The NCEP Operational Global Cyclone Tracking and Verification System

Guang Ping Lou


The regional tropical and extratropical cyclone tracking system has been in existence for several years in the NCEP operational domain. The search regions are mainly confined in the North America and adjacent oceanic basins. Moreover there is no operational verification mechanism that can give modelers/forecasters information about the forecast tracks accuracy and biases. The difficulty lies on the fact that there are no observed extratropical cyclone tracks available as the verifying “truth”, as in the tropical storm cases, the “best tracks” are issued by the TPC in real time.

The EMC Mesoscale Modeling Branch embarked on an undertaking that expands the tracker to global in scope and at the same time, devised a real time verification mechanism that displays forecast track position errors and biases. The scheme takes model analysis tracks as the “truth”. It is fully automatic and operational. The system is also used to compute the tracks climate statistics. Details of algorithm and steps will be presented and discussed.

Preliminary results show that the forecast cyclone track position errors in several models mainly come from north-south displacement. East-west track forecasts are more accurate.