Revision of JMA’s Early Stage Dvorak Analysis and Its Use to Analyze Tropical Cyclones in the Early Developing Stage

This report follows Kishimoto et al. (2007). The Japan Meteorological Agency (JMA) conducted verification of the behaviors of past tropical cyclones (TCs) for the purpose of developing the diagnosis of T-number 0.5 (T0.5). The results indicate that T0.5 diagnosis is valid for satellite image analysis for TCs in the early developing stage (early stage Dvorak analysis: EDA). Organized convective cloud systems (OCCSs) diagnosed as T0.0 or T0.5 can be recognized as follows: Most OCCSs are not yet determined as tropical depressions (TDs) when they are first diagnosed as T0.0. OCCSs are likely to be determined as TDs when they are first diagnosed as T0.5. In summer 2007, based on the above results and Kishimoto et al. (2007), JMA revised EDA. The main part of this revision involved the addition of T0.5 diagnosis to the former EDA, which consisted of OCCS detection, T1.0 diagnosis and T1.5/2.0 diagnosis. In addition, JMA revised the criteria for determining the TC grade using EDA results. Analysis of TCs in the early developing stage using the revised EDA is explained through the example of the TD that became USAGI (0705).