Prediction of the August 2018 heavy rainfall events over Kerala with high-resolution NWP models

Abstract

The southern Indian state of Kerala experienced exceptionally high rainfall during August 2018, which led to devastating floods in many parts of the state. Prediction and early warning of severe weather events in vulnerable areas is crucial for disaster management agencies in order to protect life and property. In recent years, state-of-the-art numerical weather prediction (NWP) models have been used operationally to predict rainfall over different spatial and temporal scales. In the present paper, predictions based on the National Centre for Medium Range Weather Forecasting (NCMRWF) models (NCUM, NCUM-R and NEPS) are assessed over Kerala to demonstrate the capabilities of high-resolution models. It is found that the deterministic NWP model (NCUM and NCUM-R) forecasts are accurate at shorter lead times (up to Day 3) mainly in terms of timing and, to some extent, intensity. At higher lead times (beyond Day 3), the ensemble-based probabilistic forecasts are useful and actionable.