TROPICAL CYCLONES IN THE SOUTH-WEST INDIAN-OCEAN - TRACK PREDICTION AND VERIFICATION 1989-91

The skill of the United Kingdom Meteorological Office weather prediction model in forecasting cyclone tracks in the south-west Indian Ocean is evaluated for the period 1989-91. The track predictions of the model are shown to be useful up to day 3. Mean track errors grow from an initialization value of 172 km to over 500 km by day 3. Cyclones which cross the highlands of Madagascar are not well handled by the model, recurving poleward while predictions maintain westward movement due to model resolution, the steep topography, and consequent entrainment of flow around Madagascar. The forecasting skill of the model is affected by the background flow patterns. Tropical westerlies increased in the 15-degrees-S zone in the first season and model errors were smaller.