The trouble with historical fire comparisons

Can you feel it? That seasonal change is coming — tree leaves are starting to turn color, temperatures are dropping a little. The official day for Autumn Equinox is Sept. 22 this year. Cool, crisp air and clear skies, if we don’t get any more wildfire smoke — fingers crossed!

We’ve been blanketed again this season with much smoke and fine particulate matter. We’ve seen an active wildfire season and smoke has filtered into our region from considerable distances. Early in August, we got hit with the Grass Valley Fire that blew through on our west. It was driven by high wind and fed by drought conditions. Northwest Grand Coulee and west Coulee Dam were evacuated. I’ve been reading a number of different sources this summer that have addressed the trending of western wildfires over the decades. Some are saying it’s the worst ever recorded, while others say it’s not.

There’s much to consider as a review of past historic wildfires are compared to what we are seeing today. How was the gathering of data and reporting done and by whom? There’s also the question of accuracy in the data gathered for each of those fires. I recall when the fire perimeter was walked and measured in “chains.” One chain was 66 feet (20 meters) and 80 chains equals one mile. Today, a combination of satellite and or aircraft over flight imagery and the use of Geographic Information System (GIS) and Global Positioning System (GPS) provide easy-to-determine data of fire size and what actually burned. Remember, it’s all about accuracy — garbage in, garbage out.

On the “Total Wildland Fires and Acres (1926–2017)” webpage, the National Interagency Fire Center (NIFC) in Boise, Idaho, states: “Prior to 1983, sources of these figures are not known, or cannot be confirmed, and were not derived from the current Situation Reporting process. As a result, the figures prior to 1983 should not be compared to later data.”

Randy Eardley, chief of external affairs at the Bureau of Land Management, NIFC, said, “I wouldn’t put any stock in those numbers. To try and compare any of the more modern data to that earlier data is not accurate or appropriate, because we didn’t have a good way to measure [earlier data]. Back then we didn’t have a reliable reporting system; for all I know those came from a variety of different sources that often double-counted figures. When you look at some of those years that add up to 60 or 70 million acres burned, a lot of those acres have to be double counted two or three times. We didn’t have a system to estimate area burned until 1960, but it was really refined in 1983.”

Let’s take a look at the weather results for August: Precipitation was enough to dirty the windshield. I measured 0.05 inches, while the all-time record is 1.76 inches in 2014. The all-time mean is 0.42 inches. Last year, we got zero.

We had three days in a row with highs over the century mark. The high was 106.5˚F on the 9th of the month. The all-time record high is 110˚F back in 1961. Our mean for August was 72.6˚F, while the all-time mean high is 72.0˚F. The low for the past month was 50.2˚F. The all-time mean low is 47˚F and the lowest low recorded for August was 38˚F in 1951.

There will be a full moon, the Harvest Moon, on Sept. 24. Also, maybe you were lucky and saw the “Green Comet,” 21P Giacobini–Zinner, late Monday night in the eastern dark sky.