Hsl Nnw 37 Fire

199127,142 acresAlaska

The Hsl Nnw 37 Fire burned 27,142 acres, about 42 square miles, across 2 counties. It began on June 23, 1991.

Watch how it happened

Hsl Nnw 37 Fire · 1991

How it happened

See how severely each place burned, revealed outward from where it started.

About this replay
IgnitionJune 23, 1991Historical replay — order not recorded
Final area27,142 ac
Revealed—
Counties2

How severely it burned

Burn severity inside the final perimeter, classified from Landsat images taken before and after the fire.

Map of burn severity across the Hsl Nnw 37 Fire
Burn severity by class
SeverityShareAcres
Highmost vegetation consumed, soils altered21%5,627
Moderatemixed: many trees killed, some survive47%12,666
Lowsurface fire, most trees survive17%4,727
Unburned to lowislands inside the perimeter, little change10%2,835
Increased greennessvegetation greener after the fire than before0.5%126
Not mappedcloud, shadow or water in the satellite images4.3%1,161

21% of the area inside the perimeter burned at high severity, about 5,627 acres; 67% burned at moderate or high severity.

Monitoring Trends in Burn Severity (U.S. Geological Survey and USDA Forest Service). Classes come from the change in a Landsat burn index (dNBR) between images before and after the fire; acres are each class’s share of the fire’s mapped area.

Where it burned

Acres inside each county, measured from the satellite-mapped perimeter.

Acres burned by county
Yukon-Koyukuk Census AreaAK21,160
Northwest Arctic BoroughAK5,994

Other large fires in Alaska in 1991

Monitoring Trends in Burn Severity (USGS and U.S. Forest Service). Type recorded: Wildfire.