A SUPERCELL storm packing heavy rain, lightning, giant hail and strong winds smashed Lismore Base Hospital on Sunday with a lightning strike the probable cause of scaffolding collapsing and piercing the maternity ward roof.
Bureau of Meteorology meteorologist Katarina Kovacevic the combination of low level wind convergence and high level moisture, coupled with upper level support drove the storm to become a supercell.
"The storm formed to the south-west of Lismore about 3.30pm and travelled to the north-east and impacted the hospital and the city of Lismore," she said.
"We received reports of 5cm hail, which is giant hail, from the storm at Tatham, before it impacted Lismore.
"An 87km/h gust was recorded at the Lismore airport automatic weather station at about 4pm."
Ms Kovacevic said the storm then took out the instrumentation on the Lismore airport weather station.
"53mm of rain was recorded in 30 minutes at Belongil Creek about 5:30pm as the storm moved north-east and impacted the Byron Bay area," she said.
"By 6:30pm the storm had moved out to sea but was still quite active over the ocean.
"Those things combined to produce a supercell storm."