| Users are required to read the "IMPORTANT INFORMATION TO USERS" before they use the Lightning Information Service on this Website.
Basics of Lightning 1. There are two common types of lightning i.e. cloud-to-ground and cloud-to-cloud lightning. Cloud-to-ground lightning occurs when there are electrical discharges between cloud and ground. Cloud-to-cloud lightning is mainly cloud flashes, which are electrical discharges within a single cloud or between different clouds. Cloud-to-cloud lightning are usually, but not always, a precursor to the potentially more dangerous cloud-to-ground lightning. 2. Most lightning strokes occur within 5-6 km of a thunderstorm cloud. In the absence of a thunderstorm in a location, lightning strokes from a distant thunderstorm cloud more than 10 km away could still affect that location. MSS Lightning Information Service (LIS) Website 3. The information here is based on data from MSS's Lightning Detection System (LDS). The LDS comprises a network of four lightning sensors located islandwide that detects cloud-to-ground and cloud-to-cloud lightning strokes. MSS's LIS Website displays cloud-to-ground and/or cloud-to-cloud lightning strokes within the last 30 minutes. The information is updated at 5 minute intervals. Accuracy 4. The average location accuracy of the LDS for cloud-to-ground lightning detected within Singapore when all the sensors are in operation varies from about 200m within the LDS network to about 1-2km near the LDS network boundaries in particular the western and eastern ends of Singapore. For cloud-to-cloud lightning, the average location accuracy is around 2 km. The location accuracy is reduced when not all the sensors are in operation. The actual location of lightning strokes may thus differ from the position displayed on this Website, within the range of the lightning location accuracy. 5. The lightning detection efficiency of the LDS for detection within Singapore is estimated to range between 90% and 95% when all sensors are in operation. The detection efficiency is reduced when not all the sensors are in operation. There is thus no guarantee that all lightning occurrence can be detected, and false detection of lightning strokes by the LDS may also occur. Timeliness 6. The display of lightning and related information on this LIS Website is dependent on the computation and communication time. There is normally a delay of a few minutes in the data that is displayed. The reliability and availability of the information is also dependent on telecommunication and power services, which could disrupt or cause an interruption in the display of information on the LIS Website. Weather Radar Layer 7. The Weather Radar Layer in this LIS Website shows areas affected by rain/showers as detected by MSS's Polarimetric Meteorological Doppler Weather Radar. This radar is tuned to detect precipitation/rain above a minimum intensity. Occasionally some non-weather related atmospheric phenomena might be shown on the radar layer. The data in the Weather Radar Layer is updated every 5 minutes. Thundery Showers Layer 8. The Thundery Showers Layer in this LIS Website shows the forecast of thundery showers for the next hour. The forecast accuracy is limited and dependent on the nature of the weather systems in Singapore. The data in the Thundery Showers Layer is updated every 5 minutes. |
