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  • Weekly Weather Event -Week of Sept. 9

Weekly Weather Event -Week of Sept. 9

September 13, 2019

On Thursday September 12th, a severe thunderstorm rolled through large portions of Wisconsin and northern Illinois, bringing more rain to already waterlogged ground. Flash flood warnings were issued throughout the southern half of the state and tornado watches were issued in south-western Wisconsin. In addition to the rain, the storm also brought scattered hail, strong wind gusts, and generated a significant amount of lightning and thunder.

Lightning is perhaps the most visible byproduct of thunderstorms, lighting up the sky with a large spark of electricity between clouds, the air, or potentially the ground. Under normal circumstances, air acts as an insulator between positive and negative charges in the clouds and between the clouds and the ground. As these opposite charges build up, however, the air begins to lose its insulating properties. When those properties break down, this results in a rapid discharge of electricity that we see as lightning.

There are many types of lightning that can be observed during a storm. Most lightning never reaches the ground, instead flashing within the cloud (intra-cloud lightning), between clouds (cloud-to-cloud), or dissipating in the air (cloud-to-air). There are approximately 5-10 times as many cloud-based lightning flashes when compared to cloud-to-ground lightning strikes. When lightning does make it to the ground, it typically strikes the tallest object near the concentration of charge.

Approximately 47 people in the United States die each year from lightning strikes. By and large, these deaths are preventable. Seek shelter at the first sighting of lightning and thunder, stay away from water, metal, and tall objects, and avoid wide open areas.