Meteorological Conditions in South East Asia: 26 April 1999

Meteorological Conditions in SouthEast Asia

26 April 1999

The Meteorological Service of Singapore reports on 25 April 1999 for the South East Asian region: “Cloudy conditions and scattered showers were observed over central and southern Sumatra. Isolated showers over Borneo islands”.

“Monitoring of satellite images and weather reports in the region shows that the region continues to be clear of significant forest fires and smoke haze. Only isolated and occasional hot spots and small smoke haze areas are being detected over central and northern parts of Sumatra”. “Latest reports and analyses have shown that the El Nino event which has brought the region severe dry condition since mid 1997 has weakened considerably. Areas of colder-than-normal sea surface temperature have appeared over parts of central Pacific Ocean, which when taken together with other information points to an increased chance of a La Nina event later in the year. In view of the above, rainfall in the region is expected to be near or above normal for the next few months. However, it should be noted that many parts of Indonesia (Kalimantan and parts of Sumatra) would be in their traditionally dry season in the next few months. As such, though extensive and prolonged smoke haze is unlikely for this period, occasional short periods (e.g. a few days) of slight to moderate haze in a more localized manner remain probable.

Fig.1. Regional Surface Winds and Haze/Hot Spot Map, 25 April 1999
(Source: Meteorological Service of Singapore)

The ASEAN Fire Weather Information System (ASFWIS) is a co-operation between ASEAN and the Canadian Forest Service. It provides maps describing the current fire weather situation in South East Asia. This system is based upon the Canadian Forest Fire Danger Rating System (CFFDRS) (for further infomation to the CFFDRS refer to ASFWIS). Studies have shown that the CFFDRS is applicable outside of Canada. Currently it is also used in a modified form in New Zealand (see References). In New Zealand the Fire Weather Indices Fine Fuel Moisture Code (FFMC) and the Initial Spread Index (ISI) represent the fire danger in the scrublands. The Duff Moisture Code (DMC) is also applicable in South East Asia, because it potentially describes the moisture state of the upper peat layers in peat and peat swamp forests. All three parameters may serve as a suitable indicator of forest fire danger in South East Asia.

According to the ASFWIS for 24 April 1999 these parameters show various fire weather conditions over South East Asia. The highest FFMC readings are recorded for northern Thailand, Sumatra and Java, with the FFMC values between 85 to 89. The DMC readings in the north-western part of Thailand were also increasing up to the highest rate of 91. Recent observations in neighbouring countries of South East Asia reveal that the fire danger situation in these countries is for the moment not so high.

Fig.2.,3. and 4. FFMC, ISI and DMC output of the ASFWIS

The Indonesian Meteorological Agency Badan Meteorologi dan Geofisika forecasts rainy and cloudy conditions for Indonesia with maximum temperatures between 28°C (Bandung), 30°C (Samarinda), 27°C (Ujung Pandang) and 31°C (Dili), 34°C (Palembang) and relative humidity ranging from 50% up to 99%.

The Forest Fire Prevention and Control Project (FFPCP) in Palembang (Sumatra) shows an updated of 22 April 1999 fire overview of Sumatra.

Fig.5. Fire Overview Map for 22 April 1999 of the FFPCP project in Palembang
(source: http://www.mdp.co.id/ffpcp/overview.htm)

No fire update information is currently provided by the Integrated Forest Fire Management (IFFM) project in Samarinda (East Kalimantan).

Summary: Although the current fire weather conditions do under normal conditions not favour extensive land clearing by fire or escaping wildfires in Indonesia, the consequences of the large wildfires of 1997-98 must been taken into consideration. These fires had caused extensive degradation of primary and secondary forests along with the spreading of “alang-alang” (Imperata cylindrica) grasslands. These grasslands facilitate the spread of uncontrolled fires over large areas.