Abstract/Summary

Potential Vorticity (PV) elegantly describes synoptic- and planetary-scale dynamics, but it has received less attention on smaller scales. On the convective scale PV is characterised by dipoles associated with convective cells. We show that the PV dipoles are consistent and associated with statistically significant flow anomalies. Our hypothesis is that there is a coherent evolution of the PV dipoles. This hypothesis is tested by tracking convective cells in the nonhydrostatic COSMO-DE Numerical Weather Prediction (NWP) model during nine severe weather events. The 3135 convective cells used in this study are representative of deep moist convection over western Europe in the COSMO-DE model. Composites of the evolution of convective cells are made, and differences between “normal” and intense cells are discussed. Even when averaging over 3135 cells during nine cases, a clear horizontal PV dipole pattern can be seen with associated flow anomalies. Compared to normal cells, intense cells (identified using PV, precipitation rate or vertical velocity) have a more monopole morphology, which resembles supercells. The consistency of the PV dipoles implies that PV is also a useful diagnostic on the convective-weather scale.