Issued 5 Jul 2018
valid for weeks 1 and 2: 2 Jul – 16 Jul 2018
The Madden-Julian Oscillation (MJO) is currently weak but active over the western Indian Ocean. Over the first two weeks of July 2018, some models predict the eastward propagation of the weak MJO while other models project the MJO to become indiscernible as it moves over the Maritime Continent. Thus for the first fortnight of July 2018, the MJO is not expected to have a large impact on the region.
In terms of the weekly rainfall for the Southeast Asia region, the eastern Maritime Continent can expect above-average rainfall in the first week of July 2018. However, as the second week approaches, the wet weather conditions in the southern ASEAN region is expected to gradually ease due to a northward shift of the rain band associated with the strengthening of monsoon winds. Drier weather conditions can be expected over most parts of the southern ASEAN region in the second week of July.
In the northern ASEAN region, rainfall is expected to be above-average rainfall in the second week of July 2018, associated with a strengthening of mid-level westerly winds in the region. Areas around the Philippines, coasts of the Mekong sub-region and parts of the South China Sea have a higher likelihood of receiving above-average rainfall.
During this two-week period, the temperature over much of Southeast Asia is expected to be near-average. In parts of the Mekong sub-region, warmer temperatures are expected in week 1 than in week 2 where a gradually return to average conditions is expected.
The outlook is assessed for the region in general. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted.