Sensitivity to initial conditions on the simulation of extratropical cyclone ‘Gong’ formed over North Atlantic

The role of initial conditions (ICs) in the simulation of severe winter storm ‘Gong’ formed over North Atlantic is studied. The life cycle of Gong started at 1800 UTC of 16–0600 UTC of 22 January, 2013, with CSLP of 972 hPa. The gusty wind (~33 ms−1) and torrential rainfall of ~90 mm d−1 recorded over several major cities of the Iberian peninsula. Five numerical experiments were performed with the WRF model by initializing at 0600 UTC of 16, 1800 UTC of 16, 0600 UTC of 17, 1800 UTC of 17, and 0600 UTC of 18 January, 2013. Our results suggest that significant differences are seen among the experiments, particularly with the ICs of 0600 UTC 17 January, 2013, which represent the quick movement of Gong with a slight underestimation of intensity. The experiment with IC 0600 UTC on 18 January, 2013 produced the best simulation as compared to the observations. The simulated track, intensity, wind flow, and rainfall were well agreeing with the observations. The 12-h average track errors were ranging from 95 to 332 km with 24-, 36-, 48-, 60-, and 72-h lead time. The Q-vectors of Gong with the WRF model with 24-h lead time produced minimum errors.