  An extreme dissipation event in the bulk of a closed three-dimensional
turbulent convection cell is found to be correlated with a strong reduction of
the large-scale circulation flow in the system that happens at the same time as
a plume emission event from the bottom plate. The reduction in the large-scale
circulation opens the possibility for a nearly frontal collision of down- and
upwelling plumes and the generation of a high-amplitude thermal dissipation
layer in the bulk. This collision is locally connected to a subsequent
high-amplitude energy dissipation event in the form of a strong shear layer.
Our analysis illustrates the impact of transitions in the large-scale
structures on extreme events at the smallest scales of the turbulence, a direct
link that is observed in a flow with boundary layers. We also show that
detection of extreme dissipation events which determine the far-tail statistics
of the dissipation fields in the bulk requires long-time integrations of the
equations of motion over at least hundred convective time units.
