Every 2 minutes Window reads NEA's lightning detectors, rain radar and rain gauges around Bishan. It tells you when a thunderstorm is closing in and roughly when it will arrive, when to stay indoors because lightning is within 10 km, and when rain is likely in the next two hours.
Haze for Bishan comes from NEA's Central region monitors (24-hour PSI and 1-hour PM2.5). The nearest rain gauges are Macritchie Reservoir (1.1 km) and Toa Payoh North (1.7 km).
Alerts for Bishan on Telegram: @WindowSingaporeBot. A heads-up before storms and when haze turns unhealthy; nothing for maybes.