Extratropical Cyclones Leading to Extreme Weather Events in the FV3GFS Retrospectives

Extratropical cyclones (ECs) play a major role in determining day-to-day weather conditions in the middle latitudes during the cool season. Particularly strong ECs can have considerable socioeconomic impacts on the regions they traverse due to their frequent association with damaging winds and heavy precipitation. A subset of particularly strong ECs that form over and traverse densely populated regions have the potential to lead to extreme weather events (EWEs), defined as a category of high-impact weather events that are societally disruptive, geographically widespread, exceptionally prolonged, and climatologically infrequent. Successfully forecasting the track and intensity of ECs leading to EWEs, as well as the areal extent of their associated precipitation and wind fields, remains a challenge for local forecast offices and national centers tasked with their prediction.

This presentation investigates forecasts of ECs leading to EWEs over North America included in the FV3GFS retrospectives produced by NCEP/Environmental Modeling Center (EMC) in order to evaluate the FV3GFS prior to its operational implementation in early 2019. The operational implementation of the FV3GFS is the first major step toward upgrading the current operational GFS to run as a unified, fully-coupled, Next Generation Global Prediction System (NGGPS). Specifically, the Model Evaluation Group at NCEP/EMC will examine and compare current operational GFS and FV3GFS retrospective forecasts of ECs leading to EWEs over North America that occurred during 2015–2018. Differences in the track and intensity of ECs leading to EWEs, as well as a comparison of the areal extent of their associated precipitation and wind fields, will be presented. Noteworthy improvements and/or shortcomings associated with FV3GFS retrospective forecasts of ECs leading to EWEs over North America will be discussed.