Future rainfall is useful in hydrologic prediction, whether it is flooding or operations impacted by sewer overflows. Quantitative precipitation forecasts (QPF) rely on several technologies depending on required lead-time and resolution.
PreVieux takes current radar rainfall and moves it forward in time and space, and updates future rainfall motion with each scan of the radar. This type of QPF is called a ‘nowcast’ because it evolves from current rainfall motion, growth and decay to make short-term forecasts. Accuracy of the QPF is enhanced by bias correction of the rainfall used to make these future projections.
Longer-term QPF going out to 18 hours leverages the High Resolution Rapid Refresh (HRRR), and then out to 7 days, using the National Digital Forecast Data (NDFD). Both of these products, the HRRR and NDFD, are gridded NWS products generated by numerical weather prediction models, which we make more reliable by filling gaps in the operational data streams.
Proactive notifications based on NWS forecasts are can be managed using Stormwater Forecast