RAMMB: TC Extended Best Track Dataset

The Tropical Cyclone Extended Best Track Dataset

May 28th, 2009 Update: 2008 Atlantic and East Pacific storm cases added.

The National Hurricane Center (NHC) maintains a climatology of all Atlantic tropical cyclones since 1851, referred to as HURDAT. For each storm HURDAT contains estimates of the latitude, longitude, 1-minute maximum sustained surface winds, minimum sea-level pressure, and an indicator of whether the system was purely tropical, subtropical or extra-tropical at 6-hour intervals. A limitation of HURDAT is that it does not contain any information about storm structure. The “extended” best track file was created by supplementing HURDAT with additional storm parameters determined by NHC. The additional parameters include the following:

1. Maximum radial extent of 34, 50 and 64 kt wind in four quadrants
2. Radius of maximum wind
3. Eye diameter if available
4. Pressure and radius of the outer closed isobar

The extended best track for the Atlantic back to 1988 is available from

ftp://rammftp.cira.colostate.edu/demaria/ebtrk/ebtrk_atlc.txt

The extended best track for the eastern North Pacific back to 2001 is available from

ftp://rammftp.cira.colostate.edu/demaria/ebtrk/ebtrk_epac.txt

The extended best track documentation is available from

ftp://rammftp.cira.colostate.edu/demaria/ebtrk/ebtrk_readme.txt

The readme file describes the units and format of the file, which was designed so it can easily be imported into a spreadsheet. The original development of the extended best was supported by the Risk Prediction Initiative in Bermuda and continued support is provided by the NESDIS Center for Statellite Applications and Research (StAR). The file is usually updated with data from the previous year in late February or early March once NHC finalizes the best track data. The additional wind structure parameters are estimated in real time during the NHC forecast process. Since 2004, NHC also produces post-storm best track estimates of the wind radii. The extended best track includes the best track radii since 2004 and operational radii estimates before 2004.

Sample NHC wind swath product based on their wind radii estimates.

A reference for the extended best track is

Demuth, J., M. DeMaria, and J.A. Knaff, 2006: Improvement of advanced microwave sounder unit tropical cyclone intensity and size estimation algorithms. J. Appl. Meteor., 45, 1573-1581.

Project Team:

Mark DeMaria
John Knaff