In December, 2015, the intense storm cell that approached Kurnell from the south was formed in a trough fed by warm, moist air to the east and north-east of the developing system. Radar imagery showed that the Kurnell storm originated around 35S on the coast, to the north of Sydney.   The convective storm moved along the coastline northwards, undergoing further intensification. Cyclonic circulation developed in association with the storm intensification. The cyclonic circulation supported the storm by supplying warm moisture air over the ocean.

Development of the UM for high-resolution application is conducted under the international RMED project. A particular model configuration, in terms of the parameters that define model numeric, physics, and so on, is labelled as "RA<V><D>", the "RA" being short-hand for "Regional Atmosphere", the <V> being a version number, and the <D> being  the type of domain over which the configuration applies. Currently there are two versions ("1" and "2"), and two domain types, tropical ("T"), and mid-latitude ("M"). In this study we carried out 1.5km UM simulations for the Kurnell storm, using all four RMED configurations: RA1M, RA1T, RA2M, and RA2T. Note that the newer RA2 configurations include improved cloud microphysics relative to their RA1 counterparts.

Our results show that the RA2M model simulation is the most accurate simulation, compared to observations of the storm track forecast and starting time. This simulation showed rotating wind associated with the storm, which supplied the moisture to further promote the storm's development.  When the model resolution was enhanced to 1km, the storm simulation was further improved.

 The RA1T and RA2T simulations failed to produce the convective system along the coast, so for this storm, middle latitude model configurations are better choices over the tropical domain configurations. Sensitives of model results to the model physics configurations could be case dependant.