Evaluation of cold-season precipitation forecasts generated by the hourly updated 3-km High Resolution Rapid Refresh (HRRR)

The NOAA Earth System Research Laboratory (ESRL) Global Systems Division (GSD) is developing and operating the High-Resolution Rapid Refresh (HRRR) numerical weather prediction model in support of the FAA's Aviation Weather Research Program (AWRP). Data generated by this model are currently used in CoSPA, an FAA sponsored automated storm forecasting system, to produce 0 – 8 hour forecasts of storm intensity and echo tops. Besides convective storms, we expect that the HRRR model will play an important role in NextGen for other aviation weather hazards, such as in-flight and ground icing, turbulence, ceiling and visibility.

As part of the Model Development and Enhancement (MD&E) effort, we have been investigating sensitivity of several aviation weather hazards to varied numerical weather prediction model configurations, emulating the HRRR and WRF Rapid Refresh (RR) models. This presentation will focus particularly on aspects of the HRRR model's ability to generate realistic precipitation types reaching the ground, which has important implications for prediction of ground deicing as well as in-flight icing conditions. We are analyzing 2009-2010 and 2010-2011 cold-season precipitation forecasts and assessing the precipitation types of the HRRR model output data using surface precipitation reports from CONUS-wide Automated Surface Observing System (ASOS) stations. We will present results depicting the skill of the HRRR model to predict the area coverage and location of precipitation intensity and type, including the timing of the rain-snow boundary passage, from data evaluated for two cold seasons. Possible forecast skill dependencies due to forecast lead time, storm characteristics (e.g., size, forcing mechanism), and location will also be investigated.

This research is in response to requirements and funding by the Federal Aviation Administration (FAA). The views expressed are those of the authors and do not necessarily represent the official policy or position of the FAA.