A zoomed-in image of a squall line over eastern Texas observed by VIIRS at 19:24 UTC on 25 January 2012. Colors indicate channel I05 brightness temperatures. The color scale is as follows (in decreasing temperature): yellow begins at 245 K, red begins at 237 K, magenta begins at 229 K, light blue begins at 221 K, green begins at 214 K, gray/white begins at 205 K and dark blue begins at 196 K.
The dark blue area near the center of the image represents an overshooting cloud top with brightness temperatures less than 196 K (-77 C). The nearest sounding, collected at 18:00 UTC at Lake Charles, LA, observed a minimum temperature of -74 C at 17.9 km. This overshooting top is approximately 5 km in diameter.