Fig. 1

Lightning mapping observations of the 24 August 2016 storm by the Kennedy Space Center Lightning Mapping Array. a Overview of the height-time evolution of the 3-h storm, b 10 min of enhanced activity during the bracketed interval of a, colored by the lightning-inferred polarity of the storm charge (red = upper and lower positive charge, blue = mid-level negative charge), showing the NBE events (black), c zoomed-in view of 6 s of high-rate NBE activity (~40 NBEs within 1 min), indicated by the bracket in b, colored and sized by VHF source power and showing NBEs 1, 2, and 9. Note that the initial high-power sources of the NBEs (large diamond markers) were mis-located in altitude from the subsequent, smaller, and correctly located lower-power sources (blue markers), with NBE 1 altitude being particularly incorrect (see Methods). The low-power sources indicate that all 10 NBEs occurred at similar altitudes between 13 and 15 km MSL, immediately below or within the inferred upper positive charge region. d–f Plan and vertical cross-section views of the storm charge structure, colored by charge as in b and showing that the NBEs occurred in close proximity to a positively charged western anvil of the normally electrified storm. The inset in the east–west cross-section of d shows the full-duration INTF centroid observations for each of the three NBEs relative to the storm location, with marker colors corresponding to relative VHF power. The inset shows that each NBE had a vertical extent of ≃1.5 km on the lower edge of the upper positive charge region. The plan view of e shows the NBE locations as white circles. The cyan boxes in d and f indicate their locations in the vertical cross-sections. The black triangle in e indicates the INTF location at KSC