A diagnostic study of cloud physics and lightning flash rates in a severe pre‐monsoon thunderstorm over northeast India

Abstract

Numerical simulations of a thunderstorm event that occurred in the pre‐monsoon season over the North‐Eastern region of India (NEI) and Bangladesh are performed using Weather Research and Forecasting (WRF) Advanced Research Weather Research and Forecasting Model (ARW, version 3.8.1). Doppler weather radar indicates severe convective activity lasted for more than 10 hr. These extremely deep convective clouds with minimum cloud‐top temperature −70 °C at 19 km were triggered by the mixing of a moist air mass transported from the Bay of Bengal in the south and dry air transported from the northwest. A cyclonic circulation observed over the Tibetan plateau is likely to be associated with the strong southerly low‐level wind over NEI, as the plateau acts as a source of heat‐lows during the pre‐monsoon season. The coexistence of ice particles and supercooled water in the storms resulted in a large number of lightning flashes during the storm as observed from the Tropical Rainfall Measuring Mission Lightning Imaging Sensor (TRMM‐LIS). Co‐location of supercooled cloud water droplets helps in forming graupel through riming that plays a vital role in these convective systems. Lightning flashes calculated from WRF simulation using the Morrison microphysical and cloud top height based dynamical lightning parametrization scheme was found comparable with the observed flashes from TRMM‐LIS. Since the WRF model could simulate the thunderstorm, we recommend using this state‐of‐the‐art regional model in thunderstorm and lightning predictions for northeast India which would be useful in preparedness for such extreme events.

Characteristics of Orographic Rain Drop-Size Distribution at Cherrapunji, Northeast India

“…The unstable atmosphere can produce buoyancy-generated strong updrafts, thus triggering convection development and cold rain processes in the convection. Lightning observations have indicated a high frequency of flashes over the Meghalaya Plateau [30], implying the existence of cold rain processes, as electrification is associated with supercooled water and graupel [64].…”

“…Monsoons in this area begin in June, bringing heavy rain during the monsoon season from June to September. A considerable amount of rainfall occurs during the premonsoon season from March to May (e.g., [27]); the severity of the storms is also higher during this time period [28][29][30]. The purpose of this study was to elucidate the characteristics of orographic rain DSDs at Cherrapunji and the dependence on the rain rate and LNSD.…”

Lightning Characteristics Over Humid Regions and Arid Regions and Their Association With Aerosols Over Northern India

“…1 b). During the pre-monsoon, especially during April and May, this region experiences thunderstorms with severe lightning, known locally as “nor'westers” or “Kal-Baisakhi,” which bring human activities to almost a standstill (Choudhury et al, 2020 ; Jain et al, 2013 ; Mahanta et al, 2013 ). Typically, this region receives 0.06–0.14 lightning flashes/km 2 /year (Fig.…”

The diurnal cycle of the lightning potential index over the Mexican tropical continental region during tropical cyclone Bud

“…and q i , q g , and q s are the mass mixing ratios for cloud ice, graupel and snow, respectively. Because the LPI is calculated from cloud microphysical fields and vertical velocity, it is sensitive to microphysical parameterizations in numerical weather prediction (NWP) models (e.g., Bovalo et al, 2019;Choudhury et al, 2020;Rajeevan et al, 2010). Lightning has a strong microphysical origin, which is important for electrical charge transfer and buildup inside thunderstorms, although there is not a firm theory.…”

“…Although the LPI is an important index, lightning proxies have also been used to simulate lightning indirectly (e.g., Barthe et al, 2010; Bovalo et al, 2019; Choudhury et al, 2020). They are mainly based on relationships between lightning flash rates and storm parameters such as vertical fluxes of ice, graupel, and snow during updrafts (Cecil et al, 2005; Petersen et al, 2005).…”