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The fire danger forecast module of GWIS provides forecast maps from 1 to 9 days on the levels of fire danger by weather. These estimates are based on numerical weather predictions (Van Wagner and Pickett, 1985; Copernicus Emergency Management Service, 2019). In 2019, due to the interest of countries to compare the performance of the Fire Weather Index (FWI) with other relevant fire danger indices, the Australian McArthur Forest Fire Danger Index (MARK-5), the Keetch-Byram Drought Index (KBDI) and the National Fire Danger Rating System (NFDRS) have been made available through GWIS.
GWIS operates using meteorological forecast data received daily from the European Centre for Medium-Range Weather Forecast (ECMWF).
Fire danger is mapped in 6 classes (very low, low, medium, high, very high and extreme) with a spatial resolution of about 8 km (ECMWF data). At the moment, the fire danger classes are the same for all countries, and maps show a harmonised view of the spatial distribution of fire danger level.
However, given the different climatic conditions at the global level, GWIS publishes two indicators that provide information on the local/temporal variability of the FWI values as compared to a historical time series of approximately 30 years. Those products are the ranking, which provides percentiles of occurrence of the values, and the anomaly, computed as a standard deviation from the historical mean values. These indices are available in the "index" pull-down menu.
The following are the FWI values used as thresholds of the fire danger classes in the map:
| Fire Danger Classes | FWI | FFMC | DMC | DC | ISI | BUI |
|---|---|---|---|---|---|---|
| Low | < 11.2 | < 82.7 | < 15.7 | < 256.1 | < 3.2 | < 24.2 |
| Moderate | 11.2 - 21.3 | 82.7 - 86.1 | 15.7 - 27.9 | 256.1 - 334.1 | 3.2 - 5.0 | 24.2 - 40.7 |
| High | 21.3 - 38.0 | 86.1 - 89.2 | 27.9 - 53.1 | 334.1 - 450.6 | 5.0 - 7.5 | 40.7 - 73.3 |
| Very High | 38.0 - 50.0 | 89.2 - 93.0 | 53.1 - 83.6 | 450.6 - 600.0 | 7.5 - 13.4 | 73.3 - 133.1 |
| Extreme | 50.0 - 70.0 | 93.0 - 96.0 | 83.6 - 160.7 | 600.0 - 749.4 | 13.4 - 26.8 | 133.1 - 193.1 |
| Very Extreme | > 70.0 | > 96.0 | > 160.7 | > 749.4 | > 26.8 | > 193.1 |
A data-transformation model of the FWI is also used to provide a measure of fire control difficulty: the Daily Severity Rating (DSR: Van Wagner, C.E., Pickett, T.L., 1985). Its average of daily estimates over a week is called Weekly Severity Rating (WSR).
References
Van Wagner, C.E., Pickett, T.L., 1985. Equations and FORTRAN program for the Canadian Forest Fire Weather Index System. Forestry Technical Report. Canadian Forestry Service, Ottawa, Canada. https://purl.org/INRMM-MiD/c-14026112
Copernicus Emergency Management Service, 2019. Fire danger indices historical data from the Copernicus Emergency Management Service. In: Copernicus Climate Change Service (C3S) Climate Data Store (CDS). https://doi.org/10.24381/cds.0e89c522