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It’s been a disorienting start to the fall for western North Carolina.
In September, almost all of our western counties experienced drought, hurting corn crops and sparking wildfires. Now, as if that isn’t enough, Hurricane Helene promises to usher in torrential rain.
READ MORE: WNC Weather: High flood risk, strong winds, heavy rain likely from Helene system
After a dry summer, western North Carolina lost some of its corn crop. Fires, like the one recently contained in the Flint Gap area of the Great Smoky Mountains National Park, sparked and were contained.
“I can only handle this many hazards a week and it seems like these situations are happening more and more,” said Kathie Dello, the director of North Carolina’s state climate office.
Across Appalachia, and particularly in West Virginia, southwestern Virginia, eastern Kentucky, Ohio, Pennsylvania, and east Tennessee, abnormally dry conditions have persisted since June. Communities have reported streams slowed to a trickle, trouble with late-season crops, and even unexpected effects like angry swarms of starving yellowjackets.
As the climate warms, Dello said, we’re in a pattern of drier dries and wetter wets, which could be dangerous. Hot weather causes multiple feedback loops, which are tough to get out of once soils are dry and compacted.
“What I'm thinking about long-term,” Dello said, “are the compounding hazards of okay, now there's a drought and you get a bunch of rain from a tropical system and then you get landslides, or I’m thinking about the compounding hazards between drought and fire.”
Mountain weather systems are complex, Dello said, and we’re not as resilient as we think. Mountain forests are reliant on rainwater, and increasing development in the woods makes us more vulnerable to these compounding hazards, affecting industry, farms, infrastructure, and homes.
Ronald Leeper is a climate scientist at the North Carolina Institute for Climate Studies. He’s been tracking drought data for a long time. For counties that were classified only last week as in “severe drought”, which scientists call D2, this is a fairly unusual turn of events – three categorical changes in a week.
“There's this concept of flash drought – where drought occurs, really really rapidly and I think there has to be a flip side of this where you're improving really really rapidly,” said Leeper, who says the effects of such rapid changes still need more research.
Drought is monitored a number of ways and is classified dependent on the usual conditions. For parts of the southwest, where three months without rain is normal, it takes a lot to classify a drought. For the Blue Ridge Mountains – where there’s a small percentage of a chance of rain most days of the year – it takes only a few dry days. As rainfall deficit continues over time and reduces the rate of flow in mountain streams, it’s considered a meteorological drought.
When plants are stressed, crop yields are significantly reduced. As soils dry, agricultural drought begins. At that point, Leeper says, dry soils begin to actually repel water, which leads to runoff when it rains. Smaller amounts of rain spread over a longer period help the soil absorb the moisture it needs, but a lot of rain over a short period, as is increasingly likely, can just cause more damage.
Nonetheless, Hurricane Helene is expected to alleviate some pressure from drought, Leeper said. However, conditions are expected to be hazardous throughout much of the region. On Wednesday, Gov. Roy Cooper declared a state of emergency and officials warn of abnormally high risks as a flood watch covers most of Western North Carolina through late Friday.
As the climate warms, extreme outcomes like what we’ve seen this week aren’t guaranteed, but they’re much more likely, Leeper added.
Watching for extreme weather, he added, is like “loading the dice in terms of what kind of extreme events you can have.”
