Update to Weather Forecast Ingest Frequency

As of July 19, 2024 the frequency with which HydroForecast short-term (ST-3), incorporates NOAA’s High-Resolution Rapid Refresh (HRRR) and Global Forecast System (GFS) weather forecast data has been updated. The update allows ST-3 forecasts to take advantage of more up-to-date weather forecast data, improving peak flow timing, especially for rises in flow that result from fast moving weather events. 

Now, HRRR is incorporated into ST-3 forecasts every two hours and GFS data every six hours. Previously, weather forecast information was incorporated into the model twice per day, at the inflow forecast issue time (see support doc on When forecasts are issued for more information).

Below we illustrate the impact of this change through an example during a rain event, with weather forecast data incorporated into ST-3 before (blue) and after (orange) the update. Note the change to the magnitude and timing of precipitation forecast data between the two lines. 

The figure below shows the difference in ST-3 inflow forecasts, where the black line represents observed inflow values with ST-3 before (blue) and after (orange). Notice that the ST-3 inflow forecast based on more frequent weather forecasts predicts the peak more accurately.