Shillong, Nov 11: A sustained hailstorm led to gridlocked traffic and choked and overflowing drains in Shillong today, though residents. The hailstorm that hit Shillong on Wednesday morning was triggered by a convective weather system and was a short-lived event, the India Meteorological Department (IMD) has said, while warning of continued thunderstorms and rainfall in parts of Meghalaya until Thursday.