Verification of quantitative precipitation forecast guidance from NWP models and the Hydrometeorological Prediction Center for 2005–2007 tropical cyclones with U.S. rainfall impacts

The National Weather Service's Hydrometeorological Prediction Center (HPC) routinely issues 6-hourly quantitative precipitation forecast (QPF) guidance for days 1 through 3 over the Continental United States. This guidance is used by National Weather Service (NWS) River Forecast Centers (RFCs) and Weather Forecast Offices (WFOs) for the preparation of river forecasts and gridded NWS precipitation products. In situations where tropical cyclones (TC) impact the U.S. (or elsewhere), HPC also provides QPF guidance to the Tropical Prediction Center/National Hurricane Center (TPC/NHC) for inclusion in public TC advisories to raise awareness of the rainfall hazards associated with the TC. These rainfall hazards can often be more devastating to life and property than hazards related to strong winds and storm surge. Additionally, rainfall impacts can extend well inland and persist for days after the TC makes landfall and dissipates.

A wide variety of guidance from numerical weather prediction (NWP) models is available to forecasters at HPC in preparation of QPF guidance associated with TCs. This output includes guidance from the Global Forecast System (GFS) and North American Mesoscale (NAM) models run by the National Centers from Environmental Prediction (NCEP). Additionally, QPF guidance from the global model run by the European Centre for Medium Range Weather Forecasting (ECMWF) is available to HPC forecasters in 12-h increments, not in the 6-h increments needed to prepare HPC's QPF guidance products. Currently, ECMWF QPF output is not available to the WFOs or RFCs.

Verification of 24-h day 1 QPF guidance from the GFS, NAM, ECMWF, and HPC will be presented for TCs with CONUS rainfall impacts for which HPC had advisory responsibility from the 2005, 2006, and 2007 hurricane seasons. Verification data will include qualitative comparisons of forecast and observed precipitation as well as threat scores and bias computations for both individual TCs as well as all TCs in a given season.