An Objective Technique for Estimating Present Tropical Cyclone Locations

Abstract

A technique is developed and tested for estimating objectively the location of a tropical cyclone from a variety of fixes. The western North Pacific climatology and persistence (WPCLPR) track forecast technique is used to generate a potential track from each fix. A tentative warning position is interpolated from a smooth curve that is fit to the future and past positions. When multiple fixes are available, weighting functions are applied to account for the expected accuracy and the timeliness of each fix. Several empirical factors are determined by sensitivity tests with a dependent sample of eight storms that includes 226 warning positions. An independent sample of 22 storms with 610 warning positions is used to demonstrate that the accuracy of the objective technique is not significantly different from the official Joint Typhoon Warning Center (JTWC) warning positions during 1981–83. The short-term track forecast accuracy with WPCLPR is essentially the same whether the JTWC or the objective warning positions are used. Thus, the objective technique provides an efficient tool for the forecaster to use in establishing the present location of the tropical cyclone.