Upper tropospheric conditions in relation to the cloud top features of 15 August 2010 convective storms

This study focuses on 15 August 2010, when many severe convective storms occurred over parts of central and Eastern Europe, with some of these exhibiting various interesting cloud-top characteristics observed by weather satellites. The importance of the phenomena of cold-U and cold-ring features in the infrared brightness temperature enhanced imagery stems from the fact that storms exhibiting these features are very often accompanied by severe weather. Therefore, besides the general description of the atmospheric conditions in the area, we seek possible reasons for the different cloud-top appearance of these storms from the perspective of Meteosat Second Generation and polar-orbiting weather satellites. Two main issues are discussed in this paper - the unusually warm appearance of the cloud-top of the “Prague hailstorm” and the presence of cold-ring and cold-U shaped storms in close proximity to the warmer “Prague hailstorm”. Both of these issues prove that the storm top appearance is very sensitive to the upper tropospheric and lower stratospheric conditions, with the first one strongly reflecting variations in the tropopause height due to the presence of the jet-stream over the region. The second topic addresses the strength of the storm relative upper level winds as a major discriminator between the cold-U and cold-ring storm top categories. Due to the above mentioned facts, 15 August 2010 was selected as one of the prime cases of interest for the Convection Working Group.

► Different appearance of the storm-tops from the IR-BT channel perspective.
► Unusally warm appearance of the storm tops caused by a tropopause deformation.
► Cold-ring vs cold-U storm top features depend on the storm-relative upper level winds.
► Cold-U features related to the deviant cell propagation.