Review of Regional Weather Conditions for Second Fortnight of June 2019

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1. Review of Regional Weather Conditions for Second Fortnight of June 2019

1.1 In the second fortnight of June 2019, moderate to strong southwesterly or westerly winds prevailed over the northern ASEAN region. In the southern ASEAN region, winds continued to blow from the southeast or southwest. No significant wind anomalies were observed during this period.


Figure 1: 5000 ft average winds (left) and anomalies (right) for 16 – 30 June 2019. (Source: JMA)

1.2 In the second half of June 2019, the monsoon rain band brought widespread showers over parts of the northern ASEAN region, in particular over the coastal regions. In the southern ASEAN region, most of the rain/showers fell over the equatorial region including Malaysia, Sumatra and Kalimantan. Over Java and the southern parts of Sumatra and Kalimantan, dry weather prevailed and rainfall was below-average.


Figure 2: Daily average rainfall for the ASEAN region in the second fortnight of June 2019. (Source: JAXA Global Satellite Mapping of Precipitation)

Figure 3: Percent of average rainfall for 16 – 30 June 2019. The rainfall data may be less representative for areas with a less dense rainfall network. (Source: IRI NOAA/NCEP CPC Unified Precipitation Analyses)

1.3 In the early half of the fortnight, the Madden-Julian Oscillation (MJO) was in the Maritime Continent but weakened in the later part of the fortnight. There were no clear MJO signals during the period as shown in Figure 4.

1.4 The El-Nino Southern Oscillation (ENSO) is currently in the neutral state. Sea-surface temperature (SST) anomalies remained slightly warmer than average in the central eastern Pacific.

Figure 4: The MJO phase diagram for June 2019 (green). The diagram illustrates the movement of the MJO through different phases, which correspond to different locations along the equator. The distance of the index from the centre of the diagram is correlated with the strength of MJO. When the index falls within the circle, the MJO is generally considered weak or indiscernible. (Source: Bureau of Meteorology)