The Lake-Effect Electrification (LEE) Project: Differences in Lightning Flash Characteristics During the 17-20 November 2022 Event

The Lake-Effect Electrification (LEE) Project was conducted from September 2022 until March 2023 with the goal of understanding the electrical charge structure of cool season lake-effect storms east of Lake Ontario and the associated lightning. During the 17-20 Nov 2022 storm, 148 lightning flashes were observed by the combined National Severe Storms Laboratory and Georgia Tech Research Institute lightning mapping array (LMA) network. These flashes were sorted into three categories based on where they were located: on the Canadian side of Lake Ontario, within 15 km of the NY lake shore, and farther than 15 km of the shore. Based on those criteria we documented 12 Canadian flashes, 25 near-shore NY flashes, and 109 inland flashes during the event. Two flashes were not diagnosed as they were near the 15 km border. The Canadian flashes will be studied at a later time as they were farther from the LMA network.

Specific characteristics analyzed included the predominant leader polarity for each flash, the LMA source mode altitude, the direction of lightning propagation in relation to the lake-effect band, and whether or not the flash propagated along a region with greater radar reflectivity. These characteristics all tell different stories about the atmospheric conditions at the time and can be compared through different storms. Notable findings included that 73% of inland flashes were composed of predominantly positive leaders (traveling into a negative charge region), ascertained through the leader’s velocities relative to flash initiation, while 48% of shore flashes were predominantly negative leaders (traveling into a positive charge region). Twenty percent of inland flashes and 22% of shore flashes evenly demonstrated both positive and negative leaders within one flash. The most common altitude for LMA sources was 1.9 km MSL inland and 2.5 km MSL near shore. It was also observed that 83% of inland flashes and 89% of shore flashes tended to reside within the greater reflectivity. A majority of the inland flashes were recorded above a wind turbine field and the near-shore flashes were either over the lake or above towers close to the lake suggesting a strong correlation between the two factors.