The Analysis of Abrupt Northward Turning of Typhoon Megi(1013) Using TIGGE Data

Typhoon Megi (15W) was the most powerful and longest lived TCs over the western North Pacific (WNP) and South China Sea (SCS) in 2010. It experienced suddenly northward turning when Megi entered SCS. Most of the numerical model failed to catch the abrupt turning of Megi.

The charateristics of the environmental flow and the vortex of typhoon “MEGI” related to the sudden changing of the track are analyzed using the data provided by ECMWF ensemble prediction system with initial time at 12UTC 16 Oct.. This system consists of 51 members. The analyses are carried out for the two groups: one group consists of 5 members which predicted the abrupt northward turning of Megi (named as NT group) successfully and the other group consists of 5 members which predicted the westward moving of Megi (named as W group). The results show that the asymmetric structures and the weaker low pressure to the south of “Megi” at the initial time are helpful to the stronger intensity and bigger size of “Megi” in the later stage and this accelerates the breaking of the subtropical high and the southward development of the westerly trough; The subtropical high to the north of “Megi” in the NT group is weaker during the earlier stage of the forecast and breaks into two parts also earlier compared to the W group; The westerly trough is stronger in the later stage of the NT group and this is very important to the northward turning of “Megi”.