Evaluation of Boundary Layer Structure in NWP Models

NOAA's operational High Resolution Rapid Refresh (HRRR) model is run at convection-permitting (3 km) horizontal resolution and utilizes the Mellor–Yamada–Nakanishi–Niino level 2.5 (MYNN2) PBL scheme. This is a state-of-the-art treatment that has been substantially upgraded and expanded in recent years. HRRR forecasts of boundary layer wind, temperature, and specific humidity are being evaluated using 60 high-resolution radiosondes across the contiguous US (CONUS) that can provide roughly 5 m vertical resolution near the surface. Challenges in employing this underutilized resource have been mitigated or overcome and the spatially- and temporally-averaged composites are revealing shortcomings in the forecasts that can be addressed with further improvements to the scheme. Along with evaluation, some improvements will be proposed and tested.