Methods for Objective Evaluation of Near-Surface Wind Structure Forecasts from Dynamical Models

Differences among tropical cyclones in the distribution of near-surface winds can contribute to wide variations in impacts such as wind damage, storm surge and rainfall. Forecasts from dynamical models provide guidance on the structure of the surface wind field, and so it is imperative to build a comprehensive set of tools for objectively evaluating surface wind structure forecasts. In this poster, we propose a set of methods for objectively verifying such near-surface TC wind structure forecasts.

The proposed methods extend beyond the evaluation of standard 34-, 50- and 64-knot wind radii. Here, we verify the model-predicted surface wind values that have been azimuthally averaged at discrete radii surrounding 45-degree azimuths in each storm quadrant. This method provides a continuous wind profile for each model in each quadrant. A technique developed by Chen et al. (2023) that derives coefficients describing the differences in the shapes of the wind profiles between forecasts and observations will be applied to storms in this study. In addition, forecasts of near-surface integrated kinetic energy (Powell and Reinhold 2007) will be compared to observations. Another method evaluates the statistical distribution of near-surface winds in each storm quadrant.

The models that will be evaluated include the two new operational NOAA Hurricane Analysis and Forecast System (HAFS) models that were implemented in 2023, HAFS-A and HAFS-B. The operational NOAA Global Forecast System (GFS) will also be evaluated. Additionally, two experimental configurations of the System for High-resolution prediction on Earth-to-Local Domains (SHiELD) developed at the NOAA Geophysical Fluid Dynamics Laboratory (GFDL) will be evaluated. These include the global uniform 13km resolution SHiELD and the two-way nested T-SHiELD configuration that places a 3-km nest over the Atlantic Basin.

In the poster, we will describe the techniques used and provide examples of these methods applied to storms from the 2023 Atlantic hurricane season.

References

Chen, J., K. Gao, L. Harris, T. Marchok, L. Zhou, and M.J. Morin, August 2023: A new framework for evaluating model simulated inland tropical cyclone wind fields. Geophysical Research Letters, 50(16), DOI:10.1029/2023GL104587.

Powell, M. D., and T. A. Reinhold, 2007: Tropical Cyclone Destructive Potential by Integrated Kinetic Energy. Bull. Amer. Meteor. Soc., 88, 513–526, https://doi.org/10.1175/BAMS-88-4-513.