A strong squall line on a frontal boundary motored across the Upper North Island on the last day of November which finished out a very stormy month indeed. 6 Thunder day were recorded for the month along with near record rainfall.
As the squall line moved through it triggered lightning strikes.
The unusually loud booming sounds of thunder reported seemed to be caused by 'Inversion thunder'.
Taking a close look at the weather balloon data from today’s MetService 11am measurements at Whenuapai, it shows there was a temperature inversion at around 1km above the earth surface. This has likely caused the atmospheric acoustic phenomenon called ‘Inversion thunder’, which is when a warmer layer of air traps the sound and then refracts it back towards the ground.