Todays forecast session started with a verification of the Outlooks and Mesoscale Discussions of the day before. The 50% thunderstorm line of the Day1 outlook was quite well placed. It covered almost all the thunderstorm activity. Concerning the LVL2, many reports reached the ESWD database, whereas the most prominent was excessive precipitation. This was true for central and northern parts of the LVL2 while for the southern region only a few reports arrived until now. So it may happen that it finally will not verify.
LVL1 and LVL2 should have been extended more to the northeast to also cover the excessive rain events in the Ruhr area. The reason that it was not done is probably that it was right at the edge of the domain and the team concentrated more on Northeastern France and Belgium.
What was interesting: One nowcasting team issued a mesoscale discussion for Northern Germany also with the probability of tornadoes It finally happened that indeed a tornado occurred that led to a case of emergency in eastern parts of Hamburg. So it was quite a good discussion.
The tornado was probably a non-supercellular one, given low wind velocities in upper levels and a strong convergence in the surface flow. Also no rotation tracks or mesocyclone detections have been found.
It was quite interesting that NowcastMix was able to cover both, the severe rainfall event over the Ruhr area as well as the tornadic storm near Hamburg. In both cases an extreme severe weather warning was shown.
After the verification the two teams prepared an outlook for Day1 and Day2, respectively. Today it was much more difficult as the day before. Concerning Day1 many clouds and even precipitation was present in the morning hours. So it was quite questionable if the atmosphere may recover troughout the day. Eventually, only a LVL1 was issued. Concerning day 2 no LVL area has been issued at all, due to the many uncertainties. However it might become neccasary that one LVL1 is needed when looking on the data tomorrow … especially concerning the Tuscany area which shows quite a good low level convergence.
Looking forward for the afternoon session and what indeed will happen in the area of interest.
