Zachery Taylor Law, James B Elsner

Climate models show rainy seasons getting rainier and dry seasons getting drier due to global warming from increasing greenhouse gases but local changes in drying, the understanding of which is important for mitigation efforts, will not necessarily match the global response. Here long-term weather observations from the Weather Service Office in Tallahassee are used to examine soil moisture deficits and to quantify the extent to which these deficits are related to wildfire occurrences in the nearby Apalachicola National Forest (ANF). Results show a 20% increase in the average rate of wildfires from May through July for every one cm increase in soil moisture deficit during April. The out-of-sample correlation between the observed number and the predicted rate of wildfires is +.57. Tracking daily soil moisture deficits prior to the start of the wildfire season provides a real-time update on developing drought conditions that have had an impact on wildfire activity in the ANF during the weeks to months ahead. Further, long-term upward trends in soil dryness are identified with the most pronounced changes occurring during the driest months. Taken together these findings, and assuming a continuation of the chronic drying, indicate a greater future risk of fires in the ANF.