Fire Weather Index: the skill provided by the European Centre for Medium-Range Weather Forecasts ensemble prediction system

Abstract

Abstract. In the framework of the EU Copernicus programme, the European Centre for Medium-Range Weather Forecasts (ECMWF) on behalf of the Joint Research Centre (JRC) is forecasting daily fire weather indices using its medium-range ensemble prediction system. The use of weather forecasts in place of local observations can extend early warnings by up to 1–2 weeks, allowing for greater proactive coordination of resource-sharing and mobilization within and across countries. Using 1 year of pre-operational service in 2017 and the Fire Weather Index (FWI), here we assess the capability of the system globally and analyse in detail three major events in Chile, Portugal and California. The analysis shows that the skill provided by the ensemble forecast system extends to more than 10 d when compared to the use of mean climate, making a case for extending the forecast range to the sub-seasonal to seasonal timescale. However, accurate FWI prediction does not translate into accuracy in the forecast of fire activity globally. Indeed, when all fires detected in 2017 are considered, including agricultural- and human-induced burning, high FWI values only occur in 50 % of the cases and are limited to the Boreal regions. Nevertheless for very large events which were driven by weather conditions, FWI forecasts provide advance warning that could be instrumental in setting up management and containment strategies.

Brief Communication: Key papers of 20 years in Natural Hazards and Earth System Sciences

“…By systematically evaluating the ECMWF ensemble forecast system performance to reproduce fire weather index (FWI) from observing stations at the global scale, the authors demonstrate the capacity of this ensemble approach to be reasonably accurate up to 10 days ahead, especially for some of the largest fires that took place in 2017, namely in Chile and Portugal. Their results confirm that early warning could be extended by up to 1-2 weeks by using advanced numerical weather models, allowing for better coordination of resourcesharing and mobilization within and across countries (Di Giuseppe et al, 2020).…”

“…heatwaves, floods or tropical cyclones) reached a fairly mature standard, however, the forecast of wildfire prone conditions still lags behind with fire danger indicators mostly relying on environmental monitoring. In 2020, a study led by Francesca Di Giuseppe (Di Giuseppe et al, 2020) published in NHESS suggested extending fire danger warnings with the use of the most advanced weather forecast model available, i.e.…”

Global warming is shifting the relationships between fire weather and realized fire-induced CO2 emissions in Europe

“…Crucially, studies on future fire risk projections indicate that fire impacts in Southern Europe should experience a turning point in the near future, shifting from currently decreasing trends to a high impact trajectory 8 , 9 . Overall, due to the large impacts of fire on ecosystem services and multiple social and economic assets, there is an urgent need for more detailed quantitative studies analyzing the changing relationships between fire weather and realized impacts in continental Europe 10 , 11 .…”

“…However, its simplicity of implementation has made it a popular choice in many countries, and it has been shown to perform reasonably well in global analyses and in ecosystems very dissimilar to the boreal forest 13 – 17 . The FWI system is also the rating system for fire monitoring adopted in many European countries and a principal component of the Copernicus Emergency Management Service CEMS 11 . All the components of the FWI system only rely on weather forcings, and neither information on the vegetation status nor on the ignition are taken into account.…”

Some Challenges for Forest Fire Risk Predictions in the 21st Century

“…Traditional approaches for forecasting seasonal changes in fire weather relied on developing fire weather and danger indices that, often, seek to estimate fuel moisture and potential fire spread depending on past meteorological conditions. These indices have shown mixed success in predicting fire danger [29,30], and they have not been exempt from criticism [31]. Developing an early warning system for catastrophic fire, which predicts when and where critical wildfires will occur, as well as educating the populace on how to interpret these predictions, has become an increasing necessity [3].…”