A version of the United Kingdom Meteorological Office mesoscale model is used to simulate the severe storm that affected Melbourne on 22 December 1990. The storm developed in the western part of Victoria on a pre-frontal trough associated with a Southern Ocean depression. The storm environment was characterised by strong shear in the lowest 3 km and this led to the storm splitting and developing severe characteristics including hail and tornadoes. The model was run at two resolutions nested in the operational regional model of the Australian Bureau of Meteorology. At 20 km resolution, a realistic rain-band is produced, and good predictions are made of the surface conditions before and after the passage of the trough. At 2.5 km resolution, individual showers are predicted. The trough is marked by development of a line of vigorous showers in the Melbourne area. One, in particular, has low-level winds in excess of 50 kn and rain rates of over 10 mm h- 1, offering excellent guidance to the storm's actual development.
B. W. Golding (Tue,) studied this question.