BLAAST (Buoyancy contribution and Loading effect of rain water to Air parcel Acceleration in Squally Thunderstorms) for downburst/squalls nowcasting was developed with reference to the descending forces that created a downburst, namely the combined effect of negative buoyancy as a result of evaporative cooling of falling rain drops and the water loading effect on an air parcel. The latter effect manifested itself under radar surveillance as VIL, a quantity readily available from most radar processing software. If the resultant force acting on an air parcel was pointing downward, a downburst was considered triggered. The maximum gust winds induced on the ground were estimated by converting all the potential energy (due to negative buoyancy and water loading) and kinetic energy (due to horizontal momentum) of the parcel at its descending level into kinetic energy at the ground level. Reference: Applications of the Hong Kong Observatory Nowcasting System SWIRLS-2 in Support of the 2008 Beijing Olympic Games

BRINGO (Buoyancy-supported Rimed Ice Nugget and Graupel Overhang) is designed on the automatic detection of overhanging radar echoes, typically found in hailstorms as a result of strong inflow and buoyancy in the riming process for ice or graupel. Specifically, a hail-prone overhanging echo was identified by BRINGO as intense reflectivity pixels exceeding 60 dBZ at altitudes above 3 km, with VIL in the lowest 1-2 km less than 5 mm. Reference: Applications of the Hong Kong Observatory Nowcasting System Swirls-2 in Support of the 2008 Beijing Olympic Games

DELITE (Detection of cloud Electrification and Lightning based on Isothermal Thunderstorm Echoes) is an innovative algorithm for lightning warning. It selects radar and other parameters most relevant to the microphysical processes leading up to the electrification of a cumulus cloud. This includes radar reflectivity at constant temperature levels (0°C, -10°C, and -20°C), the thermal profile of the troposphere (from either numerical weather model analysis or the latest available radiosonde data), the echo top height and the vertically integrated liquid (VIL). Cloud-to-ground lightning initiation is expected if prescribed thresholds are exceeded. Reference: Applications of the Hong Kong Observatory Nowcasting System Swirls-2 in Support of the 2008 Beijing Olympic Games