Abstract 185

Abstract ID: 185

PISSARO: a collaborative and user-oriented project on the monthly forecasting of extreme events in the southwest Indian Ocean

Lead Author: Sylvie Malardel
Laboratoire de l’Atmosphère et des Cyclones (LACy), France (La Réunion)

Keywords: subseasonal forecasting, tropical cyclone, heavy tropical rainfall, ITCZ, Southwest Indian Ocean

Abstract: The PISSARO project focuses on atmospheric and oceanic forecasting at the subseasonal scale for applications over the southwest Indian Ocean basin (SWIO). It is a collaborative academic research project, developed and conducted in partnership with stakeholders from Reunion and Seychelles and a panel of scientific experts in tropical forecasting.
The different territories of the SWIO are subject to extreme events such as tropical cyclones and intense tropical rainfall. These phenomena are strongly influenced by larger scale atmospheric and oceanic patterns (ENSO, IOD, SIOD, MJO, tropical waves…) which have some predictability at the subseasonal scale. During the tropical cyclone season, the low frequency variability of the atmosphere and the ocean, the MJO activity and the tropical waves and their possible interaction with the TC activity are summarized in an automatic weekly outlook posted on the PISSARO web site. Once a month, a team of experts expertise this information which is then further discussed with the PISSARO partners in a briefing led by the experts.
We have also exploited the IFS monthly forecast ensemble for the development of future S2S-derived forecast products to provide probabilities of TC trajectory scenarios, rainfall anomalies and to follow the ITCZ migration in the southwest Indian Ocean. The products which have been designed and calibrated with the S2S data are now tested in real time during the 2023 austral summer by the forecasters of the Seychelles Meteorological Authority and at the RSMC-Tropical Cyclones of La Réunion. At the end of the TC season, these prototypes will be evaluated and the best products will be selected for an operational implementation. Several examples of these products, together with the feedback from the users will be presented at this workshop.

H. Vérèmes (LACy), F. Bonnardot (Direction Inter Régionale de Météo-France dans l’Océan Indien, DIROI), P. Peyrillé (Centre National de Recherches Météorologiques, CNRM), S. Langlade (DIROI), T. Lefort (Lefort Weather Consulting), L. Labbé (DIROI), A. Cachard (LACy) and Q.-P. Duong (LACy).