Galarneau, Thomas and Christopher Davis, National
Center for Atmospheric Research
This presentation
reports on the development of a diagnostic approach that can be used to examine
the sources of numerical model forecast error that contribute to degraded
tropical cyclone (TC) motion forecasts. Results from an analysis of 24-h
forecasts from the 2011 and 2012 versions of the Advanced Hurricane Weather
Research and Forecasting model for TCs Earl (2010) and Fiona (2010) show that
forecast motion errors are dominated by errors in the environment wind field.
Contributions from errors in the vertical depth of the vortex and near-vortex
asymmetries are occasionally large and are interpreted using Òvorticity
thinking.Ó The utility of this new diagnostic equation is that it can be used
to assess TC motion forecasts from any numerical modeling system.