Supercell lightning is lightning that is produced during a supercell thunderstorm, the least common, yet the most severe of all thunderstorms. Supercell lightning occurring during a supercell thunderstorm can be deadly, with tens of thousands of lightning strikes or very few lightning strikes at all. The type, amount and severity of supercell lightning depends on several factors related to the supercell thunderstorm.
Basic Facts About the Supercell
According to Absolute Astronomy, supercells are usually isolated from other thunderstorms, with a mesocyclone, which is a quasi-steady, deep, continuously rotating updraft. The presence of mesocyclones is the feature that sets supercell storms apart from other types of storms. Supercells deviate from the mean wind of a thunderstorm and are said to be left movers or right movers. Right mover supercells are the most common, but also the most severe. The supercell can sometimes develop into separate updrafts, which in turn spawns two supercells, a right mover and left mover.
Supercells are capable of producing extremely violent weather, and in addition to severe lightning, supercells may cause very heavy rains, flooding, damaging winds and hail; yet only about 30% produce tornadoes. But of those supercells from which tornadoes do develop, the tornadoes are most likely to develop at maximum mesocyclone core strength.
There are three categories of supercells and the severity may well depend on whether the storm is a classic supercell, low precipitation (LP) or high precipitation (HP) supercell. In “Structure and Dynamics of Supercell Thunderstorms,” the National Weather Service in Louisville, Kentucky says that classic supercells characteristically have a hook on the right rear side of the storm. This hook is significant of the presence and location of strong mesocyclones. High Precipitation supercells exhibit a kidney bean shape in the front of the storm which is indicative of a mesocyclone with heavy rains. HP supercells are capable of producing multiple threats of severe weather such as torrential rains, hail and damaging winds.
The tornadoes spawned from high precipitation supercells can range from weak to violent, with more intense supercell lightning, either cloud to ground or intra-cloud, than other types of supercells. The HP supercell is more common in the Eastern United States and some areas of Eastern Canada. Lightning is rarer in low precipitation supercell storms, and when it does occur, the lightning is more likely to be intracloud lightning, rather than cloud to ground.
Low precipitation supercells can be deceptive at first glance and result in danger to those caught out in the LP supercell. In fact, though weak tornadoes are most likely to occur with a LP supercell, the weak reflection on radar can in fact not reveal a tornado that can be occurring right then. With the characteristics of supercells, one may wonder how widespread and just how severe supercells really are.
Examples of Supercells
On March 6, 2010, supercell storms hit Melbourne Australia, producing dangerous lightning, flash flooding and hail the size of tennis balls. Absolute Astronomy also tells of the supercell that devastated some areas of Belgium in May of 2009. Over 30,000 flashes of supercell lightning illuminated the skies in just 2 hours; winds were so strong that a loaded train was blown off the tracks. In 1936, after rendering its wrath in Tupelo, Mississippi, the entire town of Gainesville, Georgia was obliterated by the fifth largest tornado in U.S. history, when two tornadoes, coming from opposite directions, as sometimes happens during supercells, swept through town. The Digital Library of Georgia has a film available depicting the devastation and recovery efforts.
Storm chasers and others who venture out into severe weather should be aware of potential dangers of the severe weather they go out in, such as an approaching supercell. For most people, severe weather means staying inside and taking other precautions. If supercells are an impending threat, one may want to consider staying away from windows, turning off electronic devices, having the family take shelter in the area of the home that has been designated as the safe spot when severe weather occurs, and making sure there are emergency supplies and a first aid kit nearby.