2023. Pulsing overshooting tops exhibited infrared brightness temperatures as cold as -82ºC (violet pixels).

The coldest overshooting tops were associated with experimental CLAVR-x Cloud Top Height of 16.64 km (54593 ft), vs. 47866 ft (14.59 km) with the Operational CONUS sector Cloud Top Height product (below). The CLAVR-x derived GOES cloud products produced at CIMSS are at full 2 km spatial resolution — in contrast to some of the Operational cloud products, including Cloud Top Height, which are still disseminated at reduced resolutions of 10 km over the CONUS sector (although the Cloud Top Height spatial resolution is 4 km for the Mesoscale Domain Sector).

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There are different RGBs available to monitor volcanic signatures within a cloud, and three common ones are shown above. The Dust RGB and the Ash RGB use identical channels/channel differences that are scaled differently. All three RGBs (here is the The SO₂ RGB Quick Guide) include Band 11 information; Band 11 detects radiation in the part of the electromagnetic spectrum that is sensitive to absorption by SO₂. For the Sheviluch eruption (described in blog posts here and here) that occurred just at the beginning of this animation above, the SO₂ signal — bright yellow in the SO₂ RGB — persists the longest. That, of course, will not be the case with every eruption; that’s why one must use more than one product to monitor an eruption.

Note that “Keep Out Zones” are apparent in the imagery above as regions of no data around 1440 UTC, when the Himawari-9 imager is turned off when it is pointing a little too closely towards the Sun.

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Himawari-9 imagery in this blog post are courtesy of JMA. The Full-Disk HSD data were processed into RGB images using geo2grid.

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By 14 April, much of the signal has shifted eastward out of Himawari-9’s field of view. The animation below, from GOES-18, shows the three RGBs from 0000 UTC on 14 April through 0000 UTC on 20 April. The signal of enhanced SO2 in particular has remarkable staying power.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) include plots of time-matched (+/- 3 minutes) SPC Storm Reports — which showed thunderstorms that produced hail as large as 4.50 inches in diameter and wind gusts to 63 mph across North Texas on 26 April 2023.  Cloud-top infrared brightness temperatures were as cold as -81ºC at 2328 UTC (violet pixels), and Above-Anvil Cirrus Plumes (reference | VISIT training) were evident with the 2 more dominant supercell thunderstorms.

1-minute GOES-16 Visible and Infrared images with/without an overlay of GLM Flash Extent Density (below) revealed that the easternmost supercell thunderstorm tended to exhibit a bit more lightning activity. These severe thunderstorms developed just to the north of a quasi-stationary frontal boundary that was draped across North Texas.

GOES-16 Visible and Infrared images at 0022 UTC (above) showed an Above-Anvil Cirrus Plume (AACP) particularly well — at that time there was a 20ºC infrared brightness temperature difference between the cold overshooting top (-76ºC, darker black enhancement) and the downwind AACP (-56ºC, brighter green enhancement). A warmer AACP was consistent with warming temperatures above the local tropopause, as seen in a plot of rawinsonde data (source) from Fort Worth, Texas at 0000 UTC (below).

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