Thursday, October 5, 2017

Warm Season Recap: Fire Acreage

This year's fire season produced about 650,000 acres of wildfire in Alaska, which is very close to the median annual acreage since 1990.  Two-thirds of the total acreage burned in July, and this is similar to the past two years, even though 2015 total acreage was far higher.  Over the long term, July is the most active month for fires, but if it's not a very active year then it's not uncommon for June to produce more acreage.  August is only a significant month for fires during very active fire years.

A quick view of the geographical distribution of fire acreage in the northern half of the state is available from the acreage breakdown between the federal fire management zones:

This year 63% of the state's total fire acreage occurred in the Upper Yukon zone, which is the highest percentage on record (1990-present), although of course far higher acreage totals have occurred in previous years.

It's interesting to note that the Upper Yukon fire acreage is easily the most variable of the zones from year to year, while the Galena acreage is the least variable.  It would be interesting to explore how this is related to systematic differences in inter-annual variability of warm season weather conditions from west to east across northern Alaska; presumably the summer weather patterns vary from "very unfavorable" to "very favorable" for fire in the northeast, whereas the northwest is more often somewhere in the middle.


  1. Probably has something mainly to do with historic lightning events and available fuels. Somewhere's there's historic data on intensity and location of strikes and estimated fuel types.

    Probable cause of fires (lightning or human) is noted by the Alaska Fire Service in their situation reports.

    How aggressive the agencies attack to suppress the fires varies by land ownership, land management plans, and proximity to valued property and structures. Lots of variables involved.



      Link to historic lightning strikes in Alaska 1986 -> 2017.


    2. One more recent info on lightning as a driver of boreal forest fires:


    3. Thanks for the suggestions, Gary, and the Nature link. Alaska's historical lightning data are not comparable pre- and post-2012, but it may still be possible to do a spatial comparison across different regions.