Meteorological Conditions in South East Asia: 24 November 1998

Meteorological Conditions in SouthEast Asia

24 November 1998

The ASEAN Fire Weather Information System (ASFWIS) 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, and is currently tested on an experimental basis. 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 November 1998 these parameters are slightly increasing almost all over South East Asia.  The highest FFMC readings are recorded for northern Vietnam, with the FFMC ranging between 90-92. Due to changed weather conditions, the ISI readings  in northern Thailand and northern Vietnam decreased over the last days.

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Fig.1. FFMC output of the ASFWIS

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 Fig.2. DMC output of the ASFWIS

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Fig.3. ISI output of the ASFWIS

These findings are consistent with the current weather reports from Badan Meteorologi dan Geofisika ( which records rainy and cloudy conditions for Indonesia with temperatures between 19 ° C (Bandung) and 35° C (Samarinda) with relative humidity ranging from 50% up to 97%. In Central Sumatera the weather forecast for the hotspot area (Medan) is minimum temperature 23  °C and maximum temperature 32 °C with relative humidity ranging from 60-97 %. The forecast predicts rain for tomorrow. In  Pekanbaru temperature range from 23-34 °C with relative humidity from 50-95%, the forecast is cloudy. Special caution in this area is necessary. The general forecast for whole Indonesia is cloudy and rainy.

The Meteorological Service of Singapore ( reports for the South East Asian region “some isolated hot spots with smoke plumes were observed over Central Sumatera. The region is mostly free of smoke haze”. The Meteorological Service states for the near future that: “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 Sumatera) would be in their traditional 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 localised manner remain probable”.

The FFPCP project in Palembang ( records  90 hotspots on 23 November 1998 with a detection threshold of 320 K in Sumatera. An increase of burning activities can be observed compared to the last posted overview map of 18 November 1998 (27 hotspots). The hotspots are  especially accumulated in the provinces of Sumut and Riau. The burning activities detected by the NOAA AVHRR sensor are land clearing fires. Attention must be given in these provinces of Sumatera to prevent the escape of these land-use fires into surrounding vegetation.

Summary: Although the current fire weather conditions do under normal conditions not favour extensive land clearing by fire or escaping wildfires, 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. It can be predicted that in November-December with only moderate fire danger new vegetation fires will occur.

See also the IFFN Country Notes.

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