An alternate method for extracting wind structure guidance from numerical models

In this paper, we examine an alternate method of using output from dynamical models for tropical cyclone wind structure guidance. Currently, two different versions of a climatology- based wind radii CLIPER model provide guidance to the National Hurricane Center on the radii of 34-, 50- and 64-knot winds. In addition, wind radii guidance from various dynamical models is provided via output from NCEP's tropical cyclone tracker. The problem with guidance from the dynamical models is that these models are often unable to produce winds that match the observed winds at the reporting thresholds of 34, 50 and 64 knots. In such cases, the forecasters are left without updated guidance from the dynamical models.

In the current work, rather than search the model output for near-surface winds that exceed a certain threshold and then reporting that distance, we instead evaluate and report the model winds at specified radii from the storm center. In this way, we can provide wind structure guidance from a model for 100% of the cases for which that model produces a track forecast.

The poster will describe the methods used, as well as an evaluation of these methods for selected 2005 Atlantic storms for the GFDL, GFS, UKMET, ECMWF, NOGAPS and NCEP/NAM models.