|From 1 June 2004, JMA narrowed probability circles* for the tropical cyclone
(TC) track forecast. This improvement is based on the verification results
of the recent TC track forecasts.
||A circular range into which the tropical cyclone is expected to move with
the probability of 70% at each validation time
The verification of our forecasts from 2001 to 2003 indicated the feasibility
of reduction in the radii of the probability circles by about 10% on an
average compared to the previous ones, in particular 25% for TCs with the
movement speed of more than 15kt (Fig.).
The narrowed provabiliy circle is expected to allow disaster prevention
activities to be more effectively coordinated.
1 June 2004
||Fig.: Example of the improvement of the TC track forecast
This shows a comparison of the new probability circle with the old one
in the case of a track forecast of TY ETAU (0310) issued at 12UTC 6 August
2003. The red solid circles indicate new probability circles, and the blue
dashed ones describe old probability circles.