Review of Regional Weather Conditions for Second Fortnight of August 2018
1. Review of Regional Weather Conditions for Second Fortnight of August 2018
1.1 Southwest Monsoon conditions prevailed in the second fortnight of August 2018. During the period, rainy weather persisted over most parts of the northern ASEAN region. For the northern parts of Myanmar, Lao PDR and Vietnam and parts of the Philippines, above-average rainfall was recorded.
1.2 In the southern ASEAN region, Sumatra and Kalimantan experienced drier conditions during the first half of the fortnight. This was followed by a gradual increase of shower activities in the latter half of the fortnight. The Java region remained generally dry throughout the period.
1.3 The daily average rainfall and the percentage normal of rainfall for the second fortnight of August 2018 are shown in Figure 1 and Figure 2.
1.4 Stronger-than-usual southwesterly winds prevailed over the northern ASEAN region. In the southern ASEAN region, there were no significant wind anomalies observed, and the prevailing winds generally blew from the southeast or southwest. Figure 3 shows the average and anomalous winds at 5000 feet.
1.6 The El-Southern Oscillation (ENSO) remained in the neutral state(neither El Niño nor La Niña), and other atmospheric indicators continued to show neutral conditions.
1.7 The Madden Julian Oscillation (MJO), which started in Phase 6, weakened and became non-discernible throughout the review period. The weakening of the MJO Phase 6 partly contributed to the cessation of drier conditions over the southern ASEAN region in the second fortnight of August 2018.