The temperature scale is in °C, showing the coldest areas in red color.
At 6:15 UTC the formation of the "cold-ring" starts over the border of Slovenia and Italy.
At 6:30 UTC "cold-ring" was clearly visible on the Slovenian-Italian border and was identified until 7:30 UTC remaining almost stationary over NW Slovenia. The characteristics of the cold ring and the adjacent Central Warm Spot (CWS) were for this case the following:
This cold ring identification was clear indication about the penetration of the cloud tops into the tropopause.