Three factors come together to inundate Gangtok with pre-monsoon thunderstorms

GANGTOK, 20 April: A bright and sunny day suddenly turns into a gloomy evening and as heavy showers hit the capital accompanied by thunder, lightning and even hail at times, a slight chill in the air can be felt.
Speaking to NOW!, Gangtok Meteorological Centre In-charge, GN Raha, informed that the period between 01 March to 31 May is the pre-monsoon season and thunderstorms usually occur during this time. He explained that three factors lead to thunderstorms - solar heating or insulation, moisture incursion and triggering forces like some systems of trough, cyclone, low pressure etc.
Mr Raha mentioned that at present, Gangtok is recording temperatures slightly more than 20 degree Celsius everyday so there is good insulation, and good moisture coming from the Bay of Bengal and North-South trough is present over the Sub-Himalayan West Bengal and Sikkim to North Bay of Bengal. He further explained that due to the presence of all three favorable factors, Gangtok has been experiencing regular rainfall along with heavy rainfall and hail on some days.
The Met Centre has recorded 53 mm rainfall over Gangtok and 54 mm rainfall over Tadong between 13 April night to 14 April morning. Another good rainfall of 60 mm over Gangtok and 45 mm over Tadong was recorded between 16 April night to 17 April morning and then between 18 April night to 19 April morning Gangtok recorded 53 mm rainfall while Tadong had 62 mm rainfall. Likewise, rainfall recorded between 19 April morning to 20 April morning was of 36 mm over Gangtok and 74 mm over Tadong. More than 65 mm of rainfall is termed as heavy rainfall.
Mr Raha further explained that due to a local phenomenon there has been rainfall in Gangtok, Mangan and some other parts and not the entire state.