Characteristics of Lightning within Electrified Snowfall Events using Lightning Mapping Arrays.

Area of Science:

• Atmospheric Science
• Meteorology
• Electromagnetism

Background:

• Thundersnow events are rare and poorly understood, particularly the characteristics of lightning within them.
• Lightning mapping arrays (LMAs) provide detailed in-cloud lightning data, complementing national networks like the National Lightning Detection Network (NLDN).

Purpose of the Study:

• To characterize the in-cloud component of lightning flashes during thundersnow events.
• To assess the correspondence between LMA-derived lightning data and NLDN observations.
• To investigate lightning's interaction with the built environment during these events.

Main Methods:

• Analysis of 34 lightning flashes from four thundersnow events using data from LMAs.
• Comparison of LMA observations with data from the NLDN.
• Detailed examination of individual flash structures, polarity, and spatial extent.

Main Results:

• Lightning flashes in thundersnow events were primarily of normal polarity.
• The spatial extent of flashes varied significantly, with a mean area of 375 km².
• An average of 2.29 NLDN flashes were recorded per LMA flash, with some flashes having zero NLDN detections.
• Eleven flashes initiated from tall human-made objects, and NLDN sometimes detected return strokes instead of initial upward leaders.

Conclusions:

• Thundersnow lightning exhibits distinct characteristics compared to typical lightning.
• Discrepancies exist between LMA and NLDN data, highlighting the need for advanced lightning detection methods.
• Lightning's interaction with tall structures during thundersnow warrants further investigation.