2017−18 HRRRv3/RAPv4 Cloud and Wind Modeling/Assimilation Improvements toward Increased Renewable Penetration

Renewable energy applications are a major driver for HRRR/RAP weather model development. The hourly updated 3km HRRR and 13km RAP models (over a wider North American domain) are the backbone for NOAA’s hourly-updated model guidance.

Major changes to the cloud assimilation and boundary-layer modeling, driven in part by WFIP2, are central to a HRRR/RAP upgrade planned for implementation at NCEP in February 2018. Wind and solar forecast accuracy are closely tied through accuracy of boundary-layer evolution. The most significant changes to cloud assimilation in 5 years allow improved cloud retention from observations. Improved treatment of thermal plumes in the MYNN boundary-layer scheme (developed by GSD – Olson and Kenyon) and more accurate land-surface treatment are central to improved wind and subgrid-scale cloud forecasts. Tests also for WRF-ARW changes for the vertical coordinate and horizontal diffusion show further benefit, and these changes are also included in the HRRRv3/RAPv4 package.

These changes will be summarized appropriately for the AMS energy-new-economy audience – they are a strong step forward for energy guidance but also of much benefit to other short-range forecast user groups including aviation and severe weather communities.