20 May 2003
Onset of this year's South China Sea Summer Monsoon to occur soon
Tropical cyclone 1B has made landfall over Myanmar. Therefore, as mentioned in the last discussion, onset of the South China Sea summer monsoon is likely to occur soon. Based on the ECMWF forecast charts, it appears that the subtropical high at 500 hPa still remains over the South China Sea on 22 May (Fig. 1) but will retreat out of it by 24 May (Fig. 2). At this time, the surface prog chart shows a low developing just off Hainan Island (Fig. 3). By 26 May, South China Sea is dominated by a low pressure area (Fig. 4). Thus, if the ECMWF forecasts are correct, onset of the South China Sea summer monsoon will likely occur around 24-26 May, which is slightly later than normal (around 15-20 May). This appears to be typical for the year after an El Niņo event (e.g. 1998).
Fig. 2.
