Lightning Density and Thunderstorm Initiation in the Lake Victoria Region in East Africa

The Lake Victoria basin in eastern Africa is home to over 30 million people, over 200,000 of whom are employed in the fishing or transportation industries on the lake, and approximately 3,000-5,000 of whom are killed by thunderstorms each year. Using new, continuous observations of total lightning (cloud-to-ground flashes + intracloud pulses) from the Earth Networks Global Lightning Network (ENGLN), we examine climatological lightning occurrence and the initiation of high-impact, prolific thunderstorms in the Lake Victoria region. Thunderstorm cluster analysis reveals initiation hotspots associated with the mountains and highlands northeast of the lake, with the most prolific clusters initiating 1-2 hours earlier than the average cluster. Most daytime thunderstorms dissipate without reaching Lake Victoria, and annually 85% of clusters producing over 1,000 strokes over the lake initiate in situ during the night. The initiation times of prolific Lake Victoria clusters exhibit a bimodal seasonal cycle: during the equinox seasons, clusters initiate about 5-6 hours earlier, and are more likely to initiate over land and propagate over the lake, compared with the solstice seasons.