The Roles of Rainfall Rate and Cloud Top Height in Lightning Activity During Northeastern Monsoon in Malay Peninsula

This paper presents an analysis of two tropical storms that occurred during the northeastern monsoon season over the Malay Peninsula. The first storm, on 17 December 2024, involved both lightning and rainfall, while the second, on 26 December 2024, involved rainfall only, without lightning. Two automated weather stations (AWS) were used to monitor meteorological parameters, namely rainfall rate, temperature, relative humidity, wind speed, and wind direction. The Constant Altitude Plan Position Indicator (CAPPI) radar echo was used to obtain the precipitation intensity and cloud top height (CTH) used to obtain cloud coverage and maximum height of the cloud structure. Fast antenna (FA) and magnetic field antenna systems were used to determine the types of lightning flashes and localized the lightning strikes using magnetic direction finder (MDF). The first storm was a convective cloud formed at the base of Mount Datuk consisting of heavy rainfall intensity with a maximum rainfall rate of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$80 ~\text{mm} / \mathrm{h}$</tex>, CTH of 9.25 km, and accompanied by lightning activity. A total of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{1 1 8}$</tex> flashes were recorded during the day, with 58 negative-cloud-to-ground (NCG), 38 positive narrow bipolar events (PNBE), and 23 positive intra cloud (PIC). The second storm was a combination of two isolated convective clouds. Despite recorded moderate rainfall intensity with a maximum rainfall rate of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$50 ~\text{mm} / \mathrm{h}$</tex>, and maximum CTH of 5 km, no lightning activity was recorded during the entire storm life cycle. It can be suggested that the main factor for the tropical lightning discharge to happen was facilitated by very strong convection.