The nowcasting procedures of the convection was analysed with plain satellite imagery as well as RGB, several NWP from ECWMF and Aladin. Also GII, NWCSAF, INCA and Radar were introduced to monitor the convection over Central Europe.
In the IR10.8 and WV6.2 images the cells are easy identified due to the cold cloudtops, over Germany and Austria. From WV6.2 it is observed that most of the cells develop at the boundaries of moist to dry air. With the artificial RGBs a comparison is made between the Airmass, Dust and Severe Convection RGB. The latter RGB is very useful as it is able to discriminate between large and smaller iceparticles. With this in mind it is possible to diagnose which cells further develop and which not. The disadvantage is however that this RGB makes use of visible channels and therefor no monitoring in the evening or early morning hours is possible.
Both ECMWF and the smaller scale LAM model Aladin show an extremely unstable situation in the warm sector of a frontal system over the North Sea. The convection is tight to a thickness ridge and in the antcyclonic flow the windfields shows especially near the surface continuing confluent movements. This is also reflected in the convergence at 925 hPa. In small scale situations like convections the higher resolution models is in this case one big advantage as smaller structures can be identified and related to the convective development.
In the Nowcasting chapter four different methods were presented to monitor the convection discussed in this case.
From the NWCSAF, and for the early nowcasting of convection, one of the most important products is the SAI which stands for Stability Analysis Imagery. This product which is computed for the cloudfree area takes the different brightness temperatures of MSG thermal channels to calculate the instability via an algorithm. From the results it became clear that It would last untill the morning hours before the SAI showed negative results (e.d. Lifted Index was presented) and the indication the atmosphere was unstable. When it did finally retrieve negative results it did in abundance as the whole of Central Europe was covered by a negative LI making an exact diagnosis on where the new convection would start impossible.
A similar product like the SAI is the GII which stand for Global Instability Index and is also computed by an algorithm using a priori information from ECWMF and the BT from the 6 thermal channels onboard MSG. Three products that describe instability where presented. They were the K-indes, the Lifted Index and the Total Precipitable Water. From K.index and the Lifted Index we learned that the values that were calculated by the GII algorithm were correct as a direct comparison with values from radiosoundings was possible. Already at an early stage there were high values for KI and negative values for LI computed so that at an early stage one could see where the next convection would likely start. In the animation three different timesteps were chosen and the stability indices gave a good indication on where the next development would start. The TPW also proved to give correct values.
A third nowcasting method is presented with INCA. From the nowcasting system five different products were selected and presented Three of them are stability indices and one was Moisture Convergence. Interesting enough all three of the stability parameters already gave signs that it would be a convective day very early on the 19th June. Three areas really popped out as being extremely unstable that were Upper Austria, the northeastern part of Lower Austria and Styria, close to the border with Slovenia. In the latter area however no convection occured. From the radiosounding which was presented we learned that over Budapest there was a strong capped inversion that might have prevented convection to trigger. Such a situation is most likely also the cause that nothing occurred over Southern Styria. More to the north however orographic lifting along the Alps triggered the first cells over Austria on the 19th. Also over Lower Austria already at 11UTC the first cells emerged. In Upper Austria the situation was unstable but it would last till the late afternoon when cells from Switzerland moved in bringing thunderstorms to that area. The Moisture Convergence is extremely usefull as it realy pinpointed the exact location were maximum convective forcing occured. Along the Alps were most of the convection started on the 19th several of these areas were observed. The MOCON in combination with a stability parameter like CAPE would give the best result when nowcasting convection.