SEVERE STORM TEARS THROUGH THE SUNSHINE COAST HINTERLAND, DECEMBER 30

Storms had been forming quite well near Sydney and to the north into the Hunter, with a very large and severe supercell hailstorm lasting over three hours in the region.  Smaller thunderstorms had also been forming in NE NSW, but it wasn't until just after 4pm that a small line of cells near Gympie started forming in the maximum surface heating of the day.  Initially these cells were weak, and were moving ESE, but one cell gained strength and broke away from the others, heading SE towards the Sunshine Coast at around 5:20pm.  It continued its path, and soon had maximum intensity on radar, and sustained that intensity for nearly one and a half hours!  The Bureau of Meteorology issued a severe thunderstorm warning for the district as damage reports came in:

SEVERE THUNDERSTORM WARNING Issued by the Bureau of Meteorology, Brisbane at 6:31pm EST on Thursday the 30th of December 1999 For the Southeast Coast District A severe thunderstorm near Maroochydore is moving southeast and is expected to affect areas along the southern Sunshine Coast and adjacent hinterland over the next hour. People are advised to secure outside items, move cars under cover and seek shelter.

It was reported as a "mini tornado" by residents and the media, with damage to trees, and some structual damage to houses.  There were reports of hail, particularly in the farming districts on the outskirts of the Sunshine Coast, where there was crop damages. 

Narrow damage path observed at the Mooloolaba turn off and a second path about 500m wide about 4 kms North.

Damage confined to trees and sporadic, the largest being broken branches and snapped trunks to about 12" in diameter.  One 4m Queen palm snapped off at ground level.  One road side hoarding demolished.  Council were on the job with the wood chipper cleaning up.  All tree damage obviously caused by wind from the same direction, i.e., NW wind which corresponds to the storm track which was towards the SE.  No tell tale signs of hail (i.e., no shredded leaf litter), no sign of rotating wind.

As the storm spent most of its time outside of local radar, it was difficult to tell whether the storm was supercellular or not.  However shear was definately supportive of supercells, and supportive of right-moving supercells if one were to occur.  If this storm was actually a supercell, it would have been a right moving supercell.  However, due to limited radar coverage, it is difficult to tell.