Investigation of Critical Fire Weather Pattern - Case Study

Atmospheric blocking is a large-scale phenomenon occurs in the mid-latitudes to high latitudes in the troposphere, leading to severe and persistent weather anomalies such as heat waves, cold spells, and extreme dry conditions with large fires and floods. A series of huge wildfires occurred in some regions in the south and north of Lebanon in mid - October 2019, in which the region witnessed a heat wave with high averages of minimum and maximum temperatures, accompanied with dry weather conditions and high speed winds. This situation is attributed to the domination of high blocking pattern (strong Ridge) over eastern Mediterranean region for many days leading to fire outbreak, and the active wind participated in extending the fires to forests and green lands. The present research focuses on Chouf district, in Mount Lebanon Governorate as the study area in which it witnessed the most severe wildfire outbreak, based on ERA5 atmospheric reanalysis data at the surface and upper levels for the period (13-16) of October 2019. It was found that the existence of atmospheric blocking system over the region for many days was the main factor in creating the dry and extremely hot weather, and the ridge outbreak caused the ignition of fire, reinforcing the wildfire intensity and amplifying the fire patches to other regions.