Using METplus to Asses Impactful Snow Events During the 2022-23 Winter Weather Experiment (WWE)

Winter storm events that produce regions of enhanced snowfall occur several times a year and have large impacts on the affected communities, yet continue to prove difficult to accurately forecast and evaluate. A collaborative effort between the National Center for Atmospheric Research (NCAR) and the Weather Prediction Center (WPC) as part of the Joint Technology Transfer Initiative (JTTI) effort, aims to integrate novel diagnostic capabilities aimed at investigating these high-impact events into the WPC model evaluation, and provide useful forecast products at WPC and other national centers using the enhanced Model Evaluation Tools (METplus). This project employs a number of developments and enhancements to the existing METplus infrastructure geared toward WPC’s operational needs. Specifically, the METplus software includes a number of resources well suited for diagnosing and analyzing heavy banded snowfall, and include feature relative, forecast consistency, multivariate mode, and difficulty index applications. The feature relative use-case employs the Method for Object-based Diagnostic Evaluation (MODE) Time Domain (MTD) tracked snow objects to provide object relative verification useful for identifying systematic biases in the surrounding environment. The forecast consistency tracks objects from MTD to measure the stability of a forecast across different forecast cycles. Multivariate MODE combines multiple variables to identify complex objects, such as snowbands and blizzard-like objects, and provides useful attribute information for comparison against observations, such as object size, intensity, and placement. Recently, multivariate MODE was enhanced to enable a more user-friendly and configurable workflow. The difficulty index uses an ensemble mean and spread to provide guidance on how difficult the forecast might be. For each of these use-cases, several events were investigated that produced enhanced snowfall over the Upper-Midwest and Northeast regions. This talk will highlight these capabilities from the JTTI project using cases from the 2022-23 winter season.