Correction of Precipitation Forecast under the Northeast Cold Vortex in the Haihe River Basin

Using the precipitation samples from the northeast cold vortex in the Haihe River basin, based on the encrypted observation station data and precipitation forecast data produced by the European Centre for Medium-Range Weather Forecasts (ECMWF), we conducted a sliding time window correlation analysis between 24-h precipitation observation and forecast series to re-establish the precipitation forecast series. Then, we matched the frequency with the gamma cumulative probability distribution curve of 24-h precipitation observation, re-established the 1–3-days short-term forecast series on each of the encrypted observation stations to enable correction of precipitation forecast in the Haihe River basin, and checked the forecast effect of the correction of precipitation forecast. The results showed that the period of ECMWF model precipitation forecast is mainly slower than that of the observation of the northeast cold vortex precipitation forecast in the Haihe River basin. The frequency matching method mainly improves forecasting skills by correcting the precipitation magnitude. TS (Threat Score) of the precipitation calibration forecast has been improved for light rain, heavy rain, and rainstorm. The magnitude and area of precipitation calibration forecast need to be close to the observation station data, particularly for the forecasting of heavy rain and rainstorm. However, the model has poor forecasting skills for convective precipitation caused by the northeast cold vortex. Thus, the precipitation-calibration forecast can effectively improve the forecasting skills for heavy precipitation, resulting in good business application prospects.