Subtropical transition events (STT) are a challenge for forecasting and research due to the hybrid characteristics
they give to the cyclones. The ability and skillfulness of the HARMONIE-AROME model to reproduce the cloud
structure and convection associated to the October 2014 STT is here evaluated. Brightness temperature, cloud
top height and accumulated precipitation are assessed against satellite data using traditional skill scores and
object-based techniques specific to forecasting spatial evaluation. The results present differences in the simu-
lation of the cyclone between the periods before and after the transition. They also show a very good perfor-
mance of the model in the location of the events and a good simulation of the intensity of the variables. The
performance is sub-optimal for the estimation of the sizes of the convective objects. Brightness temperature and
cloud top heights yield very good results in general, with a slight overestimation in both cases. However, the
model struggles to capture the accumulated precipitation. There is scarce work evaluating the HARMONIE-
AROME model in this type of events; nevertheless, the results are in line with those produced by the simula-
tions with other numerical models. The overall performance of the model is very adequate, although it might be
hindered by the internal stability of the model produced by the deep-convection computation.
