COALITION-3 predicts the severity of the thunderstorm expressed as TRT rank for the next 45 minutes and has an update cycle of 5 min. The result covers Switzerland and it’s surrounding, where all input measurements are available. The spatial resolution of the COALITION-3 products is 1 km x 1 km.
Figure 4 shows an example of a nowcast for a thunderstorm in Baden-Württemberg in Southern Germany at the 7th of August 2018. On the left hand site shows the radar image at 10:25 UTC. The white oval indicates that the current state of the thunderstorm is below the lowest warning level. The white arrow indicates the expected motion of the thunderstorm. The colors shown along the direction of movement indicate the expected severity of the thunderstorm within the next 30 minutes. On the right hand site, the same thunderstorm is shown as a temporal diagram. On the y-axis, the thunderstorm severity expressed as TRT rank is plotted. The thunderstorm warning levels used by MeteoSwiss are indicated as green (moderate thunderstorm), yellow (severe thunderstorm) and red (very severe) region on the y-axis. The black line shows the development of the TRT rank as it was observed on this day. The cyan line illustrate the assumption that the severity is constant. The purple line shows that COALITION-3 prediction of the thunderstorm severity. COALITION-3 correctly captures the intensification of the thunderstorm, including the exceedance of warning levels for moderate (green) and severe (yellow) thunderstorms within the next 30 minutes.