The SWIRLS Ensemble Rainstorm Nowcasting (SERN) system is an ensemble system that generates probabilistic quantitative precipitation nowcast (PQPN) to support the operation of the rainstorm warning system in Hong Kong. The ensemble comprises 36 members generated by perturbing parameters adopted by the variational optical flow algorithm "VarFlow". Every 6 minutes PQPN based on outputs of the 36 members are computed to assess how likely and how heavy the rainstorm will become. PQPN are visualized through the web interface STAMP (SWIRLS Time-Series And Mapped Probabilities).
Probability of 60-minute Rainfall exceeding 50 mm/h from SERN/STAMP based at 09:00 on 2017/05/24 (HKT)
Rainfall Intensity at medium probability from SERN/STAMP based at 09:00 on 2017/05/24 (HKT)
SIP (SWIRLS Integrated Panel) and ARROW (Automatic Rainstorm Related Objective Warnings)
The SWIRLS Integrated Panel (SIP) is developed to provide weather forecasters with a consolidated view that summarizes essential forecast tools in support of the operation of the rainstorm warning system. As a component of SIP, "Automatic Rainstorm Related Objective Warnings (ARROW)" serves as an objective warning guidance based on the best verified algorithm.
SIP with ARROW visible at 09:00 on 2017/05/24 (HKT)
STIR (Special Tips for Intense Rainfall)
STIR is a tool that automatically compiles messages in natural languages (Chinese and English) based on rain gauge and lightning observations, QPE, QPF and severe weather nowcast. It intelligently selects reporting intensity thresholds from rainfall distribution and adapts to user-specified word count limit. Automatic messages from STIR may serves as captions to rainfall maps and for various reporting purposes.
Automatic messages generated from STIR with user-specified word count at 11:30 on 2017/05/24 (HKT).