NOAA’s Environmental Modeling Center (EMC) has released an upgrade to its Unified Post Processing System (UPP). The UPP developmental version has been cleaned-up, modularized and modernized as part of the UPP re-engineering effort. Additionally, the Relative Humidity (RH) was unified so that the operational North American Model (NAM) algorithm will be used by all models, including the RAP/HRRR and the GFS (for ice conditions). UPP will eventually unify all nine variables that have been computed differently in the RAP/HRRR post processing. Visibility, precipitation types and snow/sleet accumulation are the next variables to be unified, scheduled for Q2FY22.
The UPP V10 will be used operationally in the 2023 implementation of the Rapid Refresh Forecast System (RRFS) and in the GFS V17, which is scheduled for implementation in 2024. The UPP is used operationally in the models maintained by NCEP. The UPP has the capability to post-process output from a variety of NWP models, including WRF-NMM, WRF-ARW, Non-hydrostatic Multi-scale Model on the B grid (NMMB), Global Forest System (GFS), and Climate Forecast System (CFS), and Finite-Volume Cubed Sphere (FV3). The UPP development project is a joint collaboration between EMC, Global Systems Laboratory (GSL) and the Developmental Testbed Center (DTC).
A comparison of the global Relative Humidity (RH) at 500mb, using the current operational GFS algorithm (left) and the unified NAM algorithm (right) for 16Z on 20 May 2020. The RH differences between the two algorithms (center) show the change in RH results in below freezing conditions from the NAM method. Graphics were produced by NCEP/EMC and COLA (Center for Ocean-Land-Atmosphere Studies).