Intensity Guidance and Center Tracking for Landfalling Tropical Cyclones by VORTRAC

The Vortex Objective Radar Tracking and Circulation (VORTRAC) package combines a series of single Doppler radar algorithms to deduce landfalling tropical cyclone (TC) center, radius of maximum wind (RMW) and surface central pressure in real time from WSR-88D level II data and environmental reference pressure data from coastal stations and/or buoys. The VORTRAC V1.0 has been operational at the National Hurricane Center since 2008. Significant upgrades and automation to VORTRAC V2.0 have been implemented to address many operational related issues encountered in VORTRAC 1.0. VORTRAC 2.0 has been running continuously in real time during three TC landfalls.

Since very few landfalling TCs have occurred in the US after 2008, the characteristics and operational limits of VORTRAC can only be examined using historical landfalling TCs. A collection of 12 landfalling TCs between 2005-2011 was used for these purposes. These 12 TCs span a wide range of conditions (e.g., size, intensity, precipitation organization, range to the radar, etc) to test VORTRAC capabilities and limitations. The VORTRAC derived TC characteristics are compared with best track and Air Force Reconnaissance data when available. The results and statistics provide useful guidance to real-time operations including optimizing parameter selection and interpretation of the results.

This paper will present the upgrades implemented in VORTRAC 2.0, the real-time performance, and the statistical results from those 12 US landfalling TC cases.