A Climatology of the Hight Resolution Ensemble Forecast (HREF) Heavy Rainfall Probabilities

The difficulty of forecasting heavy and extreme rainfall has been exacerbated by an increasing number of events occurring on shorter time and smaller spatial scales. The predictability of such events is generally low and to help tackle the challenge of identifying the rainfall risk, forecasters are increasingly turning to probabilistic forecasts. However, the climatology of how often heavy rain probabilities are predicted in ensemble systems has not been widely researched and verified. With this in mind, we will evaluate the probability of precipitation exceeding thresholds from the High Resolution Ensemble Forecast (HREF). The thresholds evaluated will be both fixed (e.x. 5”/6h) and variable (e.x. Average Recurrence Intervals) thresholds, produced by the Environmental Modeling Center for the HREF and compared with the Multi-Radar Multi-Sensor Gauge Corrected precipitation observations. Such an evaluation will help forecasters calibrate to the ensemble probability fields and their current representativeness.