June rain seems like a good thing for Southwest Colorado, especially during a dry and drought-stricken start to the summer. But when storms are as brief and lightning-heavy as the few that have hit Durango so far this month, they have the potential to do more harm than good.
Lightning from several short-lived June downpours have already caused several small wildfires across the region, including the Hermosa Cliff Fire, which burned about 20 acres on the San Juan National Forest earlier this month.
Lightning is the No. 1 cause of wildfires that start in the San Juan National Forest, said spokesperson Lorena Williams.
“We obviously have a significant number of human-caused fires that start on roadways (and) private lands that come onto the San Juan, but in terms of the No. 1 cause of fires starting on the San Juan National Forest, it is lightning,” she said. “The storms like we’ve had the last day or two are the exact situations that cause fires like the Hermosa Cliff Fire.”
According to National Weather Service Meteorologist Kris Sanders, short-lived, early season thunderstorms often bring plenty of lightning and wind – but are less likely to bring impactful amounts of moisture.
Dryer storms often generate gusty winds as a result of rain evaporating in dry air near the surface, which can create strong downdrafts and outflow winds that can reach 60 mph, he said.
“Maybe you’re getting sprinkles or you’re just getting a hundredth (of an inch of moisture) and it’s still going to produce lightning like it normally does, and that’s the problem with the fire starts,” Sanders said.
More beneficial rains that bring deeper moisture generally don’t arrive until monsoon season – in July and August, he said.
There’s a chance of rain in the Durango area this weekend, Sanders said, but nothing is definitive. A windy pattern is also developing in the area, with red flag warnings expected to be issued for the area in the coming days.
Toward the end of June, slightly above-normal precipitation chances are forecast for La Plata County. But even “normal” June rain is dry in Southwest Colorado, Sanders said, meaning that outlook may not mean much.
Some lightning-caused fires in the San Juan National Forest this month have been detected and responded to, Williams said – but recent storms could have started fires that haven’t fully shown themselves yet.
“The Colorado DFPC aircraft – the multi-mission aircraft that’s owned by the state of Colorado – just did a flyover of Southwest Colorado doing infrared detection to try and spot any potential starts from lightning, and they did not spot anything earlier this afternoon (Monday), but that doesn’t mean that there aren’t small lightning fires smoldering out there from the last day or two,” she said. “The potential is high. Our fuel moistures are extremely low. Fire danger is very high or extreme across San Juan National Forest, and we have a high expectation that those storms could have caused some fires that just haven’t shown their head yet.”
A main concern and focus for fire managers during the summer fire season is preventing multiple simultaneous fire starts, Williams said. Part of avoiding multiple starts rests with residents and visitors, she said.
“We can’t control lightning. If lightning strikes and starts a fire, we’re going to respond to it, and there’s nothing we can do. But what we can do is prevent human-caused wildfires,” she said. “Our (focus) already shifts to preventing the ones that we can prevent, so that we can take care of the ones that we can’t, without having multiple fires all at once.”
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