Meaningful Evaluation Strategies for Numerical Model Forecasts using MET 

Tara Jensen
July 29th 3:45 pm in room 2155

The Developmental Testbed Center (DTC) serves as a bridge between research and operations for numerical weather forecasts. Thus, the DTC staff have developed and incorporated a number of strategies for doing meaningful evaluations of these forecasts to ensure that the weather community can trust that real and significant improvements are realized prior to operational implementation. Use of appropriate metrics; accurate estimates of uncertainty; consistent, independent observations; and large, representative samples are essential elements of a meaningful evaluation. Spatial, temporal, and conditional analyses should be incorporated wherever appropriate.

Numerous new methods have been proposed to improve quantification and diagnoses of forecast performance with use of spatial, probabilistic, uncertainty and ensemble information. The complexity of these methods makes verification software development difficult and impractical for many users. Further, verification results using the same methods may not be comparable when different software is used. To address these issues, community verification software has been developed through a joint partnership between the Developmental Testbed Center (DTC) and the Research Applications Laboratory (RAL) at the National Center for Atmospheric Research (NCAR) to provide a consistent and complete set of verification tools. This software package, the Model Evaluation Tools (MET;, is free, configurable, and supported by the DTC and has been adapted to work with an ever-increasing variety of forecast and observation types. New verification methods and dataset options are added each year, with input from the community and from developments in the published literature.

MET allows users to verify forecasts via traditional, neighborhood, and object-based methods. To account for the uncertainty associated with these measures, methods for estimating confidence intervals for the verification statistics are an integral part of MET. The latest release is set for August 2014 and will include many enhancements for users. MET will now accept data in NetCDF-CF compliant format and will have an expanded set of continuous and categorical statistics. The tropical cyclone verification capabilities have also been enhanced.  Autoconf has been added to make compilation easier and output file sizes have been reduced drastically to assist operational users. DTC has also developed a database and display system for internal use called METViewer.  The prototype was recently reworked for enchanced utility and METViewer version 1.0 will be ready for friendly beta-testers as well.

This presentation will provide an overview of verification methods included in MET and METViewer to highlight their capabilities for both operational and diagnostic use.  Examples of evaluations from DTC projects will be presented to demonstrate the existing and up-coming verification capabilities.