Record-setting September precipitation in La Plata County, including last Sunday’s 1.72 inch deluge, has damaged over a dozen local roads, destroyed crops, and damaged local homes.
It is either the wettest or second wettest September on record for the Durango area, depending on which data set is used, said Joe Ramey, meteorologist for the National Oceanic and Atmospheric Administration in Grand Junction, in a phone interview.
By Monday, 4.64 inches of September precipitation had been reported at the Durango-La Plata County Airport, making the precipitation triple of the average for September, according to NOAA.
In one 24-hour period from Sept. 21-22, 1.72 inches of rain fell at the Durango-La Plata County Airport.
Up to 18 La Plata County Emergency Response Personnel and 12 pieces of heavy machinery were operating county-wide on Sunday, according to the La Plata County website. County Road 250 was again cited as the biggest problem area, where several tons of mud and debris have washed across the road.
“They are considered to be debris flows when they carry rocks and boulders in a matrix of mud and water,” said Andy Gleason, a geologist for Trautner Geotech, who worked for the Colorado Geological Survey to map the potential debris flow from the 2002 Missionary Ridge Fire.
This debris flow matrix is capable of moving boulders 20 feet in diameter, and the steep channels that drain the ridge above CR 250 are scraped down to bedrock in these events, Gleason said.
The road has a long history of debris flow events that precedes the Missionary Ridge Fire, said Gleason, citing studies by former FLC students, which found that the area has produced debris flows for at least 3,600 years.
“The debris flow hazard is exacerbated after forest fires,” he said. “But unfortunately the slopes above CR 250 are always prone to debris flow.”
At least two local farms have reported losing the fall harvest to flood damage, said Rachel Landis, the coordinator of the FLC Environmental Center.
FLC student Jandrea Fevold and four friends took a day trip on Sunday to Ouray to soak in the Salt Cave Hot Springs, but they were forced to rent a room there when debris flows closed U.S. Highway 550 in both directions.
“In the three years I’ve been here, I’ve never seen conditions like this, and it was bizarre to see the fall colors with snow on them,” Fevold said.
The recent storms have been well received by the boating community, since the Animas River was running at 1700 cubic feet per second on Tuesday. The mean historical flow for the same date was 477 cfs.
Commercial rafting outfitters in Durango aren’t seeing a big increase in trip bookings from the higher water levels, but the trips are much more fun and add-ons like photos and wetsuit rentals do increase, said Alex Mickel, owner of Mild to Wild Rafting.
Has Durango experienced the “biblical flooding” that dominated national headlines last week? Not exactly, Ramey said.
“It’s a good monsoon season that is setting precipitation records, but it still is not out of the realm of historical extreme Colorado weather,” Ramey said.
To contrast Durango’s present saturation with the Front Range flooding, consider that the National Weather Service reported that Boulder received 8 inches of rain during one 24-hour period and 17 inches of rain over an eight day period.
NOAA officials refer to the Front Range flooding as a 1-in-1000 year event, and on Monday Vice President Joe Biden arrived to tour the impacted region, according to the Associated Press.
The same day authorities in Larimer County confirmed Northern Colorado’s eighth flood related fatality, a 79-year-old woman was swept from her home and found along the Big Thompson River.
Much of the precipitation in Southwest Colorado has fallen as unusually large hailstones, accompanied by lightning.
In La Plata County, golf-ball-sized hailstones were reported during both of last week’s storms, and reports of “hen egg-sized hail” were arriving from other parts of the state, Ramey said.
September and October mark Colorado’s traditional hail season, since the monsoon moisture that freezes in the atmosphere doesn’t always melt into raindrops like it does during the summer, Ramey said.
“To produce one inch diameter hailstones, it takes a real well-organized storm with winds that force an ice ball up and down many times, but it is not all that rare to see this occur during the fall here,” he said.
When asked if the recent monsoon intensity is related to global warming, Ramey quickly cautioned against assigning any specific weather event as a climate change symbol.
Nevertheless, he said that NOAA studies are in agreement about forecasted temperature increases in the southwest, and he thinks that this temperature change is likely to produce more extreme precipitation events.
“From all indications from NOAA scientists, storm intensities will be amplified as heat energy is added to the systems,” he said.
The 2013 draft of the National Climate Change Assessment predicts that temperatures will rise significantly in the southwest U.S., and it is expected that precipitation levels will decline. The report was prepared by the U.S. Global Change Research Team, a federally funded,13 organization program.
The team’s 2009 report found that extreme precipitation events have increased in the southwest region by nine percent since 1958 and significantly more in other parts of the country. The report notes that over the past 55 years the country has received increased amounts of moisture, but the moisture has fallen in fewer rainy days, suggesting more intense storms.