Future changes in Simultaneous Megafires over the United States as projected by NA-CORDEX Simulations

Simultaneous very large wildland fires present a unique challenge to fire management and firefighting resource allocation.

Here we present potential changes in very large wildland fire simultaneity projected by an ensemble of regional climate model simulations produced for the North American Coordinated Regional climate Downscaling Experiment (NA-CORDEX) over multiple United States (U.S.) Geographic Area Coordination Centers (GACCs), the main regions over which wildland firefighting resources are coordinated.  The NA-CORDEX simulations evaluated used the RCP8.5 future scenario, cover the years 1950-2100, and roughly span the range of climate sensitivity seen in the CMIP5 simulations.

To calculate simultaneity, we fit generalized linear models (GLMs) with a negative binomial response to observational data to predict megafire simultaneity based on multiple fire weather indices per GACC.  These indices include: KBDI (Keetch-Byram Drought Index), CFWI (Canadian Fire Weather Index), mFFWI, (modified Fosberg Fire Weather Index), ERC (Energy Release Component), BI (Burning Index), FM100, and FM1000 (100- and 1000-hour Fuel Moisture).  The resulting GLMs for the best index-based predictors were then applied to the NA-CORDEX simulations. 

Future projections of changes in the probability of different levels of simultaneity centered on multiple future timeslices will be presented, along with the uncertainty associated with the choice of simulation.