Meteorological Conditions in South East Asia: 12 March 1999

Meteorological Conditions in SouthEast Asia

12 March 1999

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), 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.

Extreme Fire Danger in Northern Thailand
High Fire Danger in Vietnam
High Fire Danger for Grasslands in Northeastern Sumatera

According to the ASFWIS for 11 March 1999 these parameters show various fire weather conditions over South East Asia.  The highest FFMC readings are recorded for northern Thailand and Vietnam, with the FFMC values over 93. Taking the DMC readings into account the fire danger ratings in northern Thailand and in parts of Vietnam indicates extreme fire danger for 11 March 1999. Recent surveys in neighbouring countries Lao, Cambodia, and Myanmar reveal that the fire danger situation in these countries is similarly high. Due to wet conditions the fire danger in Indonesia is generally low. The readings in Northeastern Sumatera near Jambi indicate high fire danger for grasslands in parts of Sumatera. The ISI readings are over 16, this indicates high fire danger rating in grasslands. The ISI which is comprised of the FFMC and wind speed serves as the indicator for fire danger in grasslands. (Since the ISI is highly dependent on windspeed as input it can track down rapid fire weather changes and is reacting faster than the FFMC and DMC Index.)

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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 the Indonesian Meteorological Agency Badan Meteorologi dan Geofisika which forecasts rainy and cloudy conditions for Indonesia with maximum temperatures between 27°C (Bandung), 32°C (Samarinda), 31°C (Ujung Pandang) and 32°C (Dili), 30°C (Palembang) and relative humidity ranging from 58% up to 97%. In the region in which high fire danger is predicted for grasslands (Jambi) the weather forecast predicts temperatures between 24°C and 32°C with relative humidity ranging from 65-87% and rain. The general forecast for Indonesia is rainy and cloudy.

The Meteorological Service of Singapore reports on 11 March 1999 for the South East Asian region: “No hot spots detected the region remains generally free of smoke haze”. “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”. 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”.

No fire update information is currently provided by the Integrated Forest Fire Management (IFFM) project in Samarinda (East Kalimantan)  and the Forest Fire Prevention and Control Project (FFPCP) in Palembang (Sumatera).

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.

See also the IFFN Country Notes.

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