Description

Alaska’s central and eastern interior (CEI), including the greater Tanana Valley and Yukon Flats, has consistently been the most fire prone area of the state during the last two decades. Toward operational and research applications, several surface fire weather indicators have been developed, such as the Buildup Index (BUI), and linked to CEI fire ignition, size, and spread. Beyond few analyses involving extreme fire years, studies have seldom examined the role of regional atmospheric circulation in modulating the region’s fire weather conditions through time. Moreover, modern forecast models’ skill in predicting such fire weather conditions is relatively low beyond a lead time of 10-14 days. This shortcoming creates numerous challenges for the fire managers attempting to mobilize resources for potential impacts. More complete understanding of atmospheric patterns and processes and their statistical linkages with fire weather at long-range weather-to-climate scales could thus be broadly useful to the fire community.

In this webinar, we will discuss historical relationships between regional atmospheric circulation and peak CEI fire weather conditions (e.g., BUI maxima) through the different fire season phases (i.e., wind, duff, drought, and diurnal periods) during the 1979-2020 period. We will first provide an overview of past fire studies conducted through a synoptic circulation framework. We will then introduce the updated Alaska Blocking Index (ABI), a metric that quantifies the overlying middle tropospheric flow. Subsequently, we will discuss the ABI’s associations, at weekly-to-monthly lead times, to intraseasonal peaks in CEI fire weather conditions. Case studies detailing ABI conditions preceding extreme fire years will also be summarized. We will conclude with a discussion of paths forward and potential applications of the ABI and other regional ocean-atmosphere indices toward Alaska wildland fire prediction at lead times out to the seasonal scale.