A Mesoscale Convective System (MCS) developed over eastern Nebraska early in the evening on 11 June 2018, then propagated southward across the Plains during the subsequent overnight hours. GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images with plots of SPC storm reports are shown above; a Mesoscale Sector was positioned over the region, providing images... Read More

GOES-16 “Clean” Infrared Window (10.3 µm) images, with plots of SPC storm reports [click to play MP4 animation]
A Mesoscale Convective System (MCS) developed over eastern Nebraska early in the evening on
11 June 2018, then propagated southward across the Plains during the subsequent overnight hours. GOES-16
(GOES-East) “Clean” Infrared Window (
10.3 µm) images with plots of
SPC storm reports are shown above; a Mesoscale Sector was positioned over the region, providing images at 1-minute intervals.
A closer look over Kansas using Infrared imagery from polar-orbiting satellites (below) revealed some very cold cloud-top infrared brightness temperatures, which included -87ºC on MODIS, -90ºC on VIIRS and -92ºC on AVHRR.
![POES AVHRR, Terra/Aqua MODIS and Suomi NPP VIIRS Infrared images, with plots of SPC storm reports [click to enlarge]](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/sites/5/2018/06/180612_avhrr_modis_viirs_infrared_spc_storm_reports_Plains_MCS_anim.gif)
Metop-B AVHRR, Terra/Aqua MODIS and Suomi NPP VIIRS Infrared images, with plots of SPC storm reports [click to enlarge]
The coldest air temperature on 00 UTC
rawinsonde data from Dodge City and Topeka, Kansas
(below) was -69.5ºC (at altitudes of 14.6 km/49,900 feet at Dodge City, and 17.6 km/57,700 feet at Topeka) — so in theory air parcels and cloud material within a vigorous overshooting top could have ascended a few km (or thousands of feet) beyond those altitudes to exhibit an infrared brightness temperature of -92ºC.
![Plots of rawinsonde data from Dodge City and Topeka, Kansas [click to enlarge]](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/sites/5/2018/06/180612_00UTC_KDDC_KTOP_RAOBS.GIF)
Plots of rawinsonde data from Dodge City and Topeka, Kansas [click to enlarge]
A toggle between re-mapped versions of the GOES-16 ABI and Metop-B AVHRR Infrared imagery over Kansas at the time of the very cold cloud-top infrared brightness temperature
(below) revealed 2 important points: (1) with improved spatial resolution
(1 km for AVHRR, vs 2 km *at satellite sub-point* for ABI) the instrument detectors sensed much colder temperatures (
-92.6ºC with AVHRR vs
-81.2ºC with ABI), and (2) due to
parallax. the GOES-16 image features are displaced to the northwest. In addition to the isolated cold overshooting top in south-central Kansas, note the pronounced
enhanced-V storm top signature in far northeastern Kansas.
![Comparison of GOES-16 ABI and Metop-B AVHRR Infrared images [click to enlarge]](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/sites/5/2018/06/180612_0336utc_goes16_metopb_infrared_Kansas_anim.gif)
Comparison of GOES-16 ABI and Metop-B AVHRR Infrared images [click to enlarge]
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