Using Channel 4 (10.7 µm) Imagery To Assess Thunderstorm Severity

  Channel 4 imagery can be used as a tool for assessing the severity of thunderstorms.   This image was taken on the afternoon of 27 May 1997 at 2045 UTC just as an F5 tornado was forming near Jarrell, TX.   The annotation indicates two "enhanced-V" signatures at top of the largest thunderstorm complex, the Jarrell storm being the southernmost of the two.   Enhanced-V's are indicative of thunderstorms having very strong updrafts.   Note the colder pixels at the cusp of each "V."   Cold tops at anvil level are also considered a good indicator of intense updrafts.