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Severe thunderstorms in the Southern Plains (with examples of overshooting tops with “warm trench” signatures)

By Scott Bachmeier •

GOES-16 “Clean” Infrared Window (10.3 µm) images, with time-matched SPC Storm Reports plotted in cyan [click to play animated GIF | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images with time-matched (+/- 3 minutes) plots of SPC Storm Reports (above) showed thunderstorms that produced hail as large as 4.50 inches in diameter, damaging winds to 71 mph and a tornado across parts of New Mexico, Texas and Oklahoma from the late afternoon into the subsequent nighttime hours on 11 June 2023.

In a closer look at 1-minute GOES-16 Infrared images over the Dallas-Fort Worth, Texas area (rawinsonde site KFWD) from 0000-0200 UTC on 12 June (below), several overshooting top pulses became surrounded by brief “warm trench” signatures — a likely indication of compensating subsidence around the periphery of these vigorous updrafts as they rapidly ascended past the local equilibrium level and/or tropopause. The coldest overshooting top exhibited an infrared brightness temperature of -87.6ºC at 0115 UTC.

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play animated GIF | MP4]

Comparisons of GOES-16 Infrared image, CLAVR-x Cloud Top Height and Operational Cloud Top Height for overshooting tops with surrounding “warm trench” signatures in Tarrant County and Denton County at 0106 UTC, 0116 UTC and 0121 UTC are shown below —  note how the full-resolution (nominal 2-km) CLAVR-x Cloud Top Height products (created at CIMSS) more accurately depicted the overshooting top and surrounding warm trench features, which were not as apparent in the 10-km resolution Operational Cloud Top Height products that are currently distributed to AWIPS users.

GOES-16 “Clean” Infrared Window (10.3 µm), CLAVR-x Cloud Top Height and Operational Cloud Top Height at 0106 UTC [click to enlarge]

GOES-16 “Clean” Infrared Window (10.3 µm), CLAVR-x Cloud Top Height and Operational Cloud Top Height at 0116 UTC [click to enlarge]_

GOES-16 “Clean” Infrared Window (10.3 µm), CLAVR-x Cloud Top Height and Operational Cloud Top Height at 0121 UTC [click to enlarge]

When comparing cursor-sampled values of Cloud Top Height for the coldest portion of overshooting tops in Tarrant and Denton County (below), the CLAVR-x values were always significantly higher (14.9 kft to 16.8 kft higher) — since the CLAVR-x higher spatial resolution more accurately depicted the size and location of the overshooting tops (as seen in the Infrared images).

Cursor-sampled values of GOES-16 Infrared (10.3 µm) brightness temperature, CLAVR-x Cloud Top Height and Operational Cloud Top Height for an overshooting top over Tarrant County at 0106 UTC [click to enlarge]

Cursor-sampled values of GOES-16 Infrared (10.3 µm) brightness temperature, CLAVR-x Cloud Top Height and Operational Cloud Top Height for an overshooting top over Tarrant County at 0116 UTC [click to enlarge]

Cursor-sampled values of GOES-16 Infrared (10.3 µm) brightness temperature, CLAVR-x Cloud Top Height and Operational Cloud Top Height for an overshooting top over Denton County at 0116 UTC [click to enlarge]

Cursor-sampled values of GOES-16 Infrared (10.3 µm) brightness temperature, CLAVR-x Cloud Top Height and Operational Cloud Top Height for an overshooting top over Tarrant County at 0121 UTC [click to enlarge]

However, cursor-sampled Cloud Top Height values within the corresponding warm trench features were generally similar (below), although the CLAVR-x values were usually several hundred feet lower than the Operational values.

Cursor-sampled values of GOES-16 Infrared (10.3 µm) brightness temperature, CLAVR-x Cloud Top Height and Operational Cloud Top Height for a warm trench feature over Tarrant County at 0106 UTC [click to enlarge]

Cursor-sampled values of GOES-16 Infrared (10.3 µm) brightness temperature, CLAVR-x Cloud Top Height and Operational Cloud Top Height for a warm trench feature over Tarrant County at 0116 UTC [click to enlarge]

Cursor-sampled values of GOES-16 Infrared (10.3 µm) brightness temperature, CLAVR-x Cloud Top Height and Operational Cloud Top Height for a warm trench feature over Denton County at 0116 UTC [click to enlarge]

Cursor-sampled values of GOES-16 Infrared (10.3 µm) brightness temperature, CLAVR-x Cloud Top Height and Operational Cloud Top Height for a warm trench feature over Tarrant County at 0121 UTC [click to enlarge]

Cursor-sampled values of GOES-16 Infrared (10.3 µm) brightness temperature, CLAVR-x Cloud Top Height and Operational Cloud Top Height for a warm trench feature over Denton County at 0121 UTC [click to enlarge]

The largest CLAVR-x Cloud Top Height difference between an overshooting top and its surrounding warm trench was 19,431 feet (over Tarrant County at 0116 UTC, shown below) — the corresponding lower spatial resolution Operational Cloud Top Height difference was only 2973 feet!

Cursor-sampled values of Cloud Top Height for the storm over Tarrant County at 0116 UTC [click to enlarge]

Categories: CLAVR-x, GOES-16, Severe convection