A perfect firestorm: This wildfire season could be one of South Dakota's worst
Small talk about the weather generally circles around two topics: how nice it is and how unusual it is.
In South Dakota, where multiple seasons can be experienced in a single day, the conversation often ties into a practical theme, whether you're talking to a farmer or a meteorologist: "we could use some rain."
A blizzard in northwestern South Dakota brought much needed moisture to the area late April, and the eastern part of the state benefitted from storms over the weekend.
Still, this summer's fire season outlook does not look optimistic, according to Darren Clabo, state fire meteorologist and research scientist at South Dakota Mines.
"Spoiler alert: We're looking at some pretty high fire potential," Clabo said during a fire weather presentation hosted over Zoom on Tuesday. "I think we're going to have a very active summer, not only in South Dakota, but across the broader western United States."
Clabo says it's difficult to compare fire seasons on a year-to-year basis. He concludes there is an above average potential for wildfire, and asked whether this fire season will be worse compared to previous droughts, he said that is his expectation.
South Dakota is currently experiencing drought across the majority of the state, particularly the west half of the state, but the worst of it can be felt along the Missouri River, with reports of extreme drought extending into the southeastern counties, according to the U.S. Drought Monitor.
The last major drought in the state occurred between 2012 and 2013. The lower half of South Dakota suffered from exceptional drought at its peak in October 2012.
Recent precipitation will, at best, delay the fire season by a few weeks. The state meteorologist says continuous rainfall will be needed to make an actual dent in his projections.
Two years into an ongoing drought, South Dakota has all the elements in place for one of its worst fire seasons yet.
According to National Oceanic and Atmospheric Administration (NOAA) data, nearly every region of the state is experiencing some form of a precipitation deficit, down anywhere from 0 to -6 inches of rainfall and other types of precipitation between April 2021 to April 2022.
Parts of southeast and southcentral South Dakota are reporting much lower numbers than normal, with departure from normal precipitation sitting predominantly in the -6 to -12-inch range during that same time period.
Conversely, the northeast corner of the state is faring better: the last 12 months saw equal and above-average precipitation, depending on the county.
What this means is there is potential for drier fields, making it easier for common culprits in human-caused fires, like cigarette butts and sparks from dragging chains, to ignite.
The second element in this one-two drought punch is the abnormally dry soils throughout South Dakota.
Between mid-April and the start of the year, the southern two-thirds of the state only received roughly 25-35% of precipitation compared to a normal year.
"We're starting off the year worse than last year already," said SDSU Extension State Climatologist Laura Edwards. "Typically, this time of year, we're getting wetter."
Wet soils are vital to mitigating fire potential for a variety of reasons, Edwards says.
A moistened landscape can prevent fires from spreading, but the scant amount of rainfall the state saw during the last two years has failed to penetrate into the ground in some areas.
Supplementing the dry spell, a diminished snowpack – layers of compressed snow that act as a reservoir for soil during the hotter months – left the landscape exposed last winter, drying out South Dakota's plains, Clabo says.
A parched prairie points to an issue greater than what's on the surface, literally. Without soil moisture, underground organic matter – plant and tree roots, for instance – can also dry out and burn if set ablaze.
"We're talking feet of dead, decayed organic material beneath the soil," Clabo adds. "Driving a fire engine through a field to put out a fire is all fine and dandy, but when the soil underneath burns, and you take off after putting out the surface fire, the underground can still smolder [and reignite]."
"Southeast South Dakota has really been under the gun," the meteorologist states, on account of the high precipitation deficits and an anomalously low soil moisture pattern centered on the southeast border with Nebraska.
Clabo followed up his wildfire outlook with a text on May 2, saying precipitation at the start of May benefitted eastern South Dakota, but the southeastern counties are "still only at about 50% of their annual average for this time [of] the year."
This is a primary source of concern for the two climate buffs. Clabo goes as far as calling the dry soils "extraordinarily problematic." According to his climatologist-counterpart Edwards, whose work focuses on long-term weather patterns, soil moisture is a good indicator of how bad a drought and, by extension, a fire season might be.
This summer has two more indicators of a high fire risk: temperatures in South Dakota have risen to a little more than 3 degrees Fahrenheit higher than the century average of 46.1 degrees since 2020.
Meanwhile, annual precipitation also dramatically sank below the 100-year mean from about 38 to 18 inches between 2019 and 2020.
"We're looking at a warmer and a drier-than-average summer across the region, and when we start to see those long-duration periods of hot temperatures combined with short, seven-to-10 day precipitation droughts, we really tilt the scales toward big fire activity," Clabo says.
However, this metric does not necessarily apply statewide.
Typically, eastern South Dakota sees more fires in April than in any other month on average, Clabo explains, because of the seasonal wind gusts and lack of snowfall this time of year.
However, this same region also experiences less wildfires on average compared to the rest of the state thanks to its agriculture community.
Clabo elaborates this is because of higher dew points as a result of farming over the last century. He says planting row crops, like corn and soybeans, dramatically increases the amount of water vapor in the air, leading to higher humidity and precipitation levels and lower actual temperatures.
Clabo also points to La Niña, a phenomenon where a cooling of the Pacific Ocean surface temperatures influences weather in North America, as a potential factor in his projections.
This presents a pattern "eerily similar" to 2012, another major drought year that saw 2,784 wildfires and over 270,000 acres burned in South Dakota alone following a two-year La Niña, as 2022's variant of the weather event starts to wind down.
Wind: The wild card we don't need
The recent gusts are an unusual factor to consider in this wildfire outlook, Clabo says, because it's difficult to account for its actual impact on the weather. Most metrics for analyzing drought only indirectly include wind.
Despite that, Clabo states windy conditions across South Dakota have undeniably had an effect on the weather compared to a year with less wind but similar temperature and precipitation levels.
Winds tend to accelerate the evaporation of moisture, Clabo says, leading to further drying.
Wind is often a chief concern for firefighters trying to contain a fire because, other than providing oxygen necessary for growth, a front can scatter embers dozens of miles away, which can start offshoot spot fires far away from the main ignition.
There is a historical reference to pull from in that regard: the Schroeder Fire, which burned 2,224 acres of land near Rapid City in March 2021, proliferated due to 70-mph wind gusts.
Where the worst of it could be
Based on all this information, western South Dakota, broadly speaking, could see the worst of the wildfires, Clabo said.
Harding, Perkins and Butte county contains quite a bit of tinder, as well as Pine Ridge, Rosebud and Standing Rock Indian Reservations.
The Black Hills are especially primed for wildfires, of which more than half are lightning-induced.
However, both Clabo and Edwards agree most of the potential can be mitigated if South Dakotans can avoid starting them.