Weather

Fire on the Mountains – North Carolina State Climatic Office


In the midst of our worst wildfire season in five years, two wildfires in the past month have emerged from nests atop Piedmont’s highest mountain peaks.

On 9-14 November, a forest fire burned 40 acres on Mount Sauratown in Stokes County, and an even bigger fire started last Saturday on Pilot Mountain in Surry County. Called the Grindstone Fire because of its source near the Grindstone Trail, it burned more than 500 acres at Pilot Mountain State Park and could eventually cover more than 900 acresaccording to the NC Forestry Department.

These two fires are symptomatic of the recent lack of rain and extended drought, now covers nearly half of North Carolina. However, other local and seasonal environmental factors have also fueled these particular fires in the same part of the state.

Photograph of forest fires on Mount Pilot
Fire burns on Pilot Mountain, with its distinctive peak visible in the background. (Photo: Richard D. Hill)

A dry autumn

Our transition from a humid summer to a drier autumn is more of an abrupt one. At Pilot Mountain, NC . Forest Service automatic weather station recorded 4.13 inches of rain in a single event on September 22-23, after an August with a total of more than 5 inches of rain.

In the more than two months since that last September event, only 1.9 inches of rain had fallen there, and each consecutive day, week, and month seemed drier than the previous one. So far, only 0.49 inches of rain has fallen on Pilot Mountain in November, only 0.07 inches left since November 12.

Although that part of the state remains unclassified in Moderate Drought (D1) on the US Drought Watch, short-term extreme dryness is still sufficient to create a landscape for fire activity. Forest.

Pilot Mountain daily rainfall chart in November 2021
Daily rainfall has been limited in Pilot Mountain this month, with only one day (November 12) visible more than a tenth of an inch. (Land lot from Scouting station)

A Killing Freeze

Temperature also plays an important role. After the first freeze of the season at Pilot Mountain on November 4, the fine ground vegetation – such as roadside grasses, rhododendrons, mountain laurels, and hollies – returned to hibernation and returned to normal. so it’s very flammable in the dry days of the past few weeks.

In contrast, eastern North Carolina saw its first freeze nearly two weeks later on November 16, so dormant vegetation in that area didn’t dry out for as long as it did in northwest Piedmont.

Some fires have even broken out in eastern North Carolina. Last week, a fire burned 140 acres in Columbus County, and multiple fires each covered 20 acres or more in the Sandhills.

Photo of azaleas blooming in the mountains of North Carolina
Blooming rhododendrons are a sight to behold, as in this photo from Mount Jefferson, but in hibernation, it provides ready fuel for wildfires. (Photo: NC State Parks)

Terrain tricks

The uplift of western North Carolina causes some interesting environmental effects that have also helped these fires grow.

On clear nights, heat exchange takes place along the mountain slopes. Cooler air from the upper slopes escapes downhill, while the warm ground below radiates stored energy upwards. That creates features called heat belt on the middle third of the ridge, where this escaping heat is trapped.

In these belts, overnight temperatures remain warmer with lower humidity, which can cause fires like Sauratown Mountain and Pilot Mountain to burn all day.

Whipping Winds

Today is set to be the windiest day of the month, meaning fires can spread quickly. Statewide, gusts of more than 15 mph are likely, with maximum gusts exceeding 20 mph in parts of the mountains and northern Piedmont.

Therefore, the NC Forestry Authority issued statewide burning ban in effect at 5pm last night until further notice. It prohibits the burning of leaves, branches or other plant materials, including campfires.

Along with limiting the start and spread of new fires, a ban on burning will help teams and resources focus on controlling the Grindstone fire as it includes more Pilot mountains.

North Carolina maximum gust forecast map for November 30, 2021
Forecast for maximum gusts from 8 a.m. on November 30 to 8 a.m. on December 1, from NWS Raleigh.

An initial spark

Historically, lightning has only caused about 2% of wildfires in North Carolina. That means the majority caused by human ignition source.

Such was the case with the Mount Sauratown fire, which began with an unburnt campfire. The cause of the Pilot Mountain fire is unknown at this time, but an investigation will be conducted once it is brought under control.

Even by accident, those sparks spread rapidly among dead vegetation and fallen leaves. At some points, this year’s deciduous season starts early due to the dry weather. In others, it happens a little later than usual thanks to warm october.

For now, however, most of the leaves have fallen off the tree and covered the ground, which has added fuel. On Mount Sauratown, the leaves that fall along the perimeter of the fire contain refuel for some re-burns in recent weeks.

A smoke photo on Mount Sauratown
Smoke hung among the trees on Mount Sauratown earlier this month. (Photo: Walt Unks / Winston-Salem Journal)

A fiery autumn

Most of the past years have been flooded with autumn rainfall. In Year 2020a half-dozen remnants of tropical storms soaked the state through mid-November, while fall 2019 began with a rainstorm. Hurricane Dorian and 2018 was marked by record rain from Hurricane Florence.

To find another active fall fire season, we must go back 2016when eastern North Carolina was under water after Hurricane Matthew but the southern mountains were in extreme drought.

Although 2016 saw more large wildfires than this year, most of the wildfires were on federally owned lands, including the 14,000-acre Tellico Fire in Swain County.

Forest fire chart from September to November every year since 2012
Wildfires September through November on public and private lands since 2012, based on data from the NC Forest Service.

Counting only wildfires on public or private land, 2021 comes close to 2016 being the most active wildfire season in the past decade. As of September 1, the NC Forest Service reports 1,210 fires burning 2,693 acres – and growing – across the state..

While the 2016 drought was more severe this time of the season, December of that year also started with the required few inches of rain. In contrast, our forecast shows more dry days in store and December outlook inclined to below-normal rainfall, consistent with La Nina pattern is happening.

That means fire season won’t end with the last day of climate fall, and Smokey the Bear – along with state and local fire and forestry crews – will be busy moving into winter.



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